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Electrochemical techniques, including chronoamperometry, have been used to explore the evolution of composition and structure of silica and transition-metal gels prepared by sol-gel processes. Electroactive probes have been either freely dissolved into the gels or attached to the polymeric and oligomeric species. Their diffusion kinetics have been analysed in relation to parameters such as the gelation catalyst, the gel aging and drying. The results confirm predictions made by other techniques and shed new light on the behaviour of such systems.

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Chronoamperometry has been performed on ferrocene embedded in silica and zirconia gels. The diffusion coefficient of ferrocene was measured along the sol-gel-xerogel transformations. Such electrochemical measurements are a sensitive probe of the structural and textural changes occurring in the sol-gel process.

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Class I hybrid poly(N-isopropylacrylamide)/silica hydrogels, PNIPAM/SiO2, were prepared by a new one shot synthesis. In this approach, the free-radical polymerization of vinyl groups of N-isopropylacrylamide (NIPAM) and the hydrolysis-condensation of alkoxy groups of tetramethoxysilane (TMOS) are performed concomitantly using sodium persulfate and 3-(dimethylamino)-propionitrile, a well-known couple to initiate the organic polymerization. The cross-linker is N,N-methylenebisacrylamide. The kinetic study of mechanical properties from the sol-to-gel state for different ratios of TMOS/NIPAM was investigated by rheological ultrasonic measurements. The thermoresponse of hybrid materials was investigated by differential scanning calorimetry and the measurements showed that hybrid gels present a lower critical solution temperature, which is similar with one of single organic hydrogel.