Co-reporter:Ali Naderi, Andreas Koschella, Thomas Heinze, Kuo-Chih Shih, Mu-Ping Nieh, Annett Pfeifer, Chung-Chueh Chang, Johan Erlandsson
Carbohydrate Polymers 2017 Volume 169(Volume 169) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.carbpol.2017.04.026
•Sulfoethylated nanofibrillated cellulose was produced by an attractive method.•The nanofibrillated cellulose displayed interesting redispersion properties.•The nanofibrillated cellulose displayed high stability in varying pH-conditions.Sulfoethylated nanofibrillated cellulose (NFCSulf) was produced by an industrially relevant process. The properties of the NFCSulf were compared with those of carboxymethylated nanofibrillated cellulose (NFCCarb), which has been identified as an attractive NFC for several industrial applications. The investigations revealed that NFCSulf is characterized by a higher degree of fibrillation and has superior redispersion properties. Furthermore, NFCSulf displays higher stability in varying pH values as compared to NFCCarb. Hence, NFCSulf may be a more attractive alternative than NFCCarb in applications such as rheological modifiers or adsorbing components in personal care products, in which the performance of NFC must remain unaffected in varying ambient conditions.The superior properties of NFCSulf compared to NFCCarb were proposed to be due to the combination of the unique chemical characteristics of the sulfoethylated reagent, and the larger size of the sulfonate group compared to the carboxymethyl group.
Co-reporter:Olga Grigoray, Holger Wondraczek, Annett Pfeifer, Pedro FardimThomas Heinze
ACS Sustainable Chemistry & Engineering 2017 Volume 5(Issue 2) pp:
Publication Date(Web):December 26, 2016
DOI:10.1021/acssuschemeng.6b02539
The paper describes the synthesis of multifunctional cellulose derivatives (MCDs) containing a fluorescent and a cationic moiety and their application in the functionalization of pulp fibers. The cellulose derivatives, namely N-(3-propanoic acid)- and N-(4-butanoic acid)-1,8-naphthalimide esters of cellulose, differed in the degree of substitution (DS) and by the aliphatic chain connecting naphthalimide photoactive groups to the polymer backbone. The derivatives were decorated with a cationic moiety, namely (3-carboxypropyl)trimethylammonium chloride. The fluorescent pulp fibers were prepared by direct self-assembly of the water-soluble fluorescent MCDs on the fibers in water at room temperature. The results indicated that the adsorption was mainly driven by an ion exchange mechanism. UV–vis and fluorescence spectroscopic studies showed that the adsorption yield of the fluorescent MCDs depended on the length of the aliphatic chain of the photoactive groups. Because of the adsorption, the modified pulp fibers gained fluorescence in the visible part of the spectrum. Under black light illumination, the modified fibers fluoresced, which made them visually distinguishable from the reference fibers. Thus, the fluorescent pulp fibers prepared in a simple way can be potentially used as an authenticity indicator in packaging materials.Keywords: Authenticity indicator; Eucalyptus Kraft fibers; Fluorescent fibers; Multifunctional cellulose derivatives; Naphthalimide group; Polyelectrolyte;
Co-reporter:Daniela C. Ferreira, Gustavo S. Bastos, Annett Pfeifer, Thomas Heinze, Omar A. El Seoud
Carbohydrate Polymers 2016 Volume 152() pp:79-86
Publication Date(Web):5 November 2016
DOI:10.1016/j.carbpol.2016.06.075
•Cellulose carboxylates/tosylate (acetate/butanoate/hexanoate) were synthesized.•Determination of degree of substitution DSCarboxy by FTIR and UV–vis was studied.•The IR peak area and frequency (CO and SO) depend linearly on DSCarboxy.•Empirical polarity of ester films depend linearly on DSCarboxy.•These mixed cellulose esters were shaped into homogeneous nanospheres.Cellulose carboxylate/tosylate mixed esters (Cel-Carboxy/Ts) were synthesized with constant degree of tosylation, DSTs = 0.98 and variable degree of acylation, DSCarboxy; acetate, butanoate, and hexanoate. The tosylate (Cel-Ts) was prepared by reacting cellulose with tosyl chloride in presence of trimethylamine. The mixed esters were obtained by reacting Cel-Ts with carboxylic acid anhydride. The dependence of the following on DSCarboxy was investigated: IR data, including νCO, νSO and peak area (CO); empirical polarity of the films, determined by an adsorbed perichromic dye. We employed these parameters to determine DSCarboxy. Relative to ester saponification, these spectroscopic methods are convenient, expedient, and require much less sample. Mixed esters prepared physically from cellulose tosylate and tosylate/acetate behave only qualitatively similar to (Cel-Carboxy/Ts). The mixed esters were dissolved in acetone and regenerated in water as homogeneous microspheres.
Co-reporter:Thomas Heinze;Melanie Siebert;Peter Berlin ;Andreas Koschella
Macromolecular Bioscience 2016 Volume 16( Issue 1) pp:10-42
Publication Date(Web):
DOI:10.1002/mabi.201500184
This feature article summarizes recent developments in the field of so-called aminodeoxy cellulose derivatives (“amino celluloses”) that are applied for functional surface coating of biofunctional materials. After introducing common manufacturing methods for nanostructurized substrates (material surfaces and nanoparticles) biorelevant amino celluloses are described. It could be demonstrated that cellulose is a unique starting material for chemical modification of hydroxyl groups and the adjacent carbon atom. Amino celluloses are proved to be the modifiable polymer of choice for the biofunctionalization of material surfaces. Amino celluloses posses self assembling properties and may form monolayer composites on a variety of substrate materials.
Co-reporter:Kristin Ganske;Cornelia Wieg;Uta-Christina Hipler;Thomas Heinze
Macromolecular Bioscience 2016 Volume 16( Issue 3) pp:451-461
Publication Date(Web):
DOI:10.1002/mabi.201500324
Co-reporter:Thomas Elschner;Claudia Lüdecke;Diana Kalden;Martin Roth;Bettina Löffler;Klaus D. Jt;Thomas Heinze
Macromolecular Bioscience 2016 Volume 16( Issue 4) pp:522-534
Publication Date(Web):
DOI:10.1002/mabi.201500349
Co-reporter:Martin Obst ;Thomas Heinze
Macromolecular Materials and Engineering 2016 Volume 301( Issue 1) pp:65-70
Publication Date(Web):
DOI:10.1002/mame.201500144
Organo-soluble amino cellulose derivatives were synthesized in a one-pot synthesis by simultaneous reaction of tosyl celluloses with ethylenediamine and 4-chlorobenzylamine. The soluble products obtained form nanoparticles in water by nanoprecipitation. As shown by dynamic light scattering (DLS) and scanning electron microscopy (SEM), their hydrodynamic diameter, zeta-potential, and PDI decrease with increasing hydrophobicity. Moreover, the derivative could be labeled with Fluorescein isothiocyanate (FITC) and forms fluorescent nanoparticles with an unexpected low ydrodynamic diameter, useful for the labeling of biomolecules in bioassays.
Co-reporter:Thomas Heinze;Annett Pfeifer;Andreas Koschella;Jens Schaller;Frank Meister
Journal of Applied Polymer Science 2016 Volume 133( Issue 39) pp:
Publication Date(Web):
DOI:10.1002/app.43987
ABSTRACT
Cellulose p-toluenesulfonic acid esters (TosCell) with degree of substitution (DSTos) between 0.8 and 1.4 were converted with ethylene diamine or tris(2-aminoethyl)amine. In contrast to procedures published, the conversion was carried out without any solvent, i.e., the reagent (amines) was used as reaction medium yielding readily soluble products. Moreover, the absence of an additional solvent makes the recycling of both not-consumed amine and precipitant easy. Recycling experiments proofed the possibility of reusing the isolated ethylene diamine. The DS of 6-deoxy-6-(ω-aminoalkyl)amino groups is between 0.71 and 0.93, which is in accordance with the functionalization pattern of tosyl cellulose and the ability of amines to displace primary tosylate moieties only. Attention must be paid to the precipitant used for the workup procedure; 13C NMR measurements revealed a formation of imine structures in case of precipitation with acetone. Precipitation in 2-propanol did not lead to any side product. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43987.
Co-reporter:Peter Schulze;Martin Gericke;Friedrich Scholz;Holger Wondraczek;Peter Miethe;Thomas Heinze
Macromolecular Chemistry and Physics 2016 Volume 217( Issue 16) pp:1823-1833
Publication Date(Web):
DOI:10.1002/macp.201600160
Co-reporter:Konrad Hotzel, Thomas Heinze
Carbohydrate Research 2016 Volume 434() pp:77-82
Publication Date(Web):3 November 2016
DOI:10.1016/j.carres.2016.08.007
•Efficient one-pot synthesis of new dextran derivatives.•Carboxyl- and amine group of β-alanine are converted independently in one-step by iminium chloride.•Dextran N-[(dimethylamino)methylene]-β-alanine ester is formed selectively.•Detailed structure characterization by means of one- and two-dimensional NMR spectroscopy.An efficient one-pot synthesis of new dextran derivatives is described. The functional groups of β-alanine, i.e., the carboxyl- and amine group, are converted independently in one-step by iminium chloride to form products with a single substituent. The dextran N-[(dimethylamino)methylene]-β-alanine ester is formed selectively. The structure of the resulting polymers is unambiguously determined by means of NMR- and FTIR-spectroscopy and elemental analysis.
Co-reporter:Thomas Elschner ;Thomas Heinze
Macromolecular Bioscience 2015 Volume 15( Issue 6) pp:735-746
Publication Date(Web):
DOI:10.1002/mabi.201400521
Cellulose carbonates as a platform compound open new possibilities for the design of advanced materials based on the most important renewable resource cellulose. In the present feature, the chemistry of cellulose carbonates is discussed considering own research results adequately. After a short overview about methods for activation of polysaccharides for a conversion with nucleophilic compounds in particlur with amines, details about various methods for the synthesis of polysaccharide carbonates are discussed. The main issue of the feature is the synthesis and aminolysis of cellulose carbonates with low, intermediate, and high degree of substitution and the evaluation of this chemistry with respect to specific challenges. Functional cellulose carbamates, obtained from cellulose phenyl carbonate by aminolysis, show the potential use of this class of celluloses. Immunoassays and zwitterionic polymers are included as representative examples regarding properties and application of the new cellulose-based products.
Co-reporter:Thomas Elschner, Aleš Doliška, Matej Bračič, Karin Stana-Kleinschek, Thomas Heinze
Carbohydrate Polymers 2015 Volume 116() pp:111-116
Publication Date(Web):13 February 2015
DOI:10.1016/j.carbpol.2014.04.101
Highlights•Novel cellulose derivatives showing nanostructuring.•Film formation of ω-aminoalkylcellulose carbamates was studied by QCM-D and AFM.•Adsorption onto gold surface takes place in the presence of carbonate or phosphate ions.•Structure–property-relationships could be concluded from layer formation.•Film formation is highly dependent on the pH value.The film formation of novel ω-aminoalkylcellulose carbamates on gold surface was studied by means of quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). The influence of the pH value of the buffer solution, the concentration, the degree of polymerization, and the structure (spacer length) of the polymers on the coating was investigated. The layer formation was explained based on the pKa value and the degree of substitution of the ω-aminoalkylcellulose carbamates determined by potentiometric titration. This work provides novel supporting materials that might be applied in field of immobilization of biomolecules.
Co-reporter:Velina Sarbova, Andreas Koschella, Fei Cheng, Stephen M. Kelly, Thomas Heinze
Carbohydrate Polymers 2015 Volume 124() pp:117-123
Publication Date(Web):25 June 2015
DOI:10.1016/j.carbpol.2015.01.080
•A water-soluble cellulose derivative bearing disulfide moieties was prepared.•Sulfuric acid half ester groups induce water solubility.•Structure characterization was carried out by NMR spectroscopy.•Both sulfation of hydroxyl groups and partial oxidation of the disulfide to the stereoisomeric S-oxides were evident.•Cellulose α/β-lipoate sulfate proved to stabilize gold nanoparticles in aqueous dispersion.A versatile method for the synthesis of cellulose α-lipoate with a low degree of substitution (DS) has been developed using N,N-dimethylacetamide (DMA)/LiCl as a solvent and N,N′-carbonyldiimidazole (CDI) as an esterification reagent. The cellulose α-lipoate with DS of α-lipoate groups of 0.26 was converted with sulfur trioxide–pyridine complex in dimethyl sulfoxide (DMSO) as solvent. The sulfation is accompanied by an unexpected partial oxidation of the disulfide moiety leading to the formation of the corresponding stereoisomers of S-oxides. The resulting mixture of water-soluble cellulose α- and β-lipoate sulfate possesses a DS of sulfuric acid half ester groups of 1.78. This cellulose-α/β-lipoate sulfate derivative can be used as an effective stabilizer and solubilizer for the formation of colloidal suspensions of gold nanoparticles formed in situ in aqueous solution.
Co-reporter:Leonore Bretschneider;Andreas Koschella;Thomas Heinze
Polymer Bulletin 2015 Volume 72( Issue 3) pp:473-485
Publication Date(Web):2015 March
DOI:10.1007/s00289-014-1281-4
Cellulose p-toluenesulfonic acid ester was obtained by conversion of cellulose with p-toluenesulfonic acid chloride and triethylamine in N,N-dimethylacetamide/LiCl solution. Further reaction with sodium azide afforded the corresponding 6-deoxy-6-azido cellulose with almost complete displacement of the sulfonate groups. Conversion of 6-deoxy-6-azido cellulose with carboxypropyltrimethylammonium chloride in the presence of N,N′-carbonyldiimidazole yielded 6-deoxy-6-azido cellulose-2,3-O-[4-(N,N,N-trimethylammonium)]butyrate chloride with the degree of substitution of cationic groups up to 0.24. Alternatively, conversion of 6-deoxy-6-azido cellulose with 4-bromobutyltrimethylammonium bromide in the presence of sodium hydroxide in 2-propanol slurry afforded 6-deoxy-6-azido-2,3-O-(4-trimethylammonium)butyl cellulose bromide with a DS of cationic groups up to 0.30. The resulting products are water soluble provided that the content of cationic groups is sufficiently high. Etherification was found to influence the degree of polymerization much more than esterification. Utilization of dimethyl sulfoxide and sodium hydride caused predominant polymer degradation.
