Preparation and characterization of poly(imide siloxane) (PIS)/titania(TiO 2) hybrid nanocomposites by sol–gel processes

Abstract

Poly(imide siloxane)(PIS)/titania(TiO 2) hybrid nanocomposites with organic–inorganic covalent bonding have been successfully synthesized by sol–gel processes. The PIS copolymer synthesized in this study was characterized by the observed coexisting two segments: the polyimide (PI) segment and polydimethyldiphenylsiloxane segment, and the latter were specially featured with the introduction of a diphenyl group for improved homogeneity. The obtained TiO 2 networks in PIS matrix were well dispersed and their average diameter was less than 50 nm. Meanwhile, the PIS/TiO 2 hybrid nanocomposite films exhibited good optical transparency at 20 wt% of TiO 2 content. The thermal stability, tensile strength and elongation of the nanocomposites decreased with increasing TiO 2 content. The glass transition temperature ( T g) and Young’s modulus increased with increasing TiO 2 content. The chemical structure and morphologies of PIS/TiO 2 hybrid nanocomposites was characterized by Fourier transform infrared spectroscope (FT-IR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscope (TEM). The T g and thermal stability were measured by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), respectively. The mechanical properties were examined by dynamic mechanical analysis (DMA) under controlled force mode.