Amine Grafted Silica/SPEEK Nanocomposites as Proton Exchange Membranes

Sulfonated polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene/sulfonated poly(ether sulfone) and hexagonal boron nitride electrolyte membrane for fuel cell applications

Novel proton exchange membranes consisting of sulfonated polystyrene ethylene butylene polystyrene (sPSEBPS), sulfonated poly ether sulfone (SPES) and hexagonal boron nitride (hBN) were fabricated using a facile solution casting technique. The PSEBPS polymer was functionalized using chlorosulfonic acid as the sulfonating agent. Polymerization was typically conducted by taking three different monomers, namely 3,6-dihydroxy naphthalene-2,7-disulfonic acid disodium salt, 4,4'-dichlorodiphenyl sulfone, and bisphenol-A, to yield sulfonated poly ether sulfone (SPES). The resultant SPES polymer was blended with sPSEBPS followed by incorporation with an appropriate quantity of hBN. The physicochemical and structural properties of the membranes were studied in order to evaluate their compatibility with fuel cell applications. X-Ray photoelectron spectroscopy data validated the successful incorporation of the filler into the polymer matrix. Water absorption of the membranes was found in the range between 19.5 and 29.8%. The membrane loaded with 4.0 wt% of hBN showed the maximum ion-exchange capacity of 1.21 meq g^-1, whereas the control sPSEBPS/SPES membrane was restricted to 0.48 meq g^-1. The composite membrane loaded with hBN displayed higher thermal stability than that of the control sample. The sPSEBPS/SPES/hBN-4 composite membrane exhibited an ionic conductivity of 0.0329 S cm^-1 at 30 °C. Overall, the experimental data of the prepared composite membranes revealed that the materials are potential candidates for fuel cells.

Radiation Induced Surface Modification of Nanoparticles and their Dispersion in the Polymer Matrix

Polymer grafted inorganic nanoparticles attract significant attention, but pose challenges because of the complexity. In this work, a facile strategy to the graft polymer onto the surface of nanoparticles have been introduced. The vinyl functionalized SiO2 nanoparticles (NPs) were first prepared by the surface modification of the unmodified SiO2 using γ-methacryloxy propyl-trimethoxylsilane. The NPs were then mixed with polyvinylidene fluoride (PVDF), which was followed by the Co-60 Gamma radiation at room temperature. PVDF molecular chains were chemically grafted onto the surface of SiO2 nanoparticles by the linking of the double bond on the NPs. The graft ratio of PVDF on SiO2 NPs surface can be precisely controlled by adjusting the absorbed dose and reactant feed ratio (maximum graft ratio was 31.3 wt%). The strategy is simple and it should be applied to the surface modification of many other nanoparticles. The prepared PVDF-grafted SiO2 NPs were then dispersed in the PVDF matrix to make the nanocomposites. It was found that the modified NPs can be precisely dispersed into the PVDF matrix, as compared with pristine silica. The filling content of modifications SiO2 NPs on the PVDF nanocomposites is almost doubled than the pristine SiO2 counterpart. Accordingly, the mechanical property of the nanocomposites is significantly improved.

Enhancing the performance of SPEEK polymer electrolyte membranes using functionalized TiO2 nanoparticles with proton hopping sites

In this work, the application of a sulfonated poly(ether ether ketone) (SPEEK)/amine functionalized titanium dioxide nanoparticle (AFT) composite as a novel membrane in proton exchange membrane fuel cells (PEMFC) was studied.

Surface modification of Fe2TiO5 nanoparticles by silane coupling agent: Synthesis and application in proton exchange composite membranes

Modifying surfaces of nanoparticles with silane coupling agent provides a simple method to alter their surface properties and improve their dispersibility in organic solvents and polymer matrix. Fe2TiO5 nanoparticles (IT) were modified with 3-aminopropyltriethoxysilane (APTES) as novel reinforcing filler for proton exchange membranes. The main operating parameters such as reaction time (R.T), APTES/IT and triethylamine (TEA)/IT ratios have been optimized for maximum grafting efficiency. The optimum conditions for R.T, APTES/IT and TEA/IT ratios were 6h, 4 and 0.3 respectively. It was observed that the APTES/IT and TEA/IT ratios were the most significant parameters affecting the grafting percentage. Modified nanoparticles were characterized using FT-IR, TGA, SEM, TEM and XRD techniques. Effects of modified nanoparticles in proton exchange membrane fuel cells (PEMFC) were evaluated. The resulting nanocomposite membranes exhibited higher proton conductivity in comparison with pristine SPPEK and SPPEK/IT membranes. This increase is attributed to connectivity of the water channels which creates more direct pathways for proton transport. Composite membrane with 3% AIT (6.46% grafting amount) showed 0.024 S cm(-1) proton conductivity at 25 °C and 149 mW cm(-2) power density (at 0.5V) at 80 °C which were about 243% and 51%, respectively higher than that of pure SPPEK.

Amino-functionalized mesoporous silica based polyethersulfone–polyvinylpyrrolidone composite membranes for elevated temperature proton exchange membrane fuel cells

It is important to find alternative membranes to the state-of-the-art polybenzimidazole based high temperature proton exchange membranes with high proton conductivity at elevated temperature but with simple synthesis procedures.