Co-reporter:Mengbo Zhou, Tim Liebert, Robert Müller, Andrea Dellith, Christine Gräfe, Joachim H. Clement, and Thomas Heinze
Biomacromolecules 2015 Volume 16(Issue 8) pp:
Publication Date(Web):July 2, 2015
DOI:10.1021/acs.biomac.5b00540
A new approach toward the fabrication of biocompatible composites suitable for remote melting is presented. It is shown that magnetite nanoparticles (MNP) can be embedded into a matrix of biocompatible thermoplastic dextran esters. For that purpose, fatty acid esters of dextran with adjustable melting points in the range of 30–140 °C were synthesized. Esterification of the polysaccharide by activation of the acid as iminium chlorides guaranteed mild reaction conditions leading to high quality products as confirmed by FTIR- and NMR spectroscopy as well as by gel permeation chromatography (GPC). A method for the preparation of magnetically responsive bionanocomposites was developed consisting of combined dissolution/suspension of the dextran ester and hydrophobized MNPs in an organic solvent followed by homogenization with ultrasonication, casting of the solution, drying and melting of the composite for a defined shaping. This process leads to a uniform distribution of MNPs in nanocomposite as revealed by scanning electron microscope. Samples of different geometries were exposed to high frequency alternating magnetic field. It could be shown that defined remote melting of such biocompatible nanocomposites is possible for the first time. This may lead to a new class of magnetic remote control systems, which are suitable for controlled release applications or self-healing materials.
Co-reporter:Torsten Jordan, Susanne Schmidt, Tim Liebert and Thomas Heinze
Green Chemistry 2014 vol. 16(Issue 4) pp:1967-1973
Publication Date(Web):17 Dec 2013
DOI:10.1039/C3GC41818A
Molten imidazole was found to be an efficient, stable and non-derivatising solvent for starch. Clear solutions with up to 20 wt% starch are accessible in molten imidazole without any pretreatment. Solutions with a starch content of 10 wt% generate dynamic viscosity values between 20 Pas (Hylon VII) and 70 Pas (potato starch). In general, Newtonian behavior of the solutions is revealed by rheological studies. Organic liquids and water can be used as co-solvents with up to 50 wt% without precipitation. Such ternary starch solutions exhibit increased viscosity. Dissolution of starch in imidazole causes some polymer degradation but no change in the chemical structure of the macromolecule as detected by means of NMR- and IR spectroscopy.
Co-reporter:S. Schmidt, T. Liebert and T. Heinze
Green Chemistry 2014 vol. 16(Issue 4) pp:1941-1946
Publication Date(Web):02 Dec 2013
DOI:10.1039/C3GC41994K
The tosylation of cellulose in the eco-friendly solvent NaOH–urea in the presence of the nonionic surfactant polyethylene glycol alkyl-(C11–C15) ether (Imbentin) yields well soluble p-toluenesulfonic acid esters of cellulose (tosyl cellulose). The influence of reaction time, temperature, and molar ratio on the degree of substitution (DS) was studied. The products were characterized by means of NMR- and FTIR-spectroscopy, elemental analysis and size exclusion chromatography. Moreover, 6-deoxy-6-azido-, 6-deoxy-6-(ω-aminoethyl)amino-, and 6-deoxy-6-thiosulfate cellulose could be prepared by nucleophilic displacement (SN) of the tosyl groups.
Co-reporter:Marc Kostag;Tim Liebert ;Thomas Heinze
Macromolecular Rapid Communications 2014 Volume 35( Issue 16) pp:1419-1422
Publication Date(Web):
DOI:10.1002/marc.201400211
Co-reporter:Thomas Elschner;Manuela Kötteritzsch ;Thomas Heinze
Macromolecular Bioscience 2014 Volume 14( Issue 2) pp:161-165
Publication Date(Web):
DOI:10.1002/mabi.201300345
Cellulose phenyl tricarbonates could be synthesized by a novel and fast procedure applying 1-butyl-3-methylimidazolium chloride/pyridine as reaction medium. Even cellulose phenyl carbonates with high degree of substitution are accessible at low molar ratio very efficiently. The reagent phenyl chloroformate is inert in the mixture, which is different from the solvent N,N-dimethylacetamide/LiCl that is usually applied. The products were characterized in detail by two-dimensional NMR- and FTIR-spectroscopy, elemental analysis, and size-exclusion chromatography. This class of cellulose derivatives is a very important intermediate for the design of structures based on cellulose by nucleophilc attack on the carbonyl group.
Co-reporter:Thomas Elschner;Friedrich Scholz;Peter Miethe;Thomas Heinze
Macromolecular Bioscience 2014 Volume 14( Issue 11) pp:1539-1546
Publication Date(Web):
DOI:10.1002/mabi.201400179
Abstract
A novel method for antibody immobilization is discussed and applied in a column based flow through immunoassay system (ABICAP). It is shown that porous polyethylene material can be modified with different ω-aminocellulose carbamates yielding an amino group containing biocompatible support for antibody immobilization. Anti-h CRP antibodies can be bound covalently to the surface via various homobifunctional cross-linkers. The antibody modified filters are validated for the CRP determination in a sandwich ABICAP system. In a 10 min test procedure based on colloidal dye particles, a limit of detection of 5 ng CRP mL−1 and coefficients of variation of <9.1% are obtained.
Co-reporter:R. Hampe
Macromolecular Materials and Engineering 2014 Volume 299( Issue 10) pp:1188-1196
Publication Date(Web):
DOI:10.1002/mame.201400012
Starch acetates bearing the ester moiety predominantly at position 2 of the anhydroglucose unit (AGU) could be synthesized by converting starch with acetic anhydride and imidazole in dimethyl sulfoxide (DMSO). Degraded starch (weight average molar mass, < 16 460 g mol−1) is additionally acetylated at position 6 exceeding a total degree of substitution (DS) of 0.5. Increasing the concentration of starch up to 50 wt% leads to higher partial DS at position 6 under comparable reaction conditions. Using molten imidazole as solvent, an initial regioselective 6-O-acylation is achieved. At higher DS values (>0.3), a random distribution of the substituents appears. The substitution pattern can be revealed precisely by means of 13C and 1H NMR spectroscopy after perpropionylation. Hydrolytic stability of a selected 2-O-acetyl starch in aqueous solution is evaluated by time-dependent capillary viscosimetry.
Co-reporter:Katrin Petzold-Welcke, Katrin Schwikal, Stephan Daus, Thomas Heinze
Carbohydrate Polymers 2014 100() pp: 80-88
Publication Date(Web):
DOI:10.1016/j.carbpol.2012.11.052
Co-reporter:Marc Kostag;Tim Liebert;Omar A. El Seoud;Thomas Heinze
Macromolecular Rapid Communications 2013 Volume 34( Issue 19) pp:1580-1584
Publication Date(Web):
DOI:10.1002/marc.201300497
Co-reporter:Holger Wondraczek, Anne Kotiaho, Marja Niemi, Pedro Fardim, Thomas Heinze
Carbohydrate Polymers 2013 Volume 97(Issue 1) pp:45-51
Publication Date(Web):14 August 2013
DOI:10.1016/j.carbpol.2013.04.040
Highlights•Properties of nanoparticles from coumarin-modified dextrans were investigated.•The coumarin moieties were applied as fluorescence probes.•Time-resolved fluorescence studies reveal two domains of different polarity.•The particle surface is highly polar and the polarity of the core varies.•The morphology of the particles can be controlled by light.The photophysical and photochemical characteristics of nano-scaled particles obtained via solvent displacement from coumarin-modified dextrans were studied by means of absorption- and fluorescence-spectroscopy. The environment-dependent fluorescence emission of the pendant 4-methyl-7-alkoxy coumarin groups was exploited as a probe to gain information about the inner structure of the polysaccharide based nanoparticles. Time-resolved fluorescence measurements showed that the particles had two domains of different polarity and it could be confirmed that the core of the nano-assemblies contained water. Moreover, preliminary experiments were carried out demonstrating the possibility to control the morphology of the nanoparticles by the light induced 2π + 2π cycloaddition of the coumarin substituents.
Co-reporter:Ludmila C. Fidale, Thomas Heinze, Omar A. El Seoud
Carbohydrate Polymers 2013 Volume 93(Issue 1) pp:129-134
Publication Date(Web):1 March 2013
DOI:10.1016/j.carbpol.2012.06.061
This overview is concerned with the use of certain dyes (perichromic indicators, hereafter designated as “probes”) in order to determine the properties of cellulose, its solutions and solid derivatives. It is arranged as follows: (i) the properties of cellulose and its derivatives that are relevant to their applications are listed; (ii) a general discussion is presented on how perichromism can be employed in order to gain information on the medium where the probe is present; (iii) the results of perichromism, as applied to cellulose, cellulose solutions, and derivative films are discussed.Highlights► Using perichromic indicators for investigating cellulose and its derivatives. ► Perichromism is a simple and powerful tool to gain information on the medium. ► Provides information on polarity, acidity, basicity, dipolarity/polarizability. ► Perichromic properties correlate well with DS of cellulose derivatives.
Co-reporter:Jana Wotschadlo;Tim Liebert;Joachim H. Clement;Nils Anspach;Stephanie Höppener;Tobias Rudolph;Robert Müller;Felix H. Schacher;Ulrich S. Schubert;Thomas Heinze
Macromolecular Bioscience 2013 Volume 13( Issue 1) pp:93-105
Publication Date(Web):
DOI:10.1002/mabi.201200243
Co-reporter:Holger Wondraczek;Katrin Petzold-Welcke;Pedro Fardim;Thomas Heinze
Cellulose 2013 Volume 20( Issue 2) pp:751-760
Publication Date(Web):2013 April
DOI:10.1007/s10570-013-9874-x
Nano-scaled particles were obtained from two different cellulose acetates, cellulose acetate propionate, and cellulose acetate butyrate using the emulsification solvent evaporation procedure and the low energy methods of solvent displacement (dialysis and controlled precipitation). The relationship between the formulation parameters and the particle properties were evaluated in case of the emulsification-evaporation technique. For the solvent displacement procedures, the influence of the formulation parameters, and the intrinsic polymer properties like the hydrophilic-hydrophobic balance was evaluated. Comparing the methods, it could be shown that large amounts of small and uniform nanoparticles can be obtained by the emulsification solvent evaporation procedure. The solvent displacement techniques turned out to be very easy to use and to yield narrowly distributed particles as well.
Co-reporter:Thomas Heinze, Yunhui Wang, Andreas Koschella, Antonio Sullo, Tim J. Foster
Carbohydrate Polymers 2012 Volume 90(Issue 1) pp:380-386
Publication Date(Web):1 September 2012
DOI:10.1016/j.carbpol.2012.05.054
The 3-mono-O-alkyl cellulose samples bearing two different ether moieties, namely methyl/ethyl, methyl/n-propyl, and ethyl/n-propyl were synthesized applying protecting group technique. The NMR spectra of the peracetylated products revealed the regioselectivity of the alkylation as well as the degree of substitution of both alkyl moieties. The number average degree of polymerization (DPn) monitored by size exclusion chromatography decreases from DPn 117 (Avicel PH-101, starting material) to DPn 34 (sample 4f) due to the multi-step synthesis. It could be demonstrated that the lower critical solution temperature (LCST) is influenced by the degree of substitution of both alkyl groups. For example, LCST values between 33 and 58 °C were measured for aqueous solutions of 3-mono-O-ethyl/n-propyl cellulose. On the contrary, the thermal behavior of a physical mixture of 3-mono-O-ethyl- and 3-mono-O-n-propyl cellulose, e.g., was controlled by the derivative with the lowest LCST.Highlights► Two different ether groups were selectively introduced at position 3 of the repeating unit. ► The ratio of both alkyl substituents was controlled by the ratio of the alkylating agents. ► The structure was characterized by means of NMR- and FT-IR spectroscopy. ► The aqueous solution of the polymers possesses a lower critical solution temperature. ► The lower critical solution temperature is controlled by the ratio of the alkyl groups.
Co-reporter:Martin Gericke, Jens Schaller, Tim Liebert, Pedro Fardim, Frank Meister, Thomas Heinze
Carbohydrate Polymers 2012 Volume 89(Issue 2) pp:526-536
Publication Date(Web):20 June 2012
DOI:10.1016/j.carbpol.2012.03.040
The tosylation of cellulose in ionic liquids (ILs) was studied. Due to the beneficial effect of different co-solvents, the reaction could be performed at 25 °C without the need of heating (in order to reduce viscosity) or cooling (in order to prevent side reactions). The effects of reaction parameters, such as time, molar ratio, and type of base, on the degree of substitution (DS) with tosyl- and chloro-deoxy groups as well as on the molecular weight were evaluated. Products with a DStosyl ≤ 1.14 and DSCl ≤ 0.16 were obtained and characterized by means of NMR- and FT-IR spectroscopy in order to evaluate their purity and distribution of functional groups within the modified anhydroglucose unit (AGU). Tosylation of cellulose in mixtures of IL and a co-solvent was found to result in predominant substitution at the primary hydroxyl group. Size exclusion chromatography (SEC) revealed only a moderate degradation of the polymer backbone at a reaction time of 4–8 h. Finally, the nucleophilic displacement (SN) of tosyl- and chloro-deoxy groups by azide as well as recycling of the ILs was studied.Highlights► Tosyl celluloses can be prepared by homogeneous derivatization in mixtures of ionic liquids and a co-solvent. ► Reaction time, molar ratio, and type of base determine the properties of the products obtained. ► NMR- and FT-IR spectroscopy as well as SEC were used to characterize tosyl celluloses with DStosyl ≤ 1.14 and DSCl ≤ 0.16. ► Tosyl- and chloro-deoxy groups could be substituted completely by azide. ► Recycling of ionic liquids and co-solvents could is possible.
Co-reporter:Melanie Nikolajski;Jana Wotschadlo;Joachim H. Clement;Thomas Heinze
Macromolecular Bioscience 2012 Volume 12( Issue 7) pp:920-925
Publication Date(Web):
DOI:10.1002/mabi.201200040
Co-reporter:Taha Genco;Lidija Fras Zemlji&x10d;;Matej Bra&x10d;i&x10d;;Karin Stana-Kleinschek;Thomas Heinze
Macromolecular Chemistry and Physics 2012 Volume 213( Issue 5) pp:539-548
Publication Date(Web):
DOI:10.1002/macp.201100571
Abstract
The physicochemical behavior with emphasis on the charging behavior of 6-deoxy-6-(2-(bis(2-aminoethyl)aminoethyl-amino) cellulose sulfate (BAECS) with degree of substitution (DS) of 1.31 (sulfate moieties) and 0.71 (amino moieties) and of 6-deoxy-6-(2-aminoethyl) cellulose sulfate (AECS, DSSulf = 1.41, DSDAE = 0.85, DSTosyl ≈0.09) is studied by using several types of titrations. The amounts of protonated amino groups determined by conductometric titration are 4.02 and 2.53 mmol g−1 for BAECS and AECS, respectively. The amino groups are fully deprotonated at pH ≥ 11, whereas the sulfate moieties determined by polyelectrolyte titration are fully dissociated at this pH value. Furthermore, studies on the antimicrobial and antithrombogenetic efficiencies of the samples are carried out.
