Enhanced conductivity in morphologically controlled proton exchange membranes: Synthesis of macromonomers by SFRP and their incorporation into graft polymers
Enhanced conductivity in morphologically controlled proton exchange membranes: Synthesis of macromonomers by SFRP and their incorporation into graft polymers
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DOI：
10.1021/ma010970m
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发表时间：
2002-02-12
期刊：
影响因子：
5.5
通讯作者：
Holdcroft, S
中科院分区：
文献类型：
--
作者：
Ding, JF;Chuy, C;Holdcroft, S
采用稳定自由基聚合(SFRP)和乳液聚合相结合的方法，合成了一系列由大单体聚苯乙烯磺酸钠(MacPSSNa)和聚苯乙烯(PS)主链接枝而成的新型接枝聚合物。用SFRP法制备了具有32个重复单元、多分散指数为1.25、结构清晰的PSSNa聚合物。用二乙烯基苯封端伪活性链，得到大分子单体(MacPSSNa)，再与苯乙烯乳液聚合，得到PS-g-MacPSSNa接枝聚合物。大单体接枝链的数密度由大单体与苯乙烯的投料比控制。采用模压成型和Na+离子交换质子的方法制备了质子交换膜。与无规共聚苯乙烯-苯磺酸(PS-r-PSSA)相比，接枝聚合物膜在特定的磺酸含量下表现出较低的吸水率和较大的质子电导率。透射电子显微镜显示，接枝聚合物膜具有较高的相分离程度和离子结构域间的连通性。
A novel series of graft polymers comprising graft chains of a macromonomer poly(sodium styrenesulfonate) (macPSSNa) and a polystyrene (PS) backbone have been prepared using a combination of stable free radical polymerization (SFRP) and emulsion polymerization. Well-defined PSSNa polymers possessing 32 repeat units and a polydispersity index of 1.25 were prepared by SFRP. The pseudo-living chains were terminated with divinylbenzene to afford a macromonomer (macPSSNa), which was subsequently copolymerized with styrene by emulsion polymerization to afford PS-g-macPSSNa graft polymers. The number density of macromonomer graft chains was controlled by the feed ratio of macromonomer to styrene. Films were prepared by compression molding and Na+ ions exchanged for protons to yield proton exchange membranes (PEMs). The graft polymer membranes exhibited lower water uptake but much larger proton conductivity for a given sulfonic acid content compared to membranes prepared from random copolymers of styrenesulfonic acid and styrene (PS-r-PSSA). Transmission electron microscopy showed that the graft polymer membranes exhibit a higher degree of phase separation and enhanced connectivity between ionic domains.