Preparation of Polyimide-TiO₂ Hybrid Films by Synthesis of Polyamic Acid Having Carboxylic Acid Group Sidechains in the Presence of TiO₂

Abstract

Polyimide-TiO2 hybrid films, PICOOH-TiO2s, were prepared by the synthesis of polyamic acid having carboxylic acid group sidechains in the presence of TiO2. TiO2 and benzophenonetetracarboxylic dianhydride (BTDA) were added to a solution of 3,5diaminobenzoic acid and 4,4'-oxydianiline(ODA) in NMP and stirred at room temperature for 24 h, 220 h, and 410 h. The NMP solutions were cast onto a glass plate and dried at 70 o C, and thermal cyclodehydration of the polyamic acid was performed by successive heating at 100 o C for 1 h, 200 o C for 1 h, and 300 o C for 1 h. Tg values of polyimides in the polyimide-TiO2 hybrid films, PICOOH-TiO2-24, prepared by stirring for 24 h after the addition of TiO2 and BTDA, PICOOH-TiO2-220 prepared by stirring for 220 h, and PICOOH-TiO2-410 prepared by stirring for 410 h, were 284 o C, 361 o C, and 377 o C, respectively. The Tg values became higher with increased stirring time after the addition of TiO2 and BTDA, exhibiting stirring time dependence.