Improved mechanical strength of partially sulfonated polystyrene-poly (dimethylsiloxane) block copolymer proton exchange membranes by nanoscale sequestration of thermally crosslinked silicone

Direct sulfonation and photocrosslinking of unsaturated poly(styrene-b-butadiene-b-styrene) for proton exchange membrane of direct methanol fuel cell

“…In the previous studies the BCP ionomers usually showed a percolation behavior in the plot of proton conductivity vs. DS due to the formation of proton conducting channels by fusion of ion clusters [18,19]. Fig.…”

“…Second, the crosslinking keeps the PEMs from effective hydration and subsequent swelling, which actually helps the formation of proton conducting channels. In developing crosslinked PEM, one should consider trade-off characteristics between proton conductivity and chemical stability [18]. Crosslinking usually improves the chemical and mechanical stability (and fuel crossover) of the membrane, while sacrificing the proton conductivity.…”

“…Well-controlled formation of proton conducting channels in BCP have shown promising PEM properties for DMFC. In BCP PEM, sulfonated PS serves as hydrophilic domains and hydrophobic rubbery blocks such as polyisobutylene (PI) [2,16], poly(ethylene-ran-butylene) [17], polybutadiene (PB) [23], or poly(dimethylsiloxane) (PDMS) [18,19] provide processibility for the membrane casting as well as efficient formation of proton channels. From the manufacturing standpoint, SBS is a good candidate for BCP PEM due to a relatively low price ($$1.50/lb) and a large production (410Mtons/year) worldwide [24].…”

“…One approach is to utilize the sulfonated form of the nonperfluorinated, but chemically stable polymers such as polystyrene (PS), [7] poly(ether ether ketone) (PEEK), [8,9] polyimide, [10] poly(phenyleneoxide), [11] poly(ether sulfone) (PES) [12][13][14][15]. Another fascinating idea to reduce methanol crossover through PEM is to utilize the nanostructured morphology of the block copolymer (BCP) generated by thermodynamically induced microphase separation [2,[16][17][18][19][20]. By cautiously controlling BCP microphase separation, Park et al achieved the different ion conductivities along different direction (through-plane vs. inplane) of BCP orientation [21,22].…”

Synthesis and properties of an anion-exchange membrane based on vinylbenzyl chloride–styrene–ethyl methacrylate copolymers

“…The samples were then dried in a vacuum oven at 50 1C for more than 2 days. The water uptake was calculated using the following equation [32]:…”