SOL-GEL-XEROGEL EVOLUTION INVESTIGATED BY ELECTROACTIVE PROBES IN SILICA AND TRANSITION-METAL OXIDE BASED GELS

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.