Co-reporter:Cíntia Salomão Pinto Zarth;Lidija Fras Zemlji&x10d;;Du&x161;ko &x10c;akara;Matej Bra&x10d;i&x10d;;Annett Pfeifer;Karin Stana-Kleinschek;Thomas Heinze
Macromolecular Chemistry and Physics 2012 Volume 213( Issue 16) pp:1669-1676
Publication Date(Web):
DOI:10.1002/macp.201200057
Abstract
The charging behavior of water-soluble cellulose-4-[N-methylamino]butyrate hydrochloride (CMABH) with different degree of substitution (DS) is investigated by polyelectrolyte titration at different pH values. Samples of high DS (0.92) and low DS (0.31) exhibit a decrease in positively charged groups from pH 2 (3.9 and 1.9 mmol g−1) to pH 9 (0.81 and 0.65 mmol g−1) due to the deprotonation of the ammonium groups. The stability of the ester linkage of CMABH is examined as a function of pH value and storage time (up to 28 d). A hydrolysis of the ester moiety is evident after 2 h at pH 8, which is also proved by ATR-FTIR- and Raman spectroscopy.
Co-reporter:Atsushi Nakagawa, Chiyo Ishizu, Velina Sarbova, Andreas Koschella, Toshiyuki Takano, Thomas Heinze, and Hiroshi Kamitakahara
Biomacromolecules 2012 Volume 13(Issue 9) pp:
Publication Date(Web):July 23, 2012
DOI:10.1021/bm300754u
For the first time, 2-O-methyl- (2MC) and 3,6-di-O-methyl-cellulose (36MC) were synthesized via 3-O-allyl- and 3-O-methyl-cellulose, respectively. Position 6 of 3-O-allyl- and 3-O-methyl-cellulose was protected with the 4-methoxytrityl groups. The reaction time and temperature were optimized to achieve a high regioselectivity at C-6 and to prevent the introduction of the 4-methoxytrityl group at C-2 of the polymer. It was found that the substituent at C-3 of 3-O-functionalized celluloses influenced the reactivity of the hydroxyl group at C-6. The structure was characterized by means of 1H and 13C NMR spectroscopy of the acetates of 2MC and 36MC. 2MC and 36MC were soluble in water and did not show thermoreversible gelation.
Co-reporter:Thomas Heinze;Velina Sarbova;Matilde Calado Vieira Nagel
Cellulose 2012 Volume 19( Issue 2) pp:523-531
Publication Date(Web):2012 April
DOI:10.1007/s10570-011-9646-4
Cellulose mixed esters containing alkylphosphonate and carboxylate groups were prepared homogeneously by a new one-pot method using n-propyl phosphonic acid anhydride (T3P®) in LiCl/N-methyl-2-pyrrolidone (NMP). n-Propyl phosphonic acid anhydride acts as both an activating agent for carboxylic acids and phosphonation reagent. Cellulose mixed esters with DSacyl ranging from 1.4 to 1.8, and DSphos up to 0.7 could be prepared. The structure of the cellulose mixed esters was elucidated by FTIR- and NMR spectroscopy, as well as by GPC and solubility tests.
Co-reporter:Atsushi Nakagawa, Frank Steiniger, Walter Richter, Andreas Koschella, Thomas Heinze, and Hiroshi Kamitakahara
Langmuir 2012 Volume 28(Issue 34) pp:12609-12618
Publication Date(Web):August 1, 2012
DOI:10.1021/la3026528
This article provides detailed insight into the thermoresponsive gelation mechanism of industrially produced methylcellulose (MC), highlighting the importance of diblock structure with a hydrophobic sequence of 2,3,6-tri-O-methyl-glucopyranosyl units for this physicochemical property. We show herein, for the first time, that well-defined diblock MC self-assembles thermoresponsively into ribbonlike nanostructures in water. A cryogenic transmission electron microscopy (cryo-TEM) technique was used to detect the ribbonlike nanostructures formed by the diblock copolymers consisting of hydrophilic glucosyl or cellobiosyl and hydrophobic 2,3,6-tri-O-methyl-cellulosyl blocks, methyl β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-celluloside 1 (G-236MC, DPn = 10.7, DS = 2.65), and methyl β-d-glucopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-celluloside 2 (GG-236MC, DPn = 28.2, DS = 2.75). Rheological measurements revealed that the gel strength of a dispersion of GG-236MC (2, 2.0 wt %) in water at 70 °C was 3.0 times stronger than that of commercial MC SM-8000, although the molecular weight of GG-236MC (2) having Mw = 8 × 103 g/mol was 50 times smaller than that of SM-8000 having Mw = 4 × 105 g/mol. Cryo-TEM observation suggested that the hydrogel formation of the diblock copolymers could be attributed to the entanglement of ribbonlike nanostructures self-assembled by the diblock copolymers in water. The cryo-TEM micrograph of GG-236MC (2) at 5 °C showed rectangularly shaped nanostructures having a thickness from 11 to 24 nm, although G-236MC (1) at 20 °C showed no distinct self-assembled nanostructures. The ribbonlike nanostructures of GG-236MC (2) having a length ranging from 91 to 864 nm and a thickness from 8.5 to 27.1 nm were detected above 20 °C. Small-angle X-ray scattering measurements suggested that the ribbonlike nanostructures of GG-236MC (2) consisted of a bilayer structure with a width of ca. 40 nm. It was likely that GG-236MC (2) molecules were oriented perpendicularly to the long axis of the ribbonlike nanostructure. In addition, wide-angle X-ray scattering measurements revealed that GG-236MC (2) in its hydrogel formed the same crystalline regions as 2,3,6-tri-O-methylcellulose. The influence of the DP of diblock MC with a DS of around 2.7 on the gelation behavior will be discussed.
Co-reporter:Tim Liebert;Matilde C. V. Nagel;Torsten Jordan;Andreas Heft;Bernd Grünler;Thomas Heinze
Macromolecular Rapid Communications 2011 Volume 32( Issue 17) pp:1312-1318
Publication Date(Web):
DOI:10.1002/marc.201100283
Co-reporter:Holger Wondraczek, Anne Kotiaho, Pedro Fardim, Thomas Heinze
Carbohydrate Polymers 2011 Volume 83(Issue 3) pp:1048-1061
Publication Date(Web):30 January 2011
DOI:10.1016/j.carbpol.2010.10.014
Light is a non-invasive stimulus or probe, which retains more and more attention in science and technology. In the present review the reader is informed about the important issue of the interactions of polysaccharides and light. Considering some aspects of polysaccharide structure and properties, topics such as absorption and fluorescence of polysaccharides, the structural analysis using light as a probe, and creation of new materials by combining chromophores and polysaccharides are discussed. Attention is also be given to polysaccharide derivatives, where absorption of light induces structural changes, including photocrosslinking and photochromism.
Co-reporter:Andreas Koschella, Matthias Hartlieb, Thomas Heinze
Carbohydrate Polymers 2011 Volume 86(Issue 1) pp:154-161
Publication Date(Web):1 August 2011
DOI:10.1016/j.carbpol.2011.04.031
Cellulose derivatives bearing azide- and alkyne moieties were prepared by conversion of cellulose p-toluenesulphonic acid ester with sodium azide, on one hand, and propargylamine, on the other. The products obtained were carboxymethylated to yield water soluble multifunctional cellulose derivatives. Elemental analysis, FTIR- and NMR spectroscopy were applied to prove the structure of the polymers. SEC of the hydrogel components revealed values of the degree of polymerization (DP) between 43 and 200 that are acceptable values after this multi-step reaction starting from celluloses with DP 600. The copper(I)-catalyzed 1,3-dipolar cycloaddition reaction (Huisgen-reaction) was applied for the cross-linking. Gel formation occurred within 55 and 1600 s after mixing of the aqueous solutions of both components and copper(I) catalyst. The gelation time was found to depend on both the degree of functionalization and the amount of copper(I) catalyst. FTIR spectroscopy revealed incomplete conversion of the reactive sites. The gels contain up to 98.4% water. Freeze-drying led to spongy materials with a porous structure as visualised by SEM.Highlights► Cellulose derivatives as precursors for hydrogels. ► Gelation via azide/alkyne click-reaction. ► Fast gelation in aqueous solution within 55 and 1600 s. ► Freeze-drying leads to gels with porous structure.
Co-reporter:Martin Gericke;Ale&x161; Doli&x161;ka;Jan Stana;Tim Liebert;Thomas Heinze;Karin Stana-Kleinschek
Macromolecular Bioscience 2011 Volume 11( Issue 4) pp:549-556
Publication Date(Web):
DOI:10.1002/mabi.201000419
Co-reporter:Tim Liebert;Marc Kostag;Jana Wotschadlo ;Thomas Heinze
Macromolecular Bioscience 2011 Volume 11( Issue 10) pp:1387-1392
Publication Date(Web):
DOI:10.1002/mabi.201100113
Co-reporter:Stephan Daus;Katrin Petzold-Welcke;Manuela Kötteritzsch;Anja Baumgaertel;Ulrich S. Schubert;Thomas Heinze
Macromolecular Materials and Engineering 2011 Volume 296( Issue 6) pp:551-561
Publication Date(Web):
DOI:10.1002/mame.201000390
Co-reporter:Martin Gericke;Tim Liebert;Omar A. El Seoud;Thomas Heinze
Macromolecular Materials and Engineering 2011 Volume 296( Issue 6) pp:483-493
Publication Date(Web):
DOI:10.1002/mame.201000330
Co-reporter:Marcel Meil;Tim Liebert;Thomas Heinze
Macromolecular Materials and Engineering 2011 Volume 296( Issue 9) pp:802-809
Publication Date(Web):
DOI:10.1002/mame.201000424
Co-reporter:Atsushi Nakagawa;Dominik Fenn;Andreas Koschella;Thomas Heinze;Hiroshi Kamitakahara
Journal of Polymer Science Part B: Polymer Physics 2011 Volume 49( Issue 21) pp:1539-1546
Publication Date(Web):
DOI:10.1002/polb.22343
Abstract
This article describes detailed structure-property relationships of 5 regioselectively methylated celluloses and 10 diblock cellulose derivatives with regioselective functionalization patterns: methyl 2,3,6-tri-O- (1, 236MC), methyl 2,3-di-O- (2, 23MC), methyl 2,6-di-O- (3, 26MC), methyl 3-O- (4, 3MC), methyl 6-O-methyl-cellulosides (5, 6MC), methyl β-D-glucopyranosyl-(14)-2,3,6-tri-O-methyl- (6, G-236MC), methyl β-D-glucopyranosyl-(14)-2,3-di-O-methyl- (7, G-23MC), methyl β-D-glucopyranosyl-(14)-2,6-di-O-methyl- (8, G-26MC), methyl β-D-glucopyranosyl-(14)-3-O-methyl- (9, G-3MC), methyl β-D-glucopyranosyl-(14)-6-O-methyl- (10, G-6MC), methyl β-D-glucopyranosyl-(14)-β-D-glucopyranosyl-(14)-2,3,6-tri-O-methyl- (11, GG-236MC), methyl β-D-glucopyranosyl-(14)-β-D-glucopyranosyl-(14)-2,3-di-O-methyl- (12, GG-23MC), methyl β-D-glucopy-ranosyl-(14)-β-D-glucopyranosyl-(14)-2,6-di-O-methyl- (13, GG-26MC), methyl β-D-glucopyranosyl-(14)-β-D-glucopyranosyl-(14)-3-O-methyl- (14, GG-3MC), and methyl β-D-glucopyranosyl-(14)-β-D-glucopyranosyl-(14)-6-O-methyl-cellulosides (15, GG-6MC). Surface tension, differential scanning calorimetry, fluorescence, and dynamic light scattering measurements of aqueous solutions of compounds 1–15 revealed that there was no relationship between aggregation behaviors and gel formation, gelation occurred only when the hydrophobic environments formed by hydrophobic interactions between the sequences of 2,3,6-tri-O-methyl-glucopyranosyl units upon heating. The diblock structure consisting of cellobiosyl block and approx. ten 2,3,6-tri-O-methyl-glucopyranosyl units was of crucial importance for thermoreversible gelation of methylcellulose. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1539–1546, 2011
Co-reporter:Atsushi Nakagawa;Dominik Fenn;Andreas Koschella;Thomas Heinze;Hiroshi Kamitakahara
Journal of Polymer Science Part A: Polymer Chemistry 2011 Volume 49( Issue 23) pp:4964-4976
Publication Date(Web):
DOI:10.1002/pola.24952
Abstract
This article describes a new synthesis strategy to prepare diblock copolymers as model compounds for industrially produced cellulose ethers exemplified with methylcellulose (MC). To elucidate a key structure for thermoreversible gelation of MC, five regioselectively methylated celluloses 1–5 (236, 23, 26, 3, and 6 MC), five corresponding methyl-β-D-glucopyranosyl-(14)-cellulosides 6–10, and five equiv methyl-β-D-glucopyranosyl-(14)-β-D-glucopyranosyl-(14)-cellulosides 11–15 were synthesized for the first time via combination of the glycosyl trichloroacetimidate method and the acid-catalyzed methanolysis method. The structure of compounds 1–15 was confirmed by means of NMR spectroscopy and MALDI-TOF MS. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Co-reporter:Cíntia Salomão Pinto Zarth;Andreas Koschella;Annett Pfeifer;Susann Dorn
Cellulose 2011 Volume 18( Issue 5) pp:
Publication Date(Web):2011 October
DOI:10.1007/s10570-011-9557-4
The homogeneous conversion of cellulose dissolved in N-methyl-2-pyrrolidone/LiCl and 1-N-butyl-3-methylimidazolium chloride with N-methyl-2-pyrrolidone, ε-caprolactam, N-methyl-ε-caprolactam, and N-methyl-2-piperidone in the presence of p-toluenesulphonic acid chloride was studied. Depending on the reaction conditions, novel cellulose esters with degree of substitution (DS) values ranging from 0.12 to 1.17 could be prepared. The structure of the amino group containing cellulose esters was elucidated by elemental analysis, FTIR- and NMR spectroscopy. NMR spectroscopy revealed an almost complete esterification of position 6 of the anhydroglucose unit at DS of 1. The conversion can be conducted between room temperature and 40 °C, while side-reactions became predominant at 60 °C. Starting with DS of 0.24, the samples were soluble both in water and dimethyl sulphoxide. The derivatives described are capable of forming polyelectrolyte complexes. The samples were stable at room temperature in aqueous solution at pH 2 and 7. Lower viscosities were found for samples with higher DS in aqueous solution at comparable molar mass.
