Synthesis of organic-inorganic hybrid gels from siloxane or silsesquioxane and α,ω-nonconjugated dienes by means of a photo hydrosilylation reaction

Organic-inorganic hybrid gels have been synthesized from the multifunctional cyclic siloxane, 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS), or the cubic silsesquioxane, 1,3,5,7,9,11,13,15-octakis(dimeth- ylsilyloxy)pentacyclo-[9,5,1,1,1,1]octasilsesquioxane (POSS), as cross-linking reagents with α,ω-nonconjugated dienes, 1,5-hexadiene (HD) or 1,9-decadiene (DD), using a photo hydrosilylation reaction with a bis(acetylac- etonato)platinum catalyst in toluene. Network structures of the resulting gels, mesh size, and mesh size distribution were quantitatively characterized by means of a novel scanning microscopic light scattering (SMILS). The effects of the monomer concentration in the resulting gels were investigated, and gels with homogeneous network structure formed by 1.4 to 1.6 nm size of mesh were obtained under the monomer concentrations that are relatively higher than the critical gelation concentration. The mesh sizes of gels, that were determined with SMILS, with DD were larger than those with HD and were independent of the nature of the cross-linking reagents. The TMCTS-HD gel formation process was successfully traced with SMILS. The result indicates the formation of microgels in the early stages of the reaction following aggregation of the microgels, extension of the microgels, or both to form the infinite network that occupies the space of the reaction system around the gelation point. Photo-pattern coating of a glass plate with the POSS-DD gel was achieved by means of the photo hydrosilylation reaction of the cast reaction medium.