Preparation and properties of poly(imide siloxane) segmented copolymer/silica hybrid nanocomposites

A series of Poly(imide siloxane) (PIS)/silica (SiO 2 ) hybrid nanocomposites with C‐Si covalent bonding between the homogeneous PIS copolymer and SiO 2 have been successfully synthesized. The PIS copolymer synthesized in this study is characterized by the coexistence of two segments: the polyimide segment and polydimethyldiphenylsiloxane segment, and the latter are specially featured with the introduction of a diphenyl group for improved homogeneity. The PIS/SiO 2 hybrid nanocomposites were prepared from 3,3′,4,4′‐bezonphenone tetracarboxylic dianhydride (BTDA), 2‐2′‐bis[4(3‐aminophenoxy)phenyl] sulfone ( m ‐BAPS), and vinyl‐containing α,ω‐bis‐(aminopropyl)polydimethyldiphenyl siloxane (APPPVS) oligomer to form vinyl siloxane‐containing poly(amic acid) (PAAVS). This copolymer was further reacted with trimethoxyvinylsilane (TMVS), 2,2′‐azobis‐isobutyronitrile (AIBN), and tetraethoxysilane (TEOS). The PIS/SiO 2 hybrid nanocomposites exhibited a series of properties unlike traditional composites, and the nano sized inorganic particles have resulted in a transparent hybrid when the SiO 2 content was less than 12 wt %. The Young's modulus and tensile strength of the PIS/SiO 2 hybrid nanocomposites increased with increasing SiO 2 content, whereas, the elongation at break was only slightly affected. The structure of the hybrids was characterized by FTIR, 29 Si‐NMR, 1 H‐NMR, and 13 C‐NMR, as well as SEM and TEM. The thermal properties of the PIS/SiO 2 hybrid nanocomposites were investigated with DSC, TGA, and DMA studies. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007