Co-reporter:Haisong Qi;Quanling Yang;Lina Zhang;Tim Liebert;Thomas Heinze
Cellulose 2011 Volume 18( Issue 2) pp:237-245
Publication Date(Web):2011 April
DOI:10.1007/s10570-010-9477-8
A new dissolution method, a two-step process, for cellulose in NaOH/urea aqueous system was investigated with 13C NMR, wide X-ray diffraction (WXRD), and solubility test. The two steps were as follows: (1) formation and swelling of a cellulose–NaOH complex and (2) dissolution of the cellulose–NaOH complex in aqueous urea solution. The dissolution mechanism could be described as strong interaction between cellulose and NaOH occurring in the aqueous system to disrupt the chain packing of original cellulose through the formation of new hydrogen bonds between cellulose and NaOH hydrates, and surrounding the cellulose–NaOH complex with urea hydrates to reduce the aggregation of the cellulose molecules. This leads to the improvement in solubility of the polymer and stability of the cellulose solutions. By using this two-step process, cellulose can be dissolved at 0–5 °C in contrast to the known process that requires −12 °C. Regenerated cellulose (RC) films with good mechanical properties and excellent optical transmittance were prepared successfully from the cellulose solution.
Co-reporter:Marcel Meiland;Tim Liebert;Anja Baumgaertel;Ulrich S. Schubert
Cellulose 2011 Volume 18( Issue 6) pp:1585-1598
Publication Date(Web):2011 December
DOI:10.1007/s10570-011-9581-4
Non-reducing cellulose mimics, termed alkyl β-d-cellulosides, were successfully prepared by two efficient multi-step syntheses starting from commercially available microcrystalline cellulose or cellulose triacetate. Introduction of the alkoxy moiety and degradation of the cellulose backbone was carried out in the presence of a Lewis acid, on one hand. On the other hand, cellulose hydrolysis mediated by mineral acids was combined with β-glycosidation performed in the presence of silver salts. The samples obtained possess a number-average degree of polymerization from 5 to 25, determined by size-exclusion chromatography, elemental analyses, NMR spectroscopy, and MALDI-TOF mass spectrometry. Samples in multi-gram quantities were available. Selective formation of a β-glycosidic bond between the C-1 atom of the reducing end group and alkoxy moieties was confirmed by a combination of 2D NMR spectroscopic and MALDI-TOF MS techniques. Due to the blocking of the aldehyde function, the cellulosides described are very useful mimics for the investigation of polysaccharide interactions with other complex molecules such as proteins or to determine polymer properties in solution or in solid state.
Co-reporter:Dr. Thomas Heinze;Dipl.-Chem. Melanie Nikolajski;Dr. Stephan Daus;MSc. Tabot M. D. Besong;Dipl.-Chem. Nico Michaelis;Dr. Peter Berlin;Dr. Gordon A. Morris;Dr. Arthur J. Rowe;Dr. Stephen E. Harding
Angewandte Chemie 2011 Volume 123( Issue 37) pp:8761-8763
Publication Date(Web):
DOI:10.1002/ange.201103026
Co-reporter:Tim Liebert, Jana Wotschadlo, Peggy Laudeley, and Thomas Heinze
Biomacromolecules 2011 Volume 12(Issue 8) pp:
Publication Date(Web):July 8, 2011
DOI:10.1021/bm200841b
The conversion of dextran with in situ synthesized iminium chlorides of long chain carboxylic acids was used to obtain pure and defined melting dextran esters in an efficient one-pot synthesis. The melting point of these esters can be tailored by the degree of substitutions (DS), the molecular weight of the starting polymer, and the chain length of the ester moiety. The dextran esters give homogeneous and completely transparent melts, which form stable films on a broad variety of materials. Even complex geometries, such as implants, can be evenly coated by multiple melting steps. The films do not display any inhomogeneity and have a very low surface roughness. Therefore, no unspecific protein binding is observed. Moreover, the dextran esters are biocompatible as demonstrated for the interaction with three types of cells namely human brain microvascular endothelial cell, primary human fibroblasts, and mouse myoblast cells.
Co-reporter:Thomas Heinze;Annett Pfeifer;Velina Sarbova;Andreas Koschella
Polymer Bulletin 2011 Volume 66( Issue 9) pp:1219-1229
Publication Date(Web):2011 May
DOI:10.1007/s00289-010-0345-3
The synthesis of 3-O-propyl cellulose with degree of substitution (DS) ranging from 0.19 to 1.02 was carried out via 2,6-di-O-thexyldimethylsilyl cellulose. The products were characterized by means of one- and two-dimensional NMR spectroscopy after peracetylation. The dissolution behavior of 3-mono-O-propyl cellulose in water was studied and compared with propyl cellulose derivatives having different degree of substitution and distribution of functional groups. Depending on the DS, exceptionally low flocculation temperatures between 15 and 23 °C were found for 3-O-propyl celluloses.
Co-reporter:Stephan Daus ;Thomas Heinze
Macromolecular Bioscience 2010 Volume 10( Issue 2) pp:211-220
Publication Date(Web):
DOI:10.1002/mabi.200900201
Co-reporter:Holger Wondraczek, Annett Pfeifer, Thomas Heinze
European Polymer Journal 2010 Volume 46(Issue 8) pp:1688-1695
Publication Date(Web):August 2010
DOI:10.1016/j.eurpolymj.2010.06.005
Photoactive derivatives of dextran and pullulan with high degree of substitution were prepared by an efficient and mild esterification of the biopolymers with [(4-methyl-2-oxo-2H-chromen-7-yl)oxy] acetic acid via in situ activation of the carboxylic acid with N,N′- carbonyldiimidazole. Subsequently, sulfation was carried out with the gentle and easily manageable SO3/DMF complex as reagent. Thus, water soluble polyelectrolytes decorated with high amounts of photochemically active moieties were obtained. The structures of the novel polysaccharide esters and the polyelectrolytes were evaluated by means of NMR and IR spectroscopy. Moreover, the photochemistry of both the carboxylic acid esters and their sulfated derivatives was studied by means of UV–Vis spectroscopy in the dissolved state. The changes observed may be used to control the properties and are thus of interest in the design of smart materials.
Co-reporter:Matilde C.V. Nagel, Andreas Koschella, Kristin Voiges, Petra Mischnick, Thomas Heinze
European Polymer Journal 2010 Volume 46(Issue 8) pp:1726-1735
Publication Date(Web):August 2010
DOI:10.1016/j.eurpolymj.2010.05.009
Spruce sulphite cellulose (number average degree of polymerization 620) dissolved in an aqueous solution of 8% (w/w) LiOH*H2O and 12% (w/w) urea was methylated with dimethyl sulphate (DMS). By varying the reaction temperature between 22 and 50 °C, the molar ratio between 9 and 15 mol DMS per mol anhydroglucose unit, and the reaction time from 4 to 24 h, methyl cellulose (MC) with degree of substitution (DS) values in the range of 1.07 and 1.59 was prepared. The chemical structure of MC was analysed by FTIR and 1H NMR spectroscopy. The turbidity (given in nephelometric turbidity units, NTU) of the aqueous solution of MC reached an optimum of 10 NTU for a product obtained with 12 mol DMS/mol AGU at 50 °C. GPC measurements revealed polymer degradation to a certain extent. The intrinsic viscosity and the Huggins constant k of the MC samples increased with increasing DS value. The MC samples possess k values higher than 0.8, indicating association of the polymer chain. The zero-shear viscosity decreased with increase of both temperature and the amount of methylation agent due to the depolymerization. During the heating/cooling cycle (20–90 °C) of the aqueous solutions of MC, it was observed that samples synthesized at 22 °C with DS values lower than 1.3 did not undergo phase separation in aqueous solution. Phase separation hysteresis with a precipitation temperature up to 80 °C was obtained for aqueous solutions of MC with DS values between 1.07 and 1.66 synthesized at higher temperatures. The functionalization pattern determined by GLC of the corresponding partially methylated glucitol acetates is close to randomness and comparable with those of commercial MC samples.Methyl cellulose (MC) of different degree of substitution was prepared by conversion of cellulose dissolved in aqueous solution containing urea and lithium hydroxide. GLC analyses as well as enzymatic degradation experiments revealed a nearly random functionalization pattern that is comparable with those of commercially available MC. The samples are water soluble and possess a characteristic thermal flocculation behaviour.
Co-reporter:Andreas Koschella, Martin Richter, Thomas Heinze
Carbohydrate Research 2010 Volume 345(Issue 8) pp:1028-1033
Publication Date(Web):27 May 2010
DOI:10.1016/j.carres.2010.03.007
Novel polyelectrolytes were prepared by conversion of 6-azido-6-deoxycellulose with acetylenedicarboxylic acid dimethyl ester and subsequent saponification. Up to 62% of the azide moieties were converted. The reaction was completed within 48 h using 2 moles of acetylenedicarboxylic acid dimethyl ester per mole of modified anhydroglucose unit. FTIR and NMR spectroscopy were applied to elucidate the molecular structure of the polymers. The polymer degradation was acceptable during this two-step reaction. The resulting biopolymer derivatives were water soluble and reduced the surface tension on water significantly. Moreover, they form ionotropic gels with multivalent metal ions.
Co-reporter:Susann Dorn;Annett Pfeifer;Kerstin Schlufter;Thomas Heinze
Polymer Bulletin 2010 Volume 64( Issue 9) pp:845-854
Publication Date(Web):2010 May
DOI:10.1007/s00289-009-0172-6
Water-soluble, non-ionic cellulose esters with a degree of substitution in the range from 0.11 to 3.0 were synthesized homogeneously using ionic liquids (1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, and 1-allyl-3-methylimidazolium chloride) as reaction medium. Highly substituted 3,6,9-trioxadecanoic acid esters and 3,6-dioxaheptanoic acid esters of cellulose were obtained via the activation of the carboxylic acids with N,N’-carbonyldiimidazole. The products were characterized by the means of FTIR-, 1H- and 13C NMR spectroscopy.
Co-reporter:Katrin Petzold-Welcke;Manuela Kötteritzsch;Dominik Fenn;Andreas Koschella;Thomas Heinze
Macromolecular Symposia 2010 Volume 294( Issue 2) pp:133-140
Publication Date(Web):
DOI:10.1002/masy.201000003
Abstract
The synthesis of hydroxyethyl celluloses with regioselective functionalization in position 2 and 3 starting from triphenylmethyl (trityl) cellulose is described. The effects of reaction conditions upon both the degree of substitution and the distribution of the hydroxyethyl moieties were investigated in detail. The interest was not only focused on regioselective functionalization within the anhydroglucose unit but also on the formation of oxyethylene side chains. To avoid the formation of oxyethylene side chains, 2-(2-bromoethoxy)tetrahydropyran was used as etherifying agent in comparison with 2-bromoethanol. By acidic hydrolysis, both protecting groups – trityl at 6 position and tetrahydropyran at the hydroxyethyl substituent – can be simultaneously cleaved off. The hydroxyethyl celluloses were characterized by one- and two-dimensional NMR spectroscopy in order to determine the substitution pattern.
Co-reporter:Haisong Qi;Tim Liebert;Frank Meister;Lina Zhang;Thomas Heinze
Macromolecular Symposia 2010 Volume 294( Issue 2) pp:125-132
Publication Date(Web):
DOI:10.1002/masy.200900166
Abstract
In this work, the carboxymethylation of cellulose in a new alkaline cellulose solvent, LiOH/urea aqueous solution, was investigated. Carboxymethyl cellulose (CMC) samples were characterized with FT-IR, NMR, HPLC, and viscosity measurements. Water-soluble CMC with DS = 0.36∼0.65 was prepared, from both Avicel cellulose and cotton linters in the LiOH/urea system. The total DS of CMC could be controlled by varying the molar ratio of reagents and the reaction temperature. The results from structure analysis by HPLC after complete depolymerization showed that the mole fractions of the different carboxymethylated repeating units as well as those of unmodified glucose follow a simple statistic pattern. A distribution of the carboxymethyl groups of the AGU was determined to be in the order O-6 > O-2 > O-3 position at the level.
Co-reporter:Kerstin Schlufter;Thomas Heinze
Macromolecular Symposia 2010 Volume 294( Issue 2) pp:117-124
Publication Date(Web):
DOI:10.1002/masy.200900054
Abstract
The carboxymethylation of bacterial cellulose (BC) was studied under typical heterogeneous reaction conditions. It was found that the BC possesses a significantly lower reactivity compared to wood cellulose converted under comparable conditions. Moreover, water-solubility of carboxymethyl cellulose (CMC) obtained from BC appears at rather high degree of substitution of about 1.5 although a nearly statistical functionalization pattern was analyzed by HPLC. Obviously, the nano-structure of BC is important for the reactivity and the properties of the synthesized CMC like water-solubility.
Co-reporter:Esther Rohleder ;Thomas Heinze
Macromolecular Symposia 2010 Volume 294( Issue 2) pp:107-116
Publication Date(Web):
DOI:10.1002/masy.200900034
Abstract
Cellulose was benzylated starting from the dissolved polymer in dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride trihydrate (TBAF) and heterogeneously in aqueous NaOH as reaction media. Differences in the distribution of benzyl moieties within the anhydroglucose unit in dependence on the synthesis pathway couldn't be found. However, as revealed by means of 1H-NMR spectroscopy, significant differences in the distribution of substituents along the cellulose chains occurred. Conventionally synthesized samples (in aqueous NaOH), even in the presence of a phase transfer catalyst, possess a block-wise distribution of substituents, while a dissolution of cellulose in DMSO/TBAF prior to the reaction gives products that are uniformly substituted along the cellulose chains.
Co-reporter:Marc Kostag;Sarah Köhler;Tim Liebert ;Thomas Heinze
Macromolecular Symposia 2010 Volume 294( Issue 2) pp:96-106
Publication Date(Web):
DOI:10.1002/masy.200900095
Abstract
Silyl ethers of cellulose are promising derivatives of the biopolymer because they exhibit thermoplastic behavior at higher functionalization, may be applied as intermediate in subsequent reactions and have a high tendency to form defined supramolecular structures. Trimethylsilylation can be carried out by applying ionic liquids (ILs) such as 1-ethyl-3-methylimidazolium acetate (EMIMAc) as reaction medium. Pure trimethylsilyl cellulose (TMSC) can be efficiently synthesized with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) yielding products with degrees of substitution (DS) up to 2.89. During the synthesis of highly functionalized derivatives, precipitation of the TMSC occurred, which simplifies the recycling of the IL. The tendency of TMSC toward the formation of supermolecular structures was exploited for the formation of pure cellulose nanospheres by a simple dialysis process. FTIR spectroscopy confirmed the complete removal of the TMS functions during this process. Scanning electron microscopy, dynamic light scattering, atomic force microscopy, and particle size distribution analysis showed that cellulose particles with a size of 100 to 200 nm are accessible in this simple manner.
