In this study, two series of poly(arylene ether sulfone)s (PAES) with hydrophobic blocks made of 4,4 0 -dihydroxyphenyl (BP) and 2,2-bis(4-hydroxyphenyl) propane (BPA) were synthesized. The copolymers were prepared by a coupling reaction between decafluorobiphenyl (DFBP) end-capped nonsulfonated block (PAES A or B) and sulfonated block (SPAES B). The reactive behavior of DFBP facilitates the low-temperature coupling reaction (below 105 C). The final copolymers were blended at distinct weight percent ratios (0, 20, 30, and 40) with poly(styrene-b-isobutylene-b-styrene) (SIBS) at a sulfonation level of 88% to obtain strong and flexible membranes. Morphological, thermal stability, and conduction properties of the resulting membranes were measured and reported here. Results suggest that phase segregation between hydrophobic and hydrophilic domains occurs below 1 meq. g À1 ion exchange capacity. These membranes have low water absorption and high thermal stability. Incorporating SIBS 88 into the blend added elastomeric behavior enhancing transport properties and additional ionic domains, achieving proton conductivities of 0.21 S cm À1 for BPA-based membranes at 50 C (40% SIBS 88). The selectivity of the studied membranes surpasses Nafion ® 117, making them strong candidates for proton exchange membranes in direct methanol fuel cell applications.
This study discusses the synthesis of sulfonated amine block copolymers and the effect of multiple ionic domains and counter-ion substitution on polymeric membranes' morphology and transport properties for chemical protective clothing (CPC) applications. The monomers 2-(tert-butylamino) ethyl methacrylate, 2-ethoxy ethyl methacrylate, and styrene were used to prepare the block copolymers by atom transfer radical polymerization (ATRP). The copolymers were then sulfonated by chemical grafting with pendants sulfobutyl groups onto the polymer structure. Properties of the resulting membranes were evaluated as a function of block composition, incorporation of sulfonic groups, and counter-ion substitution. Blended membranes with sulfonated poly(styreneisobutylene-styrene) (SIBS) were also studied. A series of materials characterization techniques (e.g., Fourier-transform infrared spectroscopy [FT-IR], thermogravimetric analysis [TGA], atomic force microscopy [AFM], Smallangle X-ray scattering [SAXS]/wide-angle X-ray scattering [WAXS]) were performed to describe the changes to the membranes. The results indicate that synthesized copolymers lack phase segregation mainly because of a low sulfonation on the central amine block, leading the material to have a low Water/ DMMP selectivity. As the sulfonated copolymers were blended with SIBS 75, the breathability of the membranes were enhanced 1.5 times, and almost all candidates achieved the water vapor transport rate limit of 1500 g m À2 day À1 . Finally, the better-found candidates for DMMP CPC were Mg 2+ membranes, achieving selectivity between 20 and 90 range.
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