Study On Preparation And Properties Of Polyimide/SiO₂ Hybrid Films

At present, polymer/inorganic hybrids are in the frontier of polymer material sicence, and the polyimide(PI) hybrids are one of the recent hot fields. In this paper, PI/SiO₂ hybrid films were prepared by partly imidized copolyamic acid(PAA) via physical blending and in-situ sol-gel method respectively. The internal microstructure and properties of PI/SiO₂ hybrid films were studied.Firstly, during the synthesis process of partly imidized PAA, the effect factors such as the addition manner, materials ratio, reaction temperature, reaction time, solid content and the amount of cyclizing agents have great influence on the the intrinsic viscosity of partly imidized PAA. The successful synthesis of partly imidized PAA was confirmed by IR spectrum.Secondly, PI/SiO₂ hybrid films were successfully prepared by physical blending with different content of silane coupling agent KH-550. The microstructure and properties of hybrid films were investigated by means of IR,SEM,TGA,XRD,mechanical properties test. The results indicated that SiO₂ nanoparticles were dispersed well with the increase amount of KH550, and the thermally stability and mechanical properties of PI/SiO₂ hybrid films was better than those of pure PI.Thirdly, PI/SiO₂ hybrid films were also successfully prepared by in-situ sol-gel method with different wt% of SiO₂. Tetraethyl orthosilicate (TEOS) were added into partly imidized PAA without any water. The microstructure and properties of hybrid films were investigated. The results indicated that nanoparticles Si02 were also dispersed well in the matrix, with the increase of wt% of SiO₂, the thermally stability and mechanical properties of PI/SiO₂ hybrid films were better than pure PI . Compared to the PI/SiO₂ hybrid films obtained by physical blending, the ultimate properties of those obtained by in-situ sol-gel were increased.