Co-reporter:Stephan Daus;Thomas Elschner;Thomas Heinze
Cellulose 2010 Volume 17( Issue 4) pp:825-833
Publication Date(Web):2010 August
DOI:10.1007/s10570-010-9421-y
Low molecular weight xylan was modified at the reducing end with mono and bifunctional amines. Characterization by means of elemental analysis, nmr spectroscopy and mass spectrometry proved the success of the highly selective reaction. Modified xylan containing amino groups at the reducing end are capable to react with unmodified xylan and cellodextrins. The structure of the products obtained was proved by NMR spectroscopy. Size exclusion chromatography and mass spectrometry verified the increased molar mass of the head-head linked polysaccharides.
Co-reporter:Matilde C. V. Nagel;Thomas Heinze
Polymer Bulletin 2010 Volume 65( Issue 9) pp:873-881
Publication Date(Web):2010 December
DOI:10.1007/s00289-010-0250-9
For the first time, the acylation of cellulose was realized by activation of carboxylic acid with 1H-benzotriazole. The reaction could be carried out under mild conditions. The acyl-1H-benzotriazole reacts with cellulose leading to cellulose acetate, butyrate, caproate, benzoate, myristate, and stearate with DS values between 1.07 and 1.89. The reaction proceeds completely homogeneously in dimethyl sulfoxide (DMSO)/TBAF × 3H2O (tetrabutylammonium fluoride trihydrate) using acyl-1H-benzotriazole as acylation agent. The cellulose esters were characterized by means of 1H NMR, GPC measurements, and solubility tests.
Co-reporter:Martin Gericke ; Tim Liebert ;Thomas Heinze
Journal of the American Chemical Society 2009 Volume 131(Issue 37) pp:13220-13221
Publication Date(Web):September 1, 2009
DOI:10.1021/ja905003r
For the first time, polyelectrolyte complex (PEC) capsules were prepared from a water insoluble polyanion, namely cellulose sulfates (CSs) with a degree of substitution (DS) below 0.2 in ionic liquids (IL). Capsules prepared via interaction with the polycation poly(dimethyldiallyammonium chloride) were free of residual IL and possessed an outer shell and a hollow inner core that made them ideal containers for enzyme mediated reactions. Due to the reestablished hydrogen bond system of the low substituted CS, the capsules showed increased stability, compared to the products obtained by application of the common aqueous preparation. Encapsulation of glucose oxidase demonstrated that the steps of CS preparation, PEC capsule formation, and encapsulation could be combined in a single pot, with the elimination of time and cost consuming isolation and purification steps.
Co-reporter:Stephanie Hornig, Thomas Heinze, C. Remzi Becer and Ulrich S. Schubert
Journal of Materials Chemistry A 2009 vol. 19(Issue 23) pp:3838-3840
Publication Date(Web):01 May 2009
DOI:10.1039/B906556N
Nanoprecipitation is applied for the first time as a general concept for manufacturing nanoparticles of versatile hydrophobic polymer classes. As a result, polymer molecules self-assemble into nanospheres or irregularly shaped nanoparticles during the transition from the dissolved state to the solid state while using different solvents and methods for the conversion.
Co-reporter:Shazia Saghir, Mohammad Saeed Iqbal, Andreas Koschella, Thomas Heinze
Carbohydrate Polymers 2009 Volume 77(Issue 1) pp:125-130
Publication Date(Web):22 May 2009
DOI:10.1016/j.carbpol.2008.12.009
The ethylation of arabinoxylan, isolated from Ispaghula seed husk by alkali extraction, was carried out heterogeneously with ethyl iodide in the presence of aqueous sodium hydroxide (25%). The reaction parameters were varied in terms of molar ratio anhydrosugar unit:reagent, slurry medium, and temperature. In order to determine the total degree of substitution of ethyl groups (DSEt), 1H NMR spectroscopic investigations of ethyl arabinoxylans (EAX) after peracetylation with acetyl chloride in N,N-dimethyl formamide were carried out. Structural elucidation of the peracetylated EAX was conducted by means of 1H, 1H COSY- and HSQC-DEPT NMR experiments. DS values for EAX as high as 0.61 were achieved. Samples were soluble in dimethyl sulfoxide at 80 °C. The intrinsic viscosity [η] of EAX samples depends on reaction conditions applied. The highest [η] obtained was 518 mL/g for a sample synthesized at 40 °C in methanol as slurry medium using a molar ratio arabinoxylan:ethyl iodide of 1:18.
Co-reporter:Stephanie Hornig, Heike Bunjes, Thomas Heinze
Journal of Colloid and Interface Science 2009 Volume 338(Issue 1) pp:56-62
Publication Date(Web):1 October 2009
DOI:10.1016/j.jcis.2009.05.025
The presented concept combines the widely-established use of macromolecular prodrugs with nanoparticulate drug delivery devices. For this purpose, the water-soluble biopolymer dextran was functionalized with poorly water-soluble drugs (ibuprofen, naproxen) via in situ activation of the carboxylic groups with N, N′-carbonyldiimidazole (CDI). The resulting hydrophobic derivatives self-assemble into nanoparticles with high loading efficiency during nanoprecipitation. The degree of substitution (DS) and the preparation technique strongly influence the size and the size distribution of the resulting nanoparticles. The particle suspensions remained stable over months in a pH value range between 4 and 11. Derivatives with high DS values are more stable against hydrolysis and after the addition of electrolytes than lowly substituted ones. Therefore, a defined tuning of the DS value may allow the adjustment of the pH-dependent hydrolysis rate and, hence, the release of the drugs.Dextran–drug (ibuprofen, naproxen) conjugates were prepared, characterized and formulated into nanoparticles with high loading efficiency applying nanoprecipitation.
Co-reporter:Martin Gericke;Tim Liebert ;Thomas Heinze
Macromolecular Bioscience 2009 Volume 9( Issue 4) pp:343-353
Publication Date(Web):
DOI:10.1002/mabi.200800329
Co-reporter:Martin Gericke;Tim Liebert ;Thomas Heinze
Macromolecular Bioscience 2009 Volume 9( Issue 4) pp:
Publication Date(Web):
DOI:10.1002/mabi.200990005
Co-reporter:Sarah Köhler;Tim Liebert ;Thomas Heinze
Macromolecular Bioscience 2009 Volume 9( Issue 9) pp:836-841
Publication Date(Web):
DOI:10.1002/mabi.200900156
Co-reporter:Matthias Pohl, Gordon A. Morris, Steve E. Harding, Thomas Heinze
European Polymer Journal 2009 Volume 45(Issue 4) pp:1098-1110
Publication Date(Web):April 2009
DOI:10.1016/j.eurpolymj.2009.01.009
Water-soluble deoxy-azido cellulose derivatives were synthesized by heterogeneous carboxymethylation, applying 2-propanol/aqueous NaOH as slurry medium. The novel, carboxymethyl deoxy-azido cellulose provides a convenient starting material for the selective dendronization of cellulose via the copper-catalyzed Huisgen reaction yielding water-soluble carboxymethyl 6-deoxy-(1-N-[1,2,3-triazolo]-4-polyamidoamine) cellulose derivatives of first (degree of substitution, DS 0.51), second (DS 0.44) and third generation (DS 0.39). The novel biopolymer derivatives were characterized by FT-IR and NMR spectroscopy, intrinsic viscosity, sedimentation coefficient and weight average molar mass. Solution conformation and flexibility were estimated qualitatively using conformation zoning and quantitatively (persistence length) using the combined global method. Sedimentation conformation zoning showed a semi-flexible coil conformation and the global method applied to each carboxymethyl deoxy-azido cellulose and carboxymethyl 6-deoxy-(1-N-[1,2,3-triazolo]-4-polyamidoamine) cellulose derivative yielded persistence length all within the range of 2.8–4.0 nm with no evidence of any change in flexibility with dendronization.
Co-reporter:Dominik Fenn;Thomas Heinze
Cellulose 2009 Volume 16( Issue 5) pp:853-861
Publication Date(Web):2009 October
DOI:10.1007/s10570-009-9297-x
The synthesis of 3-mono-O-hydroxyethyl cellulose using orthogonal protecting groups was realized. The reaction of 2,6-di-O-thexyldimethylsilyl cellulose with 2-(2-bromoethoxy)tetrahydropyran leads to a completely functionalized cellulose derivative. The complete removal of the protecting groups was possible by split off of the TDMS functions with tetrabutylammonium fluoride trihydrate and subsequently the tetrahydropyran moieties with hydrochloric acid. The structure of 3-mono-O-hydroxyethyl cellulose was confirmed by applying one and two-dimensional NMR spectroscopy. The novel polymer is soluble in water and does not show thermoreversible gelation.
Co-reporter:Stephanie Hornig, Tim Liebert, Alan R. Esker, Sarah L. Stoll, Julie Mertzman, Wolfgang G. Glasser and Thomas Heinze
Langmuir 2009 Volume 25(Issue 9) pp:4845-4847
Publication Date(Web):April 6, 2009
DOI:10.1021/la900454g
The self-assembly of thiophene-containing dextran and cyclodextrin derivatives on gold surfaces was investigated. Morphological studies (AFM) and the elemental characterization (XPS) of the surfaces show that the carbohydrate derivatives form either aggregates or uniform films depending on the structure and the solvent used. The real coverage of the surface, and hence the amount of unmodified free gold, was examined by a “titration” of the surface with a carboxyl-terminated SAM (11-mercaptoundecanoic acid, MUA) and with Mn-12, a manganese oxocluster. Each carboxyl group reacts with one acetate ligand of the manganese cluster, with each Mn-12 cluster capable of binding multiple MUAs, leading to defined manganese-functionalized surfaces. The weight percentage of manganese and consequently the coverage area of the carboxyl-terminated SAM is examined by XPS.
Co-reporter:Michael Schöbitz;Frank Meister;Thomas Heinze
Macromolecular Symposia 2009 Volume 280( Issue 1) pp:102-111
Publication Date(Web):
DOI:10.1002/masy.200950612
Abstract
Summary: Ionic Liquids (IL) were applied as solvent and reaction medium in the field of homogeneous cellulose chemistry. Whereas investigations on tosylation and nucleophilic displacement reactions lead to unexpected products the application of the Huisgen reaction was successful. The standard conditions for tosylation of cellulose using the IL 1-ethyl-3-methylimidazolium acetate (EMImAc) as solvent lead exclusively to cellulose acetate, due to activation of the acetate ion of the IL by forming a mixed anhydride with p-toluenesulfonyl chloride. Further investigations showed that the anions of EMImAc and 1-ethyl-3-methylimidazolium chloride (EMImCl) are able to act as nucleophiles, thus substituting tosyl groups of tosylcellulose and forming unexpected products. Using EMImAc as solvent first to third generation propargyl-polyamidoamine (PAMAM) dendrons were attached to 6-azido-6-deoxy cellulose (degree of substitution, DS 0.75) utilising the copper catalysed Huisgen reaction leading to novel dendronized cellulose derivatives with DS values of up to 0.60. Detailed structure characterisation of the products, including elemental analysis, FTIR and NMR spectroscopy, indicates that the synthesis approach leads to products without impurities or remaining IL.
Co-reporter:Xueqiong Yin;Andreas Koschella;Thomas Heinze
Macromolecular Symposia 2009 Volume 280( Issue 1) pp:95-101
Publication Date(Web):
DOI:10.1002/masy.200950611
Abstract
Summary: 3-Mono-O-(2-methoxyethyl) cellulose (MEC) was selectively oxidized with 2,2,6,6-tetramethyl-1-piperidinyloxy radical (TEMPO)/NaBr/ NaOCl. According to 1D and 2D NMR measurements, the primary hydroxyl group was completely oxidized without affecting the secondary one at position 2. Size-exclusion chromatography revealed high tendency of 3-mono-O-(2-methoxyethyl)-6-carboxyl cellulose (MECO) to aggregate. Viscosity measurement and gelation of MECO upon interaction with chitosan and Cu2+ ions confirmed the introduction of anionic ions into the polymer backbone. Both MEC and MECO expressed the property of surface activity hence decreasing the surface tension of water (72 mN/m), being 45.0 and 56.8 mN/m, respectively.
Co-reporter:Kristin Schumann;Annett Pfeifer ;Thomas Heinze
Macromolecular Symposia 2009 Volume 280( Issue 1) pp:86-94
Publication Date(Web):
DOI:10.1002/masy.200950610
Abstract
Summary: The synthesis of 3-mono-O-(3′-hydroxypropyl) cellulose via 3-mono-O-allyl-2,6-di-O-thexyldimethylsilyl cellulose was studied. Conversion of the double bond with 9-borabicyclo[3.3.1]nonane and subsequent alkaline oxidation lead to the 3′-hydroxypropyl group. Finally, the treatment with tetrabutylammonium fluoride trihydrate yields the complete cleavage of the protecting groups. The structure of the polymer was confirmed by one- and two dimensional NMR spectroscopic techniques. 3-mono-O-(3′-hydroxypropyl) cellulose is soluble in water and aprotic-dipolar organic media.
Co-reporter:Katrin Petzold-Welcke;Nico Michaelis;Thomas Heinze
Macromolecular Symposia 2009 Volume 280( Issue 1) pp:72-85
Publication Date(Web):
DOI:10.1002/masy.200950609
Abstract
Summary: The paper highlights the synthesis of unconventionally functionalized cellulose derivatives obtained by nucleophilic displacement (SN) reactions. The key intermediates, cellulose sulphonates, are discussed due to the fact that sulphonate groups play the major role as leaving group in SN reactions with the biopolymer. A short overview about “classical” SN reactions will be given. The main part of the review is focused on novel cellulose products in particular aminodeoxy cellulose derivatives showing monolayer formation, click chemistry with cellulose starting from deoxyazido (copper-catalyzed Huisgen reaction) yielding products with methylcarboxylate-, 2-aniline-, 3-thiophene moieties, e.g., and new selectively dendronized cellulose based materials. Structure characterization and typical applications are briefly reviewed as well.
