Neat and silica-enriched polysilsesquioxanes in dispersed media

The synthesis and characterization of organic-inorganic hybrid materials de rived from. 3-glycidoxypropyl trimethoxy silane (GPMS) is described. The hy drolytic condensation of GPMS was performed in two steps. The first one was carried out using tetrahydrofuran (THF) as solvent and diluted formic acid as catalyst (24 h at 50 OC). The reaction product was then dissolved in di glycidylether of bisphenol A (DGEBA) and the formation of the inorganic pol ymer was continued using different thermal cycles. A polysilsesquioxane (SS QO) dispersed in a reactive solvent was obtained. Its characterization by s ize exclusion chromatography (SEC) showed the presence of a broad distribut ion of clusters where the fundamental units were associated with cube-like cages. The organic polymer network was formed by adding methyltetrahydropht halic anhydride (MTHPA) as hardener and benzyl dimethylamine (BDMA) as init iator of the chainwise polymerization (involving the epoxy groups of the SS QO and those of DGEBA). A SSQO-modified epoxy network was obtained. A signi ficant increase in the abrasion resistance of the hybrid material with resp ect to the neat epoxy was observed. Silica-enriched SSQO were obtained by a dding tetraorthosilicate (TEOS) together with GPMS in the initial hydrolyti c tetraorthosilicate condensation step.