In situ formation of nanosized TiO2 domains within poly(amide-imide) by a sol-gel process

Poly(amide-imide)/TiO2 (PAVTiO(2)) composite films were prepared by an in situ sol-gel process. These composite films exhibited high optical transparency, having nanosized TiO2 rich domains well dispersed within the PAI matrix. The size of the domains increased from 5 to 50 nm when the TiO2 content was increased from 3.7 to 17.9% by weight. Hydrogen bonding interactions between the amide groups in the PAI and the hydroxyl groups on the inorganic oxide were observed. In comparison to the pure PAI polymer, the PAI/TiO2 composite films exhibited higher glass transition temperature, an increase and flattening of the rubbery plateau modulus, and a decrease in crystallinity. (C) 1999 Elsevier Science Ltd. All rights reserved.