Co-reporter:Thomas Heinze
Macromolecular Symposia 2009 Volume 280( Issue 1) pp:15-27
Publication Date(Web):
DOI:10.1002/masy.200950603
Abstract
Summary: The paper highlights recent developments in polysaccharide chemistry. Cellulose tert-butyl- and thexyldimethylsilyl ethers with degree of substitution up to 2 were accessible and comprehensively characterized by means of NMR spectroscopy. These derivatives enable the preparation of 3-O-functionalized cellulose ethers. Especially the allyl ether as protecting group at position 3 can be used for the synthesis of 2,6-di-O-methyl cellulose. Nucleophilic displacement reactions of cellulose p-toluenesulfonic acid esters with amines afforded deoxyamino celluloses that form stable monolayers on different substrates. Based on 6-deoxy-6-azido cellulose, dendrons with a focal alkyne moiety were bound via the copper(I) catalyzed Huisgen reaction. Moreover, dextran derivatives were synthesized that form stable nanoparticles useful, e.g., for the determination of the pH value in biological systems.
Co-reporter:X. Yin, A. Koschella, Th. Heinze
Reactive and Functional Polymers 2009 69(6) pp: 341-346
Publication Date(Web):June 2009
DOI:10.1016/j.reactfunctpolym.2009.02.010
Co-reporter:Dominik Fenn, Matthias Pohl, Thomas Heinze
Reactive and Functional Polymers 2009 69(6) pp: 347-352
Publication Date(Web):June 2009
DOI:10.1016/j.reactfunctpolym.2009.02.007
Co-reporter:Haisong Qi, Tim Liebert, Frank Meister, Thomas Heinze
Reactive and Functional Polymers 2009 69(10) pp: 779-784
Publication Date(Web):October 2009
DOI:10.1016/j.reactfunctpolym.2009.06.007
Co-reporter:Matthias Pohl, Nico Michaelis, Frank Meister and Thomas Heinze
Biomacromolecules 2009 Volume 10(Issue 2) pp:
Publication Date(Web):January 8, 2009
DOI:10.1021/bm801149u
Biofunctionalized surfaces based on dendronized cellulose were prepared either by embedding 6-deoxy-6-(1,2,3-triazolo)-4-polyamidoamine (PAMAM) cellulose (degree of substitution, DS 0.25), obtained by homogeneous conversion of 6-deoxy-6-azido cellulose with propargyl-PAMAM dendron via the copper-catalyzed Huisgen reaction, in a cellulose acetate (DS 2.50) matrix or by the heterogeneous functionalization of deoxy-azido cellulose film with the dendron. The amount of amino groups provided by the solid supports was determined and the covalent attachment of enzyme was proven with glucose oxidase as model enzyme after activation with glutardialdehyde. The quality of glucose oxidase immobilization was defined by determining of the specific enzyme activity, coupling efficiency, storage stability, and reproducibility. Although the heterogeneous functionalization of the deoxy-azido film yields a product that binds more enzyme compared to the blend of dendronized cellulose derivative with cellulose acetate, the coupling efficiency is comparatively small. Nevertheless, the different approaches for the preparation of biofunctionalized surfaces based on dendronized cellulose provide an excellent reproducibility and good storage stability.
Co-reporter:Matthias Pohl;Jens Schaller;Frank Meister;Thomas Heinze
Macromolecular Rapid Communications 2008 Volume 29( Issue 2) pp:142-148
Publication Date(Web):
DOI:10.1002/marc.200700628
Co-reporter:Matthias Pohl ;Thomas Heinze
Macromolecular Rapid Communications 2008 Volume 29( Issue 21) pp:1739-1745
Publication Date(Web):
DOI:10.1002/marc.200800452
Co-reporter:Stephanie Hornig, Christoph Biskup, Anja Gräfe, Jana Wotschadlo, Tim Liebert, Gerhard J. Mohr and Thomas Heinze
Soft Matter 2008 vol. 4(Issue 6) pp:1169-1172
Publication Date(Web):14 Apr 2008
DOI:10.1039/B800276B
Dialysis of a mixture of fluorescein and sulforhodamine B marked dextran derivatives yields biocompatible and tuneable nanosensors that can be used for ratiometric pH measurements.
Co-reporter:Shazia Saghir, Mohammad Saeed Iqbal, Muhammad Ajaz Hussain, Andreas Koschella, Thomas Heinze
Carbohydrate Polymers 2008 Volume 74(Issue 2) pp:309-317
Publication Date(Web):16 October 2008
DOI:10.1016/j.carbpol.2008.02.019
As revealed by NMR spectroscopy (after ultrasonic degradation) and HPLC (after total hydrolysis) an arabinoxylan (AX) containing 74.8% Xylp and 23.2% Araf was isolated from Ispaghula (Plantago ovata) by soaking the seed husk with water, extraction with aqueous sodium hydroxide and coagulation with acetic acid. The AX with a molar mass of 364,470 g/mol shows high swelling ability in water. The carboxymethylation of AX was carried out heterogeneously with sodium monochloroacetate in the presence of aqueous sodium hydroxide. The reaction parameters were varied in terms of slurry medium, molar ratio, temperature, time, and sodium hydroxide concentration. For comparative studies, carboxymethylation of arabinan was carried out. In order to determine the total degree of substitution (DS) and mole fractions of the repeating units of carboxymethyl arabinoxylan (CMAX) and of carboxymethyl arabinan, HPLC and 1H NMR spectroscopic investigations after total hydrolysis were carried out. DS values for CMAX as high as 1.81 were achieved. CMAX is water soluble starting at DS of 0.33.
Co-reporter:Holger Wondraczek ;Thomas Heinze
Macromolecular Bioscience 2008 Volume 8( Issue 7) pp:606-614
Publication Date(Web):
DOI:10.1002/mabi.200800056
Co-reporter:Holger Wondraczek ;Thomas Heinze
Macromolecular Bioscience 2008 Volume 8( Issue 7) pp:
Publication Date(Web):
DOI:10.1002/mabi.200890010
Co-reporter:Andreas Koschella;Kari Inngjerdingen;Berit S. Paulsen;Gordon A. Morris;Stephen E. Harding;Thomas Heinze
Macromolecular Bioscience 2008 Volume 8( Issue 1) pp:96-105
Publication Date(Web):
DOI:10.1002/mabi.200700120
Co-reporter:Tetsuo Kondo, Andreas Koschella, Brigitte Heublein, Dieter Klemm, Thomas Heinze
Carbohydrate Research 2008 Volume 343(Issue 15) pp:2600-2604
Publication Date(Web):13 October 2008
DOI:10.1016/j.carres.2008.06.003
The hydrogen bond systems of cellulose and its derivatives are one of the most important factors regarding their physical- and chemical properties such as solubility, crystallinity, gel formation, and resistance to enzymatic degradation. In this paper, it was attempted to clarify the intra- and intermolecular hydrogen bond formation in regioselectively functionalized 3-mono-O-methyl cellulose (3MC). First, the 3MC was synthesized and the cast film thereof was characterized in comparison to 2,3-di-O-methyl cellulose, 6-mono-O-methyl cellulose, and 2,3,6-tri-O-methyl cellulose by means of wide angle X-ray diffraction (WAXD) and 13C cross polarization/magic angle spinning NMR spectroscopy. Second, the hydrogen bonds in the 3MC film were analyzed by means of FTIR spectroscopy in combination with a curve fitting method. After deconvolution, the resulting two main bands (Fig. 3) indicated that instead of intramolecular hydrogen bonds between position OH-3 and O-5 another intramolecular hydrogen bond between OH-2 and OH-6 may exist. The large deconvoluted band at 3340 cm−1 referred to strong interchain hydrogen bonds involving the hydroxyl groups at C-6. The crystallinity of 54% calculated from the WAXD supports also the dependency of the usually observed crystallization in cellulose of the hydroxyl groups at C-6 to engage in interchain hydrogen bonding.The hydrogen bond formation in 3-mono-O-methyl cellulose was elucidated by means of 13C CP/MAS NMR- and FTIR spectroscopy. The deconvolution revealed an intramolecular hydrogen bond between the OH groups of positions 2 and 6 of adjacent repeating units of the highly crystalline polymer.
Co-reporter:Thomas Heinze;Michael Schöbitz;Matthias Pohl;Frank Meister
Journal of Polymer Science Part A: Polymer Chemistry 2008 Volume 46( Issue 11) pp:3853-3859
Publication Date(Web):
DOI:10.1002/pola.22697
Co-reporter:Sarah Köhler;Tim Liebert ;Thomas Heinze
Journal of Polymer Science Part A: Polymer Chemistry 2008 Volume 46( Issue 12) pp:4070-4080
Publication Date(Web):
DOI:10.1002/pola.22749
Abstract
Trimethylsilyl cellulose (TMSC) can be efficiently synthesized with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) by applying the ionic liquids (ILs) 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium chloride, and 1-butyl-3-methylimidazolium chloride as reaction medium, yielding pure biopolymer derivatives with degrees of substitution (DS) up to 2.89. Cosolvents, for example, chloroform, could be used to adjust the viscosity of the system and to achieve the miscibility of the components. During the synthesis of highly functionalized derivatives precipitation of the TMSC occurred, which simplifies the recycling of the IL. The high tendency of TMSC toward the formation of supermolecular structures was exploited for the formation of nanoparticles studying a simple dialysis process. Amazingly, pure cellulose nanoparticles can be obtained by dissolving TMSC in tetrahydrofurane or N,N-dimethyl acetamide and dialysis against water. FTIR spectroscopy confirmed the complete removal of the TMS functions during this process. Scanning electron microscopy, dynamic light scattering, atomic force microscopy, and particle size distribution analysis showed that cellulose particles down to a size of 170 nm are accessible in this simple manner. The nanoparticle suspensions exhibit viscosities in the range of water. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4070–4080, 2008
Co-reporter:Muhammad Ajaz Hussain;Thomas Heinze
Polymer Bulletin 2008 Volume 60( Issue 6) pp:
Publication Date(Web):2008 June
DOI:10.1007/s00289-008-0918-6
Pullulan abietic acid esters (pullulan abietates) of different degree of substitution (DS) were synthesized
homogeneously in N,N-dimethylacetamide using differently in
situactivated abietic acid derivatives. In situ activation
was achieved with p-toluenesulfonyl chloride, N,N‘-carbonyldiimidazole
and iminium chloride formed from oxalyl chloride/N,N-dimethylformamide.
The DS values of the biopolymer esters determined by acid-base titration after saponification indicated
that in situ activation with p-toluenesulfonyl
chloride is most efficient while in case of the in situ activation
with N,N‘-carbonyldiimidazole almost no polymer degradation occured.
The pullulan abietates were characterized by elemental analysis, GPC, FTIR-, 1H-
and 13C NMR spectroscopy.
Co-reporter:Thomas Heinze;Thorger Lincke;Dominik Fenn;Andreas Koschella
Polymer Bulletin 2008 Volume 61( Issue 1) pp:1-9
Publication Date(Web):2008 July
DOI:10.1007/s00289-008-0919-5
The cellulose solvent dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride trihydrate (TBAF) was
successfully applied as reaction medium for the synthesis of allyl cellulose by conversion of the polymer
with allyl chloride in the presence of solid NaOH. Samples with degree of substitution from 0.50 to 2.98
were accessible by varying the molar ratio anhydroglucose unit:allyl chloride:NaOH and reaction time. DMSO/TBAF
was found to be an efficient reaction medium for the preparation of highly functionalized samples from spruce
sulfite pulp with degree of polymerization of about 500 even in a scale of 50 g. The allyl cellulose samples
were characterized by means of FTIR- and NMR spectroscopy. Size exclusion chromatography revealed negligible
polymer degradation during synthesis and purification of the samples.
Co-reporter:Matthias Pohl;Jens Schaller;Frank Meister;Thomas Heinze
Macromolecular Symposia 2008 Volume 262( Issue 1) pp:119-128
Publication Date(Web):
DOI:10.1002/masy.200850212
Abstract
Dendronized cellulose derivatives are discussed. Regarding our own studies, novel bulky esters of cellulose were synthesized homogeneously in N,N- dimethyl acetamide/LiCl or dimethyl sulfoxide in combination with fluoride ions by conversion of the biopolymer with 3,5-dihydroxybenzoic acid based aryl polyester dendrons. The carboxylic acid moieties were efficiently activated in situ with N,N′-carbonyldiimidazole or the acid chloride was applied. Cellulose esters with values of the degree of substitution of up to 0.7 were obtained. The functionalization analyzed by NMR spectroscopy occurs not only at position 6 (primary hydroxyl group) but also the secondary one at position 2.
Co-reporter:Thomas Heinze;Susann Dorn;Michael Schöbitz;Tim Liebert;Sarah Köhler;Frank Meister
Macromolecular Symposia 2008 Volume 262( Issue 1) pp:8-22
Publication Date(Web):
DOI:10.1002/masy.200850202
Abstract
Some general comments about ionic liquids (ILs) and carbohydrates are given. The main scope of the review is to discuss the present state of the art of chemical modification of cellulose applying IL as reaction media considering own research results. ILs, namely 1-butyl-3-methylimidazolium chloride (BMIMCl), 1-ethyl- 3-methylimidazolium chloride (EMIMCl), 1-butyl-2,3-dimethylimidazolium chloride (BDMIMCl), 1-allyl-2,3-dimethylimidazolium bromide (ADMIMBr) and 1-ethyl-3- methylimidazolium acetate (EMIMAc) are solvents for cellulose (even for high molecular bacterial synthesized cellulose) and can easily be applied as reaction media for cellulose modification. We investigated the homogeneous acylation, carbanilation and silylation of the biopolymer cellulose. Under mild conditions and within short reaction time at low temperature (65 °C to 80 °C) and low excess of reagent, various cellulose esters and carbanilates, dendronized cellulose and trimethylsilyl cellulose were obtained. The DS of the cellulose derivatives can be controlled by varying the reaction time, reaction temperature and the IL used as reaction medium.
Co-reporter:Sarah Köhler;Tim Liebert;Michael Schöbitz;Jens Schaller;Frank Meister;Wolfgang Günther;Thomas Heinze
Macromolecular Rapid Communications 2007 Volume 28(Issue 24) pp:2311-2317
Publication Date(Web):22 OCT 2007
DOI:10.1002/marc.200700529
The homogeneous conversion of cellulose in the ionic liquid 1-ethyl-3-methylimidazolium acetate with 2-furoyl chloride, p-toluenesulfonyl chloride, and triphenylmethyl chloride yields surprisingly pure cellulose acetate samples in any case. From NMR spectroscopic studies, it may be concluded that during the homogeneous functionalization reactive intermediates including furane-2-carboxylic acid/acetic acid anhydride and acetic acid triphenylmethyl ester are formed leading to the cellulose acetates with DS values in the range from 0.55 to 1.86.
