Synthesis and characterization of novel coatable polyimide-silica nanocomposites

Abstract

We report synthesis of a novel diamine 1,2-bis(4-(Hydrazonomethyl)phenoxy)ethane (bis- HPE) and a derived novel polyimide. The diamine was reacted with PMDA and ODA to synthesize copolyimide. Unmodified and modified silica particles were dispersed in the polyimide to prepare polyimide-silica hybrids: (a) unmodified (PSH-UM), and (b) modified (PSH-M). The PSH-UM were prepared by generating silica particles in situ in PI. In PSH-M, structural group identical to PI, 2,6- bis(3-(triethoxysilyl)propyl)pyrrolo[3,4-f]isoindole-1,3,5,7(2H,6H)-tetraone was introduced into silica nano-particles. The structural similarity enhanced compatibility between organic-inorganic components by like-like chemical interactions as both contain flexible alkyl groups. PSH-M have shown improved surface smoothness, hydrophobicity and thermal stability. Such properties are mandatory for stable coatings. The structure of silica and PI was affirmed by FTIR, EDX, and solid-state 29Si NMR spectroscopy. Morphological and thermal properties of the prepared PI-SiO2 nano-composites were investigated by field emission scanning electron microscopy, atomic force microscopy, contact angle measurement and thermogravimetric analysis.