Synthesis, Characterization and Dynamic Mechanical Properties of Polyimide-Polyurea-Polysilsesquioxane Block Terpolymers

Abstract

A novel type of polyurea-b-polyimide(PUI)-LPS terpolymer containing ladder like polysilsesquioxane (LPS) hybrid thin film was successfully prepared by coupling ladder-like polysilsesquioxane (LPS) with polyurea-b-poly(amide acid), followed solution film casting and thermal imidization. The LPS composed of mercapto and fluoride side groups was synthesized by sol–gel and monomer self-assembly methods. The structure and properties of the resulting PUI-LPS thin films were affected by the reaction conditions. Dynamic contact angles (DCA) and dynamic mechanical analysis (DMA) were used to study the surface energy and mechanical properties of PUI-LPS thin films. The presence of LPS containing fluoride and mercapto side groups significantly increased the extent of cyclodehydration (imidization) process at a relatively low temperature of about 150°C. The surface energy of the hybrid thin films was remarkably decreased as LPS concentration increased. The dynamic mechanical properties of the hybrid thin films were determined by dynamic mechanical analysis (DMA). Fourier transform infrared spectroscopy (FTIR) and Wide-angle X-ray diffraction (WAXRD) methods were used to study the composition and structure of the hybrid thin films