Polydimethylsiloxane/silica/titania composites prepared by solvent-free sol-gel technique

Composites based on polydimethylsiloxane incorporating silica and titania were prepared by mixing polydimethylsiloxane with proper oxides precursors, tetraethyl-orthosilicate and tetrabutyl-orthotitanate. In the presence of environmental humidity and in acid catalysis, hydrolysis/condensation processes take place with formation of oxides and concomitantly polymer crosslinking. Partial replacement of SiO(2) in a polydimethylsiloxane/silica composite with titania (both generated in situ by sol-gel process) affects surface hydrophilicity (evaluated by dynamic contact angle), water vapor sorption ability (determined by dynamic vapor sorption) and thermal stability. The dielectric properties are also controlled by composition.