Co-reporter:Thomas Heinze;Matthias Pohl;Jens Schaller;Frank Meister
Macromolecular Bioscience 2007 Volume 7(Issue 11) pp:1225-1231
Publication Date(Web):21 AUG 2007
DOI:10.1002/mabi.200700103
Novel bulky esters of cellulose were synthesized homogeneously, applying the solvent systems DMA/LiCl or DMSO/TBAF, by conversion of the biopolymer with aryl polyester dendrons. The carboxylic acid moieties were efficiently activated in situ with CDI or the acid chloride was applied. Cellulose esters with DS values of up to 0.7 were obtained. The functionalization pattern was analyzed by different NMR spectroscopic techniques indicating that not only position 6 (primary hydroxyl group) but also the secondary one at position 2 was included in the reaction.
Co-reporter:Sarah Köhler;Thomas Heinze
Macromolecular Bioscience 2007 Volume 7(Issue 3) pp:307-314
Publication Date(Web):15 MAR 2007
DOI:10.1002/mabi.200600197
New solvents based on DMSO in combination with alkylammonium fluorides, in particular TBAF · 3H2O and BTMAF · H2O, were established as media for homogeneous functionalization of cellulose. Even DMSO in combination with freshly prepared, anhydrous TBAF, obtained by the reaction of tetrabutylammonium cyanide and hexafluorobenzene, dissolves cellulose. In contrast, a mixture of DMSO and tetramethylammonium fluoride does not dissolve cellulose. The solvents were characterized by capillary viscosity, which showed that a cellulose solution of DMSO/BTMAF · H2O possesses a lower viscosity at comparable cellulose concentrations compared with DMSO/TBAF · 3H2O. The determination of the degree of polymerization of the starting cellulose (microcrystalline cellulose, spruce sulfite pulp, and cotton linters), and of the regenerated samples, shows that degradation of the polymer depends on the dissolution time, temperature and on the ammonium fluoride used. The results of different homogeneous reactions including acylation and carbanilation of cellulose in the solvents were compared with those of the most-commonly-applied solvent N,N-dimethylacetamide/LiCl. The products were characterized by elemental analysis, 1H- and 13C NMR spectroscopy (additionally after perpropionylation) and FTIR spectroscopy.
Co-reporter:Thomas Heinze;Stephanie Hornig;Tim Liebert
Macromolecular Bioscience 2007 Volume 7(Issue 3) pp:297-306
Publication Date(Web):15 MAR 2007
DOI:10.1002/mabi.200600189
Well-defined multifunctionalized dextran esters bearing photo-crosslinkable and chiral groups as well as small alkyl moieties for the adjustment of the solubility were prepared from two dextran samples with different origin and molecular weight. The examination of side structures of the starting dextran was carried out by different one- and two-dimensional NMR techniques. The main synthesis path via in situ activation of furan-2-carboxylic- and pyroglutamic acid with CDI under mild conditions gives highly functionalized dextran derivatives possessing a degree of polymerization in the range of the starting polysaccharide. The subsequent reaction with propionic anhydride leads to completely substituted, CHCl3 soluble derivatives useful for the determination of the particular degree of substitution. By variation of the molar ratios of polymer to reagent with photo-crosslinkable- and chiral moieties during the reaction and even by subsequent peracylation, multifunctional dextran derivatives with adjustable properties like the hydrophilic/hydrophobic balance were obtained that may form biocompatible spherical nanoparticles.
Co-reporter:Stephanie Hornig;Tim Liebert;Thomas Heinze
Polymer Bulletin 2007 Volume 59( Issue 1) pp:65-71
Publication Date(Web):2007 June
DOI:10.1007/s00289-007-0749-x
Sulfur containing dextran and β-cyclodextrin derivatives were synthesised as alternitive coating materials for gold surfaces. The esterification of the carbohydrates with thiophene carboxylic acids and α-lipoic acid was carried out in DMSO by in situ activation of the acids with N,N’-carbonyldiimidazole. The thiophene carboxylic acids vary in the position of the sulfur atom and the spacer between the thiophene and the carboxylic group. DS values ranging from 0.44 to 2.04 were accessible depending both on the carbohydrate and the acid used. Insoluble derivatives were obtained by the conversion of α-lipoic acid with the carbohydrates. The structure of the derivatives soluble in DMSO and DMF was examined by IR- and NMR spectroscopy. Furthermore, subsequent acylation reveals a useful tool for the determination of the degree of substitution of the thiophene derivatives additionally to elemental analysis.
Co-reporter:Katrin Schwikal;Thomas Heinze
Polymer Bulletin 2007 Volume 59( Issue 2) pp:161-167
Publication Date(Web):2007 September
DOI:10.1007/s00289-007-0755-z
The reaction of glucuronoxylan from birch wood with 2-chloro-N,N-dimethylethyl-, 2-chloro-N,N-diethylethyl- and 2-chloro-N,N-diisopropylethylamine hydrochloride in 1,2-dimethoxyethane as slurry medium was investigated. The degree of substitution (DS, up to 1.54) of the products could be controlled by adjusting the molar ratio of biopolymer to reagent and depends on the reagent used. The structure of the novel xylan derivatives was confirmed by means of DEPT(135) NMR spectroscopy. The solubility of the polymers with different alkyl moieties possesses a pH value-dependency as studied by turbidity measurements.
Co-reporter:Sarah Köhler;Thomas Heinze
Cellulose 2007 Volume 14( Issue 5) pp:489-495
Publication Date(Web):2007 October
DOI:10.1007/s10570-007-9138-8
The ionic liquid 1-N-butyl-3-methylimidazolium chloride ([C4mim]+Cl−) was investigated as reaction media for the homogeneous acylation of cellulose with 2-furoyl chloride in the presence of pyridine. The preparation of cellulose furoate depending on the reaction conditions, the cellulose type and the pyridine content was studied. Cellulose furoates with a degree of substitution in the range from 0.46 to 3.0 were accessible, i.e., under mild conditions, with a low excess of reagent and in a short reaction time. The products were characterized by elemental analysis, perpropionylation, 1H- and 13C NMR spectroscopy and FTIR spectroscopy.
Co-reporter:Susann Barthel and Thomas Heinze
Green Chemistry 2006 vol. 8(Issue 3) pp:301-306
Publication Date(Web):22 Dec 2005
DOI:10.1039/B513157J
Ionic liquids (ILs) namely 1-N-butyl-3-methylimidazolium chloride ([C4mim]+Cl−), 1-N-ethyl-3-methylimidazolium chloride ([C2mim]+Cl−), 1-N-butyldimethylimidazolium chloride ([C4dmim]+Cl−) and 1-N-allyl-2,3-dimethylimidazolium bromide ([Admim]+Br−) were investigated as solvent for the homogeneous acylation and carbanilation of the biopolymer cellulose. Cellulose acetates with a degree of substitution (DS) in the range from 2.5 to 3.0 are accessible within 2 h at 80 °C in a complete homogeneous procedure. The acylation of cellulose with the fatty acid chloride lauroyl chloride leads to cellulose laurates with DS from 0.34 to 1.54. The reaction starts homogeneously and continues heterogeneously. The synthesis of cellulose carbanilates succeeds in the ionic liquid [C4mim]+Cl− without any catalyst. The new homogeneous path gives pure cellulose carbanilates. All reactions are carried out under mild conditions, low excess of reagent and a short reaction time. The reaction media applied can be easily recycled and reused.
Co-reporter:Claudia Hänsch;Thomas Heinze;Tim Liebert
Macromolecular Rapid Communications 2006 Volume 27(Issue 3) pp:208-213
Publication Date(Web):23 JAN 2006
DOI:10.1002/marc.200500686
Summary: The copper-catalyzed Huisgen reaction as a typical example of click chemistry was realized with the polysaccharide cellulose for the first time. The generality, selectivity, and the efficiency of click chemistry perfectly fit the requirements of polysaccharide modification, which is demonstrated by the introduction of triazole-spacer bound functional groups, i.e., carboxylic ester, thiophene, and aniline moieties. Azide moieties introduced into cellulose via the tosyl derivative were simply transferred with ethynyl compounds under Cu(I) catalysis and mild and easily applicable conditions. Hydrolytically stable cellulose derivatives soluble in organic solvents, e.g., DMSO or DMF with DS up to 0.9 are obtained. The triazole substituted cellulose derivatives were characterized by elemental analysis, FTIR, 1H NMR, and 13C NMR spectroscopies and show no impurities or substructures resulting from side reactions.
Co-reporter:Kerstin Schlufter;Hans-Peter Schmauder;Thomas Heinze;Susann Dorn
Macromolecular Rapid Communications 2006 Volume 27(Issue 19) pp:1670-1676
Publication Date(Web):27 SEP 2006
DOI:10.1002/marc.200600463
Summary: Bacterial cellulose (BC), a unique type of cellulose, with high degree of polymerization of 6 500 could be dissolved easily in the ionic liquid 1-N-butyl-3-methylimidazolium chloride. For the first time, well-soluble BC acetates and carbanilates of high degree of substitution (up to a complete modification of all hydroxyl groups) were accessible under homogeneous and mild reaction conditions. Characterization of the new BC derivatives by NMR and FTIR spectroscopy shows an unexpected distribution of the acetyl moieties in the order O-6 > O-3 > O-2.
Co-reporter:Timo Leermann;Andreas Koschella;Meinolf Brackhagen;Thomas Heinze
Journal of Applied Polymer Science 2006 Volume 100(Issue 3) pp:2142-2150
Publication Date(Web):17 FEB 2006
DOI:10.1002/app.23600
Sulfonic acid esters of differently linked polysaccharides including cellulose, dextran, lichenan, and pullulan were synthesized homogeneously applying N,N-dimethylacetamide/LiCl as the solvent. The dependence of the degree of substitution (DS) on the molar ratio of repeating unit to sulfonic acid chloride and on the structure of the reagent (benzene-, p-toluene-, 4-chlorobenzene-, 2,4-dinitrobenzene-, 2,4,6-trimethylbenzene-, and 2,4,6-triisopropylbenzene sulfonic acid chloride), as well as on the polysaccharide, was studied. DS values in the range of 0.2–2.3 were obtained. Bulky and electron withdrawing substituents on the aromatic ring inhibited ester formation. None of the sulfonic acid chlorides applied showed distinct regioselectivity. The polysaccharide sulfonic acid esters were soluble in organic solvents depending on the type of substituent and the degree of substitution. The molecular structure of the new polymers was confirmed by elemental analysis, FTIR, and 13C-NMR spectroscopy. Subsequently, nucleophilic displacement reactions were carried out, which showed that the reactivity of the primary sulfonic acid ester group was higher than that of the secondary ones. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2142–2150, 2006
Co-reporter:Thomas Heinze;Jürgen Engelhardt;Klaus Nachtkamp;Meinolf Brackhagen;Andreas Koschella
Macromolecular Symposia 2006 Volume 244(Issue 1) pp:74-82
Publication Date(Web):16 JAN 2007
DOI:10.1002/masy.200651206
Summary: Ammonium group containing cellulose derivatives are prepared from homogeneously synthesized cellulose p-toluenesulfonic acid esters (tosyl cellulose) by conversion with sodium azide and subsequent reduction of the azido moiety applying NaBH4/CoBr2/2,2′-bipyridine as reagent. Regarding the tosylation, cellulose samples of different degree of polymerization and hemicellulose content possess a different reactivity. The deoxyamino cellulose is water soluble in the protonated state. Elemental analysis, FTIR- and NMR spectroscopy were carried out to analyze the degree of substitution and functionalization pattern. It was also studied to synthesize deoxyazido celluloses without isolation of the tosyl cellulose. However, a predominant formation of deoxychloro moieties occurs.
Co-reporter:Andreas Koschella;Dominik Fenn;Nicolas Illy;Thomas Heinze
Macromolecular Symposia 2006 Volume 244(Issue 1) pp:59-73
Publication Date(Web):16 JAN 2007
DOI:10.1002/masy.200651205
Summary: The paper reviews recent developments in synthesis and characterization of regioselectively functionalized cellulose derivatives. It demonstrates the importance of protecting groups like triphenylmethyl- and thexyldimethylsilyl (TDMS) ethers in cellulose chemistry. The protected cellulose derivatives can be used for the preparation of 2,3-O-functionalized polymers. Moreover, the TDMS group opens up the synthesis of 3-O-ethers of cellulose that possess interesting properties in terms of structure in solution, water-solubility, and thermoreversible gelation.
Co-reporter:Stephanie Hornig;Thomas Heinze;Stephanie Hesse;Tim Liebert
Macromolecular Rapid Communications 2005 Volume 26(Issue 24) pp:1908-1912
Publication Date(Web):28 NOV 2005
DOI:10.1002/marc.200500631
Summary: Applying a dialysis process, new nanoparticles based on well-defined dextran esters of furan-2-carboxylic- and pyroglutamic acids were prepared, which can undergo cross-linking by UV irradiation. The highly functionalized products (total DS > 2) avoid the collapse of nanoparticles due to the prevention of hydrogen bond formation. The major fraction of the dextran ester nanospheres exhibits narrow size distribution down to 250 nm as mean diameter investigated by SEM.
Co-reporter:Jens Schaller;Thomas Heinze
Macromolecular Bioscience 2005 Volume 5(Issue 1) pp:58-63
Publication Date(Web):5 JAN 2005
DOI:10.1002/mabi.200400136
Summary: Novel 2,3-O-hydroxyethyl- and 2,3-O-hydroxypropyl cellulose products were synthesized by heterogeneous etherification of 6-O-(4-monomethoxytrityl) cellulose (MMTC). Due to the very hydrophobic character of MMTC, the reaction was successful in the presence of anionic and non-ionic detergent in the reaction mixture yielding the 2,3-O-cellulose ethers with a molar degree of substitution (MS) varying between 0.25 and 2.00 after detritylation. The products were characterized by means of 1H and 13C NMR spectroscopy including two-dimensional methods. The 2,3-O-hydroxypropyl cellulose samples are soluble in water at a MS as low as 0.8. The spectroscopic studies showed that the unusual solubility results from a preferred substitution of hydroxy groups of the anhydroglucose unit while the newly formed hydroxy moieties are included in the reaction to a minor extent only. In contrast, conventionally synthesized hydroxypropyl cellulose is soluble in water starting at a MS of about 4.0 because of the formation of oxyethylene side chains.
Co-reporter:Thomas Heinze;Katrin Schwikal;Susann Barthel
Macromolecular Bioscience 2005 Volume 5(Issue 6) pp:520-525
Publication Date(Web):10 JUN 2005
DOI:10.1002/mabi.200500039
Summary: The application of different ionic liquids (IL), namely 1-N-butyl-3-methylimidazolium chloride ([C4mim]+Cl−), 3-methyl-N-butyl-pyridinium chloride and benzyldimethyl(tetradecyl)ammonium chloride were investigated as solvents for cellulose. The ILs used have the ability to dissolve cellulose with a degree of polymerization in the range from 290 to 1 200 to a very high concentration. Using [C4mim]+Cl−, no degradation of the polymer appears. By 13C NMR measurement it was confirmed that this IL is a so-called non-derivatizing solvent. [C4mim]+Cl− can be applied as a reaction medium for the synthesis of carboxymethyl cellulose and cellulose acetate. Without using any catalyst, cellulose derivatives with high degree of substitution could be prepared.
