Title

Broadband Dielectric Spectroscopic Studies of Nafion®/Silicate Membranes

Document Type

Article

Publication Date

4-30-2010

Department

Polymers and High Performance Materials

Abstract

Nafion®/silicate nanocomposite membranes were prepared using in situ sol-gel reactions for tetraethylorthosilicate in pre-hydrated and methanol-swollen acid films. Chemical bonding in incorporated silicate nanostructures was characterized using ATR-FTIR and broadband dielectric (BDS) spectroscopies. BDS examined chain dynamics and approximate nature of charge hopping pathways. The behavior of the β relaxation on loss permittivity vs. frequency spectra was investigated. The peak maximum shifted only to somewhat higher frequencies with different silica percent indicating that the silicate component is confined to acid aggregates, not significantly perturbing the main chain. A parameter N obtained from fitting dielectric spectra to the Havriliak-Negami equation adjusted for d.c. conductivity, was used to characterize charge hopping pathways and charge mobility constraints. N showed a broad range suggesting morphological variation with silicate content and increased with temperature.

Publication Title

ACS Symposium Series

Volume

1040

First Page

113

Last Page

124

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