Electrochemical impedance studies of hybrids of perfluorosulfonic acid ionomer and silicon oxide by sol-gel reaction from solution

Abstract

Hybrids of Nafion® and silica were prepared from solution, growing the inorganic phase by hydrolysis/condensation of alkoxy silanes. Using tetraethoxysilane (TEOS) as the inorganic precursor, transparent and rigid films were obtained. Substituting part of the TEOS (20 wt% substitution) by 1,1,3,3 tetramethyl-1,3-diethoxydisiloxane (TMDES) more flexible films were obtained. These films were translucent and showed a phase segregation which was clearly observed by transmission electron microscopy. The ionic conductivity of the hybrids was measured by electrochemical impedance spectroscopy using two stainless steel electrodes, a frequency range of 0.1 to 105 Hz, and temperatures from 25 to 100°C. Samples were also characterized by modulated differential scanning calorimetry. © 1998 Elsevier Science S.A. All rights reserved.