Co-reporter:L.A. Ramos, E. Frollini, Th. Heinze
Carbohydrate Polymers 2005 Volume 60(Issue 2) pp:259-267
Publication Date(Web):6 May 2005
DOI:10.1016/j.carbpol.2005.01.010
The new cellulose solvent dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride (TBAF) was applied as reaction medium for the carboxymethylation of mercerized cellulose from sisal and cotton linters. The reaction parameters studied were the molar ratio of reagent and NaOH to anhydroglucose unit (AGU) and the addition of the NaOH either as an aqueous solution or as solid particles. Size Exclusion Chromatography results (SEC) indicated that the dissolution medium and/or derivatizing method used in the present work causes a certain depolymerization on the cellulose chains The pattern of substitution within the AGU and along the polymer chains of the carboxymethylcellulose (CMC), which was analyzed by 1H NMR spectroscopy and HPLC after acidic depolymerization of the CMC, is in the order O-6>O-2≥O-3. With regard to the mole fractions of the different repeating units, samples prepared using aqueous NaOH possess a statistic content, while by using solid NaOH a deviation from statistically calculated values was observed. As a consequence of the non-statistics, the solubility in water of these samples starts at a DS 0.85, while conventionally prepared CMC are water-soluble at a DS as low as 0.4.
Co-reporter:S. Hesse Dr.;S. Hornig;T. Liebert Dr. Dr.
Chemie Ingenieur Technik 2005 Volume 77(Issue 8) pp:
Publication Date(Web):10 AUG 2005
DOI:10.1002/cite.200590343
Co-reporter:Tim Liebert;Stephanie Hornig;Stephanie Hesse;Thomas Heinze
Macromolecular Symposia 2005 Volume 223(Issue 1) pp:253-266
Publication Date(Web):28 APR 2005
DOI:10.1002/masy.200550518
Microscopy has proved to be a valuable tool for the investigation of supermolecular structures of cellulose derivatives. Thus, with AFM it was possible to show that statistically functionalized derivatives (degree of substitution below 3) form specific aggregates called fringed micelles. In contrast, derivatives with a non-statistic distribution exhibit a more network-like structure as known for galactomannans consisting of block-like structures. If samples are prepared by deposition of dilute solutions of polyelectrolytes on mica and drying at elevated temperature, the formation of nanorings is observed. In addition, AFM and REM were applied to investigate the morphology of membranes prepared of cellulose esters with unsaturated substituents. It was shown that cross-linking of the polymer chains in the membranes does not lead to a change in the nanostructure of the surface, i.g., the surface roughness and the pore sizes were not modified.
Co-reporter:Tim Liebert;Katy Pfeiffer;Thomas Heinze
Macromolecular Symposia 2005 Volume 223(Issue 1) pp:93-108
Publication Date(Web):28 APR 2005
DOI:10.1002/masy.200550507
Carbamoylation of cellulose esters (CE) and investigation of the mixed derivatives obtained with NMR spectroscopy represents a useful analytical tool for the determination of the degree of substitution (DS) and analysis of the distribution of substituents on the level of the anhydroglucose unit (AGU). Especially the carbethoxymethylcarbamoylation and the ethylcarbamoylation of CE combined with 1H NMR spectroscopy are efficient and inexpensive ways to gain information on the over-all DS and partial DS values in position 2, 3, and 6 of the AGU. Complete subsequent phenylcarbamoylation can be achieved even for CE with bulky substituents, e.g., adamantanecarboxylic acid esters. In addition to NMR experiments the carbamoylated CE were studied by HPLC after complete chain degradation. Carbethoxymethylcarbamoylation has turned out to be the most useful tool for this path. Chromatograms comparable to carboxymethylated cellulose (CMC) were obtained, which can be exploited to calculate the mole fractions of the basic building units (un-, mono-, di- and tri-substituted glucoses) of the polymer. Comparison with statistic calculations gave a first hint on the distribution of substituents along the polymer chain. For a commercial cellulose diacetate a statistic pattern of substitution was determined.
Co-reporter:Andreas Koschella;Thomas Heinze
Macromolecular Symposia 2005 Volume 223(Issue 1) pp:13-40
Publication Date(Web):28 APR 2005
DOI:10.1002/masy.200550502
This review article deals with the technically important carboxymethyl ethers of cellulose and starch. Recent developments of synthesis, characterization, and application are presented considering adequately own research work in this field. In particular, the structure characterization by means of chromatographic (HPLC) and NMR-spectroscopic techniques as well as commercially important synthesis paths and alternative methods are described.
Co-reporter:Muhammad A. Hussain;Tim Liebert;Thomas Heinze
Macromolecular Symposia 2005 Volume 223(Issue 1) pp:79-92
Publication Date(Web):28 APR 2005
DOI:10.1002/masy.200550506
New paths for the fast and reliable analysis of cellulose esters (CE) via subsequent functionalization and 1H NMR spectroscopy were studied. Perpropionylation of the CE is an inexpensive and efficient method. For cellulose diacetates used as representative ester well resolved 1H NMR spectra were obtained, which can be used for the calculation of the over all degree of substitution (DS) and the partial DS values at position 2, 3, and 6. No transesterification occurs during the subsequent acylation and a standard deviation of S2 = 1.32 x 10−4 was found for a series of experiments. In case of more complex ester structures especially with extended aliphatic moieties per-4-nitrobenzoylation need to be applied prior to NMR measurements. The spectra obtained can be completely assigned and applied for the calculation of DS values.
Co-reporter:W.-M. Kulicke
Macromolecular Symposia 2005 Volume 231(Issue 1) pp:47-59
Publication Date(Web):12 JAN 2006
DOI:10.1002/masy.200590024
Modern blood plasma volume expanders consist of water-soluble polysaccharides that are compatible with the human body. They are more effective for the treatment of intravasal volume deficiency compared to synthetic polymers. These colloidal blood plasma volume expanders, for example pullulan, dextran or hydroxyethyl starch (HES) are used in blood isotonic electrolyte solutions. HES has the lowest tendency to remain in the liver or other organs of the human body in comparison to other expanders.
The knowledge of the molar mass and coil dimensions as well as their distribution are essential, since products of low molar masses do not have the desired effect and parts of large molar masses can lead to an anaphylactic shock. Injection of HES enhances the microcirculation and leads to a better oxygen transport into the tissue and the muscle. Because of this, HES was identified as a doping agent in 02/2002. In addition to this it will be shown that starch acetates have an even better physiological compatibility and are an interesting alternative to HES. We will present investigations on the shelf life of a new acetyl starch, which may be an alternative to the blood plasma expanders used to date.
Co-reporter:Katrin Petzold;Katrin Schwikal;Wolfgang Günther;Thomas Heinze
Macromolecular Symposia 2005 Volume 232(Issue 1) pp:27-36
Publication Date(Web):15 FEB 2006
DOI:10.1002/masy.200551404
The hemicellulose xylan is a polysaccharide that occurs in nature in enormous amount in various one year- and perennial plants having different structures and molecular masses. Versatile ways to generate bio-based functional polymers result from the chemical modification of this biopolymer. In our research, xylans from various resources like birch-, beech-, and eucalyptus wood and from oat husk, rye bran, and corn cob were used to investigate the important method of carboxymethylation in detail. Different activation procedures were elaborated to synthesize carboxymethyl xylan. One step reactions lead to products with a degree of substitution (DS) from 0.13 to 1.22 in dependence on the molar ratio of anhydroxylose unit (AXU) to reagent. Two step syntheses yielded DS values up to 1.65. Carboxymethyl xylans are water soluble at a DS of 0.3. The solutions have different clearness depending on the provenience. NMR spectroscopy and HPL chromatography were applied to characterize the carboxymethyl xylans in detail.
Co-reporter:Stephanie Hesse;Thomas Heinze;Tim Liebert
Macromolecular Symposia 2005 Volume 232(Issue 1) pp:57-67
Publication Date(Web):15 FEB 2006
DOI:10.1002/masy.200551407
Furan-2-carboxylic acid esters of xylan, cellulose, curdlan, dextran, and starch were synthesized and studied regarding their film formation abilities. The polysaccharide esters were utilized to prepare films of different appearance. To investigate supermolecular structures of the biopolymer derivatives, atomic force- and scanning electron microscopy were applied. The surface roughness and the macro-pore size and -distribution of the polysaccharide ester films were characterized. Starch furan-2-carboxylic acid ester (starch furoate) did not show film formation. In contrast, dextran furoates are very well suitable for the surface coating of inorganic compounds while the xylan-, cellulose-, and curdlan derivatives yield self-supporting films with different surface characteristics.
Co-reporter:Tim Liebert;Muhammad Ajaz Hussain;Thomas Heinze
Macromolecular Rapid Communications 2004 Volume 25(Issue 9) pp:916-920
Publication Date(Web):21 APR 2004
DOI:10.1002/marc.200300308
Summary: Carboxylic acids were efficiently activated with N,N′-carbonyldiimidazole (CDI) and applied for the acylation of cellulose under homogeneous conditions using dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride trihydrate (TBAF) as solvent. The simple and elegant method is a very mild and easily applicable tool for the synthesis of pure aliphatic, alicyclic, bulky, and unsaturated cellulose esters with degrees of substitution of up to 1.9. Products are soluble in organic solvents, e.g., DMSO or N,N-dimethylformamide (DMF). The cellulose esters were characterized by elemental analysis, FT-IR, 1H and 13C NMR spectroscopy and show no impurities or substructures resulting from side reactions.
Co-reporter:Elisabete Frollini;Thomas Heinze;Beatriz A. P. Ass
Macromolecular Bioscience 2004 Volume 4(Issue 11) pp:1008-1013
Publication Date(Web):4 NOV 2004
DOI:10.1002/mabi.200400088
Summary: The novel solvent dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride trihydrate (TBAF · 3H2O) was studied for acetylation of linters cellulose. In order to control the degree of substitution (DS), acetylation of the macromolecule was carried out at different reaction time and temperature, molar ratio of reactants, as well as under variation of the concentration of TBAF · 3H2O in solution. Cellulose acetate (CA) was accessible with DS ranging from 0.43 to 2.77. The change in concentration of TBAF · 3H2O in DMSO showed a strong influence on DS. The most appropriate reaction conditions for acetylation of linters cellulose regarding maximal DS were evaluated. The structure of the CA was characterized by means of FTIR and NMR spectroscopy. The solubility of the CA depends not only on the DS but also on the reaction conditions applied, indicating a different distribution of acetate moieties both within and between polymer chains.
Co-reporter:Thomas Heinze;Tim Liebert
Macromolecular Symposia 2004 Volume 208(Issue 1) pp:167-238
Publication Date(Web):21 APR 2004
DOI:10.1002/masy.200450408
The chemical structure of cellulose acetates (CA), different synthesis paths, analysis strategies and the correlation of these structural features with properties, especially with the solubility are summarized. Alternative paths, in particular homogeneous procedures, for the synthesis of CA are described focusing on the application of new media and the in situ activation of acetic acid. The preparation of selectively substituted CA is reviewed including the defined hydrolysis under acidic or basic conditions. Strategies for the structure analysis by means of 1H- and 13C-NMR spectroscopy and by means of chromatographic methods are discussed. In addition, the preparation and the application of a variety of mixed CA ethers and esters are described.
Co-reporter:Waldemar Lazik;Carsten Grote;Thomas Heinze
Macromolecular Rapid Communications 2003 Volume 24(Issue 16) pp:927-931
Publication Date(Web):28 OCT 2003
DOI:10.1002/marc.200300042
New tartaric acid starch ethers have been synthesized applying starch sources of different amylose content. The reactions were carried out heterogeneously in ethanol/water mixtures with cis-disodiumepoxysuccinate as etherifying reagent leading to products of a degree of substitution (DS) up to 0.3. The molecular structure of the new starch ethers was evaluated by elemental analysis, FTIR and 13C NMR spectroscopy. Preliminary studies using a convenient titration method indicate a high binding capacity for Ca2+ ions which is dependent on the starch source and DS.
Co-reporter:T. Liebert, W.-M. Kulicke, Th. Heinze
Reactive and Functional Polymers (January 2008) Volume 68(Issue 1) pp:1-11
Publication Date(Web):January 2008
DOI:10.1016/j.reactfunctpolym.2007.10.025
Co-reporter:Thomas Elschner, Franziska Obst, Karin Stana-Kleinschek, Rupert Kargl, Thomas Heinze
Carbohydrate Polymers (1 April 2017) Volume 161() pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.carbpol.2016.12.038
Highlights•Synthesis of highly functionalized dextran furfuryl carbamates requires trimethylamine.•Dextran furfuryl carbamates with random or regioselective substitution patterns are accessible.•Dextran maleimido carbonate is synthesized mildly and efficiently.•Quantitative removal of the protecting group in bulk or thin film is evidenced.Carbonic acid derivatives of dextran possessing furfuryl- and maleimido moieties were synthesized and processed into thin films by spin coating. First, products with different degrees of substitution (DS) of up to 3.0 and substitution patterns were obtained and characterized by NMR- and FTIR spectroscopy, as well as elemental analysis. Thin films possessing maleimide groups were obtained by spin coating of maleimido dextran (furan-protected) and dextran furfuryl carbamate that was converted with bismaleimide. The removal of the protecting group (furan) on the thin film was monitored by QCM-D and compared with gravimetric analysis of the bulk material. Film morphology and wettability were determined by means of AFM and contact angle measurements.
Co-reporter:Stephanie Hornig, Thomas Heinze, C. Remzi Becer and Ulrich S. Schubert
Journal of Materials Chemistry A 2009 - vol. 19(Issue 23) pp:NaN3840-3840
Publication Date(Web):2009/05/01
DOI:10.1039/B906556N
Nanoprecipitation is applied for the first time as a general concept for manufacturing nanoparticles of versatile hydrophobic polymer classes. As a result, polymer molecules self-assemble into nanospheres or irregularly shaped nanoparticles during the transition from the dissolved state to the solid state while using different solvents and methods for the conversion.
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![TRICYCLO[3.3.1.13,7]DECANE-1-CARBOXYLIC ACID](http://img.cochemist.com/ccimg/42900/42862-36-2.png)
![TRICYCLO[3.3.1.13,7]DECANE-1-CARBOXYLIC ACID](http://img.cochemist.com/ccimg/42900/42862-36-2_b.png)
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