| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 93 === A designed series of directly copolymerized homo- and disulfonated copolymers containing controlled degrees of pendant sulfonic acid groups have been synthesized via nucleophilic step polymerization. Novel sulfonated poly (arylene ether sulfone) copolymers using α-methylstilbene (HMS), with dichlorodiphenyl sulfone (DCDPS) and 3,3’-disodiumsulfonyl-4,4’-dichlorodiphenylsulfone (SDCDPS) were investigated. Molar ratios of DCDPS and SDCDPS were systematically varied to produce copolymers of controlled compositions, which contained up to 70 mol% of disulfonic acid moiety. The goal is to identify thermally, hydrolytically, and oxidatively stable high molecular weight,
film-forming, ductile ion conducting copolymers, which had properties desirable for proton exchange membranes (PEM) in fuel cells.
The sulfonated copolymers were prepared in the sodium-salt form and converted to the acid moiety and subsequently investigated as proton exchange membranes for fuel cells. Hydrophilicity increased with the level of disulfonation, as expected. Moreover, water sorption increased with increasing mole percent incorporation of SDCDPS. The copolymers’ water uptake depended on both bisphenol structure and degree of disulfonation. Furthermore, the acidification procedures were shown to influence the Tg, water uptake, and conductivity of the copolymers.
Proton conductivities for the sulfonated copolymers, under fully hydrated conditions, were a function of bisphenol structure and degree of sulfonation. A careful balance of copolymer composition and acidification method was necessary to afford films which can be both ductile and proton conductive. The copolymers of optimum design yielded conductivities of 0.1 S/cm or higher, which were comparable to those of commercial polyperfluorosulfonic acid films (Nafion™ ).
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