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Two anions (dodecylbenzenesulfonate anion and stearate anion) are employed to synthesize intercalated layered double hydroxides (LDH) by co-precipitation method. Then the intercalated LDHs are incorporated in the casting solutions of chloromethylated polysulfone (CMPSF) for fabricating quaternized polysulfone/LDH nanocomposite membranes. Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and mastersizer laser particle size analysis are used to characterize the structure and morphology of LDHs and membranes. The properties of the composite membranes including water uptake, mechanical property, thermal stability, and ionic conductivity are investigated. Compared with other anion exchange membranes, both nanocomposite membranes containing 5% LDH sheets displayed better balanced performance. They exhibit the ionic conductivity of 3.58 × 10−2 S cm−1 and 3.86 × 10−2 S cm−1 at 60°C, respectively. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers

A novel strategy for fabricating nanocomposite anion exchange membranes (AEM), which can construct self-assembled ionic channels via in situ Menshutkin reaction, is proposed. The TEM image of a nanocomposite AEM based on chloromethylated polysulfone (CMPSF) and functionalized polyhedral oligomeric silsesquioxane (POSS) confirms the existence of core-shell clusters. The ionic conductivity of these nanocomposite AEMs shows a notable increase when the content of functionalized POSS exceeds the percolation threshold. Furthermore, the optimized nanocomposite AEM has higher ionic conductivity than the control AEM with similar ion-exchange capacity due to the well-developed morphology.

In this paper, three organic intercalating agents containing cations [hexadecyl trimethyl ammonium bromide (CTAB), poly(acrylamide-co-diallyldimethylammonium chloride), and quaternized polyethyleneimine] are used to prepare intercalated montmorillonites (MMT) by ion-exchange method. Then the modified MMTs are doped with vinylbenzyl chloride and styrene copolymer [poly(vinylbenzyl chloride-co-styrene)] for fabricating composite anion-exchange membranes (AEM). Fourier transform infrared, X-raydiffraction, thermogravimetric analysis, scanning electron microscopy, and Mastersizer laser particle size analyzer are employed to characterize the structure and morphology of MMTs and AEMs. The successful intercalation of MMTs is approved, and the MMT intercalated by CTAB shows an interlayer distance of 2.31 nm. The properties of the composite membranes including water uptake, mechanical property, and ionic conductivity are investigated. Among all the AEMs, the composite membrane containing MMT sheets with CTAB demonstrates better compositive performances. It presents an ionic conductivity of 2.09 × 10−2 S cm−1 at 80°C and good alkaline solution stability. Copyright © 2016 John Wiley & Sons, Ltd.

Near infrared photoluminescent porous silicon nanocrystals(ncSi)-polyhedral oligomeric silsesquioxanes (POSS) polymer composites are synthesized using a combination of thermal hydrosilylation and polymerization between Vinyl-POSS and hydrogen-terminated silicon nanocrystals (ncSi:H). The synthesized materials are characterized by IR, powder X-ray diffraction and solid-state nuclear magnetic resonance (NMR) (13C and 29Si). The results demonstrate that the hydrosilylation–polymerization reaction proceeded to create chemically crosslinked Vinyl-POSS-ncSi composites in which the integrity of the POSS cages is maintained intact. Scanning electron microscope (SEM) results demonstrate that morphology of these materials depends on the weight ratio of ncSi:H to Vinyl-POSS. Brunauer–Emmett–Teller surface area analyses establish that the composites have high surface areas ranging from 290.5 to 1047.2 m2 g−1 and pore volumes from 0.64 to 1.17 cm3 g−1. The pore sizes range from 6.08 to 3.54 nm and are dependent on the weight ratio of Vinyl-POSS to ncSi:H. Photoluminescence spectroscopy shows that the absolute quantum yield of the nanocomposites is not affected by the weight ratio of ncSi:H to Vinyl-POSS. Thermal gravimetric analysis results show that the POSS polymer composites with ncSi have lower thermal stability in nitrogen atmosphere as compared with the pure Vinyl-POSS polymer. It is envisioned that future applications for these composites will likely be found in the fields of advanced materials, gas adsorption media, and biomedicine.

A series of novel polydimethylsiloxane (PDMS) composites were prepared using octa[(trimethoxysilyl)ethyl]-POSS (OPS) as cross-linker and fumed silica as reinforcing filler. The cross-linked networks, morphologies, thermal and mechanical properties of these novel PDMS composites were examined by attenuated total reflection infrared spectroscopy and the extraction/swelling experiment, scanning electron microscope, thermogravimetric analysis, and universal tensile testing machine, respectively. It was found that both the resistance to thermal degradation and mechanical properties of the novel PDMS composites were improved greatly by adding fumed silica. The prominent improvements in resistance to thermal degradation and mechanical properties of novel PDMS composites were likely attributed to the enhanced interaction of PDMS chains and aggregated particles resulted from synergistic effect between POSS and fumed silica. Meanwhile, we also found that the resistance to thermal degradation of the PDMS composites was lowered slightly with the further increment in loading fumed silica, but their mechanical properties were enhanced. The slight decrease in trend of the resistance to thermal degradation of the novel PDMS composites was likely ascribed to the increasing amount of hydroxyl groups resulting from fumed silica. And the improving mechanical properties were mainly attributed to the increasing interaction of PDMS chains and aggregated particles originated from synergistic effect between POSS and fumed silica. POLYM. COMPOS., 34:1041–1050, 2013. © 2013 Society of Plastics Engineers

It is a challenge to synthesize transparent polydimethylsiloxane (PDMS) materials that can completely absorb the light energy of ultraviolet (UV) A, B, and C regions. Herein, near-infrared (NIR) photoluminescent PDMS composites with hydrogen-terminated silicon nanocrystals (ncSi:H) or decyl-terminated silicon nanocrystals (ncSi-decyl) fabricated by combination of hydrosilylation and polymer encapsulation are reported. Their morphologies, optical and mechanical properties, and thermal stabilities are investigated. It is interesting to find that these PDMS composites filled with even a very small amount of ncSi:H or ncSi-decyl have unprecedented UV-blocking properties and superior thermal stabilities as compared to the PDMS reference. In particular, the ncSi-decyl/PDMS composite possesses impressive photoluminescence. Furthermore, ncSi-decyl are favorable for reinforcing the mechanical properties of the PDMS composites as compared to the PDMS reference and the ncSi:H/PDMS composite. The enhancement in the mechanical properties and thermal stabilities of these novel PL PDMS composites depends upon the creation of crosslinkable sites and entanglement interactions between the PDMS chains and the ncSi. These results suggest that potential applications for NIR photoluminescent ncSi/PDMS composites will likely be found in the fields of advanced UV-blocking textiles, cosmetics, photofluids, stretchable electronic devices, anticounterfeiting materials, biological imaging, and diagnostics.