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 SiO2 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.