Tailored synthesis and fundamental characterization of organic-inorganic hybrid gels by means of a hydrosilylation reaction

Organic-inorganic hybrid gels have been synthesized from siloxane, 1.3,5,7-tetramethylcyclotetrasiloxane (TMCTS), tetrakis(dimethylsilyloxy)silane (TDSS) or silsesquioxane, 1,3.5,7.9,11,13,15-octakis(dimethylsilyloxy)pentacyclo-[9,5,1,1,1,1]octasilsesquioxane (POSS), as cross-linking reagents and alpha,omega-nonconjugated dienes, 1,5-hexadiene (HD), 1.7-octadiene (OD) and 1,9-decadiene (DD), using a hydrosilylation reaction with a Pt catalyst. The network structures of the resulting gels were investigated by means of a novel scanning microscopic light scattering system. The structures of the crosslinking reagent and the length of the alpha,omega-non-conjugated dienes strongly affected the formation and network structures of the resulting gels. The critical gel concentration decreased when the molecular length of the non-conjugated diene used was increased. The structures and Si-H group numbers of the crosslinking reagents affected the critical gel concentration, and its values decreased in the following order: TDSS > TMCTS > POSS. The mesh size distribution in the network structure was quantitatively characterized using the light scattering system and almost presupposed sizes with quite narrow size distributions were attained in the gels from TMCTS-HD, OD systems and TDSS-OD systems. On the other hand, the gels derived from POSS or DD showed larger mesh sizes than expected.