Title

Perfluorinated-Ionomer-Membrane-Based Microcomposites: Silicon Oxide Filled Membranes

Document Type

Article

Publication Date

7-21-1989

Department

Polymers and High Performance Materials

Abstract

The objective of this work was to affect the in situ growth of silicon oxide microclusters or interpenetrating networks in Nation membranes via the sol-gel reaction for tetraethoxysilane (TEOS). The underlying hypotheses are: 1) The resultant morphology of the inorganic phase is ordered by the polymer's phase-separated morphology. 2) TEOS/ alcohol/H2O solutions will preferentially incorporate within pre-existing polar clusters. 3) TEOS hydrolysis in clusters is catalyzed by the fixed SO3H groups. Reproducible procedures for the in situ growth of "silica" in hydrated membranes contacting TEOS/alcohol solutions were established. Solids uptake vs. immersion time curves are a function of alcohol solvent type. Tensile properties vs. solids uptake indicate an initial strengthening, followed by a ductile-brittle transition suggesting a silicon oxide phase percolation threshold. FT-IR and 29Si solid state NMR analyses of microstructural evolution portray an inorganic network that is not as highly crosslinked as that of sol-gel-derived free silica and in fact becomes less coordinated and connected with increasing solids uptake.

Publication Title

ACS Symposium Series

Volume

395

First Page

401

Last Page

417

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