Effects of Bulky Copolymers on Ion Transport in an Anhydrous Proton-Conducting Electrolyte

Anhydrous proton-conducting electrolytes composed of a mixture of MePEG(7)SO(3)H [where PEG is poly(ethylene glycol)] acid and a sol-gel-based MePEG(3) copolymer were prepared. These copolymers were prepared by mixing the MePEG(3)(CH2)(3)Si(OCH2CH3)(3) monomer and different bulky comonomers: phenyltriethoxysilane, diphenyldimethoxysilane, and isobutyltrimethoxysilane. The MePEG(3) copolymers showed smaller volume fractions of PEG and nearly the same fractional free volume as the parent MePEG(3) polymer. End-group analysis showed that the incorporation of bulky group decreased the degree of condensation in the sol-gel polymer. This loss of condensation lead to an increase in the fluidity of the MePEG(3) copolymers, which in turn resulted in larger ionic conductivities in the copolymers compared with the parent MePEG(3) polymer. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3478569] All rights reserved.