Synthesis and characterization of sulfonated polyphosphazene-graft-polystyrene copolymers for proton exchange membranes

Autor: Chaojun Jing, Jia-hong Xiao, Minlan He, Fengyan Fu, Saghir Hussain, Yan Dong, Changjin Zhu, Peng Liu, Qun Yu, Hulin Xu, Shuzhen Zhang
Rok vydání: 2014
Předmět:
Zdroj: Chinese Journal of Polymer Science. 32:151-162
ISSN: 1439-6203
0256-7679
DOI: 10.1007/s10118-014-1394-0
Popis: A novel series of polyphosphazene-graft-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.
Databáze: OpenAIRE
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