Chapter 216 - A new process for the preparation of polyimide/silica hybrid films

Abstract

This chapter introduces a new process to prepare a series of transparent PