This article reports a comparative study on the synthesis, self-assembly, and photophysical properties of perylene diimides (PDIs) symmetrically tethered with long alkyl chains or polyhedral oligomeric silsesquioxanes (POSS) at the imide position and/or bromo substitutions at 1,7-positions of the bay area. This series of samples include dodecyl–PDIH–dodecyl (1), dodecyl–PDIBr–dodecyl (2), POSS–PDIH–POSS (3), and POSS–PDIBr–POSS (4). In solution, the PDIs with bromine substitution at bay area (2, 4) exhibit red-shifted absorption maximum compared to those without (1, 3), which is consistent with a twisted perylene chromophore as revealed by molecular simulation. Similar bathochromatic shift was observed on the solid crystal state emission of 2 as compared to 1. However, in crystals, the emission spectrum of 4 exhibits a seemingly hypochromatic shift relative to that of 3, which could be rationalized by their packing in the crystals. The bromo substitution is believed to partially quench the fluorescence and the relatively loose packing of the twisted π-plane of 4 may not be able to confine π-plane in place, leaving multiple pathways for fluorescent quenching rather than red-shifted emission. While both 3 and 4 exhibit a unique dimer packing scheme, the dimers have quite different longitudinal offset and transverse offset of the π-plane. The longitudinal offset in dimers of 4 is so large that the naphthalene moieties in the dimer almost adopt a face-to-face arrangement and their mutual interactions are considered relatively independent. All these contribute to the less red-shifted fluorescent emission and the lower fluorescent yields in crystals of 4 relative to 3 as compared to that in solution. The study shall shed light into the complicated mutual interactions among intrinsic electronic structure, microscopic molecular packing, and the macroscopic optoelectronic properties.

In this work, an amphiphilic perylene diimide (1,7-TEG-PDI-C12) that bears two hydrophilic triethylene glycol (TEG) chains at its bay position, and two hydrophobic dodecyl chains at its imide position was synthesized to identify the roles of concentration and H-bonding on the self-assembly morphology of the amphiphilic PDI. Since 1,7-TEG-PDI-C12 was prepared from the reaction of two bifunctional reactants, TEG and N,N′-bis(n-dodecyl)-1,7-dibromo-perylene-3,4:9,10-tetracarboxylic diimide, careful choices of solvent, base, and the stoichiometry of crown ether and base were found to be critical in reaching high reaction yield under mild conditions. TEM and SEM results revealed the abundant concentration-dependent self-assembly morphologies of 1,7-TEG-PDI-C12. Characterization results including UV-vis, fluorescence, NMR, IR and XRD analysis show that the formation of the self-assembled structure is a synergetic result of the intermolecular π–π interaction and H-bonding of 1,7-TEG-PDI-C12.

This article reports the enhanced photoluminescent properties observed in the crystals of a cube-plane-cube shape amphiphile composed of perylene diimide (PDI) tethered with polyhedral oligomeric silsesquioxanes (POSS) at the imide position via either rigid or flexible linkages (POSS-PDI-POSS). The fluorescence quantum yields (Φf) of the conjugates in crystal (∼0.48) are much higher than that of the more amorphous samples (∼0.17) and that of the reference compound without pendant POSS cage (∼0.12). The enhancement was understood in three ways. First, their self-assembly behaviors in gaseous phase were studied by tandem mass spectrometry coupled with traveling wave ion mobility separation; second, their self-assembly behaviors in solution were revealed by concentration- and solvent-dependent experiments using UV/vis absorption and fluorescence spectrometry; and third, the molecular packing in crystals was determined by wide angle X-ray diffraction and transmission electron microscope. The results demonstrate the conjugates' strong tendency toward dimer formation in solution and show a unique molecular packing of discrete dimeric motifs in the solid states. It suggests that the high Φf of these conjugates can be attributed to the discontinuous π–π stacking, which results in a weaker electron interaction between the dimers, and the relatively fixed position of the PDI, which prohibits the common structural relaxation of PDIs π-planes.

A series of poly(styrene-co-divinylbenzene)/silver nanoparticle (P(St-DVB)/AgNP) composite microspheres with tunable porosity were synthesized by seed swelling polymerization in one pot using linear polystyrene seeds as templates and nanosized organic soluble AgNPs as the silver source. The polymerization of styrene and divinylbenzene took place inside the seed particles and AgNPs were dispersed directly into the mixture of styrene and divinylbenzene during the polymerization. The morphology properties of P(St-DVB)/AgNPs microspheres were characterized by optical microscope, scanning electron microscope (SEM) and nitrogen adsorption/desorption. The influencing parameters on the morphology of the microspheres, including feed ratio of styrene (monomer) and divinylbenzene (crosslinker), addictive amount of AgNPs and the variety of the porogens were systematically investigated. The porosity of the composite microspheres could be tuned from nonporous to mesoporous and to macroporous by control over these parameters. Meanwhile, AgNPs loading dispersity of the composite microspheres was characterized by transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS), SEM and thermogravimetric analysis (TGA). TEM, EDS and SEM results demonstrated that the AgNPs had been loaded both inside and on the surface of the microspheres. The sizes of the loaded AgNPs were influenced by the addictive amount of AgNPs and the kinds of porogens used in the polymerization. Moreover, compared to the P(St-DVB) microspheres, the Ag-loading composite microspheres synthesized in this paper exhibited excellent catalytic activity and reusability in the degradation of methylene blue in the presence of NaBH4.

To prepare lipophilic α-zirconium phosphate with high grafting ratio and thermal stability (OZrP-HT) and explore its potential application in thermal-plastic polymers, a novel method was developed by surface lipophilicity enhancement strategy. The commercial α-zirconium phosphate (α-ZrP) was pre-intercalated by n-propylamine (PA) and grafted by silane coupling agents. Then the pre-intercalated PA was removed by heat-treatment, and the obtained OZrP-HT was utilized to fabricate the phosphorous-containing polyester (P-co-PET)/OZrP-HT nanocomposites by melt-blending method. The prepared OZrP-HT and P-co-PET/OZrP-HT nanocomposites were characterized by Wide Angle X-ray Diffraction (WAXD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Transmission Electron Microscope (TEM), etc. The results show that OZrP-HT with high grafting ratio (13.78 wt%) and thermal stability (Tonset=368 °C) was successfully prepared via this novel method and was uniformly intercalated by P-co-PET molecular chains. OZrP-HT had no significant effect on the fiber processability of P-co-PET polymer, and flame retardant properties of (P-co-PET)/OZrP-HT nanocomposites were improved. This method may be suitable for organic modification of general inorganic layered compounds and could extend the potential applications in thermo-plastic polymers.

•The conductive composite fibers were fabricated via in situ polymerization of EDOT on functionalized PP fibers.•The grafted PAA on PP fibers enhanced the adhesion of PEDOT with the PP substrate.•The conductive composite fibers exhibited high reversibility and sensitivity in response to HCl and NH3 gas.Conductive composite fibers were successfully fabricated by coating poly(3,4-ethylenedioxythiophene) (PEDOT) layers on the surface of polypropylene-graft-poly(acrylic acid) (PP-g-PAA) fibers through in situ chemical oxidative polymerization. It was found that the adhesion between the conductive PEDOT layers and the modified PP fiber substrates was significantly enhanced due to the electrostatic attractions between PEDOT chains and carboxylic groups of grafted PAA. In this study, we investigated the influence of the 3,4-ethylenedioxythiophene (EDOT) concentration and the oxidant species on the electrical conductivity of the composite fibers, and the result show that the maximum conductivities of PP-g-PAA/PEDOT composite fibers prepared with FeCl3 and iron(III) p-toluenesulfonate (FepTS) as oxidants reached 0.069 S/cm and 10.09 S/cm, respectively. The composite fibers were applied as a sensor for HCl and NH3 gas detection and exhibited a rapid and reversible response. The influence of the oxidant species on the sensing properties for HCl and NH3 gas detection is further discussed, and some features such as fast response time (less than 2 s) and high relative resistance changes (63% for HCl and 110% for NH3 gas) were achieved.

•Quartz fibres (QFs) were modified using a sol-gel method with tetraethoxysilane (TEOS) and 3-methacryloxypropyltrimethoxysilane (γ-MPS) as precursors.•The dental posts reinforced with modified QFs demonstrated an improvement of 108.3% and 89.6% for the flexural strength and flexural modulus, respectively, compared with dental posts reinforced with untreated QFs.•The sorption and solubility of the dental posts were studied by immersing the posts in artificial saliva (AS) for 4 weeks, and yielded favourable results.In this study, quartz fibres (QFs) surface modification using a sol-gel method was proposed and dental posts reinforced with modified QFs were produced. A silica sol (SS) was prepared using tetraethoxysilane (TEOS) and 3-methacryloxypropyltrimethoxysilane (γ-MPS) as precursors. The amount of γ-MPS in the sol-gel system was varied from 0 to 24 wt.% with a constant molar ratio of TEOS, ethanol, deionized water, and HCl. Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and contact angle (CA) measurements were used to characterize the modified QFs, which confirmed that SS had successfully coated the surface of QFs. SEM images showed good interfacial bonding between the modified QFs and the resin matrix. The results of three-point bending tests of the fibre reinforced composite (FRC) posts showed that the QFs modified by SS with 12 wt.% γ-MPS presented the best mechanical properties, demonstrating improvements of 108.3% and 89.6% for the flexural strength and flexural modulus, respectively, compared with untreated QFs. Furthermore, the sorption and solubility of the prepared dental posts were also studied by immersing the posts in artificial saliva (AS) for 4 weeks, and yielded favourable results. This sol-gel surface modification method promises to resolve interfacial bonding issues of fibres with the resin matrix, and produce FRC posts with excellent properties.