Preparation and characterization of poly(imide siloxane) (PIS)/titania(TiO2) hybrid nanocomposites by sol–gel processes

Poly(imide siloxane)(PIS)/titania(TiO2) 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 TiO2 networks in PIS matrix were well dispersed and their average diameter was less than 50 nm. Meanwhile, the PIS/TiO2 hybrid nanocomposite films exhibited good optical transparency at 20 wt% of TiO2 content. The thermal stability, tensile strength and elongation of the nanocomposites decreased with increasing TiO2 content. The glass transition temperature (Tg) and Young’s modulus increased with increasing TiO2 content. The chemical structure and morphologies of PIS/TiO2 hybrid nanocomposites was characterized by Fourier transform infrared spectroscope (FT-IR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscope (TEM). The Tg 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.