Synthesis and Characterization of Sulfonated Polyphosphazene-graft-Polystyrene Copolymers for Proton Exchange Membranes  

作　　者：Min-lan He Hu-lin Xu Yan Dong Jia-hong Xiao Peng Liu Feng-yan Fu Saghir Hussain Shu-zhen Zhang Chao-jun Jing Qun Yu 朱长进 

机构地区：[1]Department of Applied Chemistry,Beijing Institute of Technology [2]Beijing Qintian Science & Technology Development Co., Ltd [3]Beijing Institute of Transfusion Medicine

出　　处：《Chinese Journal of Polymer Science》2014年第2期151-162,共12页高分子科学（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(No.51103012)

摘　　要：A novel series of polyphosphazene-grafl-polystyrene （PP-g-PS） copolymers were successfully prepared by atom transfer radical polymerization （ATRP） of styrene monomers and brominated poly（bis（4-methylphenoxy）phosphazene） macroinitiator. The graft density and the graft length could be regulated by changing the bromination degree of the macroinitiator and the ATRP reaction time, respectively. The PP-g-PS copolymers readily underwent a regioselective sulfonation reaction, which occurred preferentially at the polystyrene sites, producing the sulfonated PP-g-PS copolymers with a range of ion exchange capacities. The resulting sulfonated PP-g-PS membranes prepared by solution casting showed high water uptake, low water swelling and considerable proton conductivity. They also exhibited good oxidative stability and high resistance to methanol crossover. Morphological studies of the membranes by transmission electron microscopy showed clear nanophase-separated structures resulted from hydrophobic polyphosphazene backbone and hydrophilic polystyrene sulfonic acid segments, indicating the formation of proton transferring tunnels. Therefore, these sulfonated copolymers may be candidate materials for proton exchange membranes in direct methanol fuel cell （DMFC） applications.A novel series of polyphosphazene-grafl-polystyrene （PP-g-PS） copolymers were successfully prepared by atom transfer radical polymerization （ATRP） of styrene monomers and brominated poly（bis（4-methylphenoxy）phosphazene） macroinitiator. The graft density and the graft length could be regulated by changing the bromination degree of the macroinitiator and the ATRP reaction time, respectively. The PP-g-PS copolymers readily underwent a regioselective sulfonation reaction, which occurred preferentially at the polystyrene sites, producing the sulfonated PP-g-PS copolymers with a range of ion exchange capacities. The resulting sulfonated PP-g-PS membranes prepared by solution casting showed high water uptake, low water swelling and considerable proton conductivity. They also exhibited good oxidative stability and high resistance to methanol crossover. Morphological studies of the membranes by transmission electron microscopy showed clear nanophase-separated structures resulted from hydrophobic polyphosphazene backbone and hydrophilic polystyrene sulfonic acid segments, indicating the formation of proton transferring tunnels. Therefore, these sulfonated copolymers may be candidate materials for proton exchange membranes in direct methanol fuel cell （DMFC） applications.

关 键 词：Atom transfer radical polymerization Direct methanol fuel cell Graft copolymers Proton exchange membrane Polyphosphazenes. 

分 类 号：TM911.4[电气工程—电力电子与电力传动]