Preparation and characteristics of poly(amide–imide)/titania nanocomposite thin films

Abstract

Poly(amide–imide)/titania (PAI/TiO 2) nanocomposite has been successfully fabricated through the in situ formation of TiO 2 within a PAI matrix by sol-gel process. Poly(amide amic acid) solutions are prepared by mixing 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (p-BAPP), trimellitic anhydride chloride (TMAC) and N, N-dimethyl formamide (DMF) solvent. Tetraethyl orthotitanate (Ti(OEt) 4) and actylacetone (ACAC), the latter one is used as chelating agent, are then added to the poly(amide amic acid). Through the sol-gel process and imidization reaction, the PAI/TiO 2 nanocomposite films are formed. In this study, the addition of TMAC to the PAI/TiO 2 nanocomposite films is employed to provide the intermolecular hydrogen bonded between the PAI and PAI or titania. The TiO 2 particle sizes of PAI/TiO 2 (TiO 2 is 8.12 wt. %) are between 40 and 90 nm by the transmission electron microscope (TEM) measurement. Based on X-ray photoelectron spectroscopic (XPS) analysis, the TiO 2 content on the surface of PAI/TiO 2 is higher than that of pure polyimide/titania (PI/TiO 2) nanocomposite film. Thermal decomposition temperatures ( T d), at 5 wt.% loss, are above 460 °C of PAI/TiO 2 and PI/TiO 2 nanocomposite films. The dynamic mechanical analysis (DMA) of the PAI/TiO 2 and PI/TiO 2 nanocomposite films with higher TiO 2 content possesses superior mechanical properties and glass transition temperatures.