Organic-inorganic hybrid networks

Abstract

Two types of organic-inorganic (O-I) networks with nanosized silica structures formed in situ by the sol-gel process were studied: (a) interpenetrating epoxy-silica networks and (b) hybrid networks with silica domains as crosslinks prepared from O-I precursors (alkoxysilyl end-capped polymers, organofunctional silsesquioxane clusters, functional microgels and polyhedral silsesquioxane “cages”). The effects of the type of the O-I precursor and interphase interaction on the formation, structure and mechanical properties of the hybrid network were determined. The formation of compact domain-like crosslinks from rigid precursors was shown to affect the critical behaviour in the system's gelation and resulted in a decrease in the dynamic critical exponent. Considerable reinforcement of the epoxide network by a small volume fraction of the in-situ formed silica was achieved. Dynamic mechanical analysis and comparison with bicontinuous theoretical models proved the co-continuous morphology of the hybrid silica-epoxy network.