INFRARED INVESTIGATION OF THE SILICON-OXIDE PHASE IN [PERFLUORO-CARBOXYLATE SULFONATE (BILAYER)]/[SILICON OXIDE] NANOCOMPOSITE MEMBRANES/

[Perfluoro-organic]/[silicon oxide] hybrids were formed by conducting sol-gel reactions of tetraethylorthosilicate within a perfluoro(carbox ylate/sulfonate) bilayer membrane in the Co+2 form. FTIR and Si-29 sol id-state NMR spectroscopies were used to probe general aspects of mole cular structure within the silicon oxide phase as a function of its re lative content. The internal gel structure is considerably unconnected in terms of the population of Si-O-Si groups in cyclic vs. linear sub structures and degree of Si atom coordination about bonded SiO4 units. In situ (HO)(x)SiO2[1-1/4x] intrastructure become increasingly less c onnected and more strained with regard to bonding geometry with increa sing percent silicon oxide. Structural differences are seen between th e silicon oxide component incorporated in carboxylate and sulfonate la yers. These inorganically modified perfluorinated ionomers have potent ial as fast-proton conducting membranes for fuel cells and as permsele ctive membranes in liquid pervaporation cells. (C) 1998 John Wiley & S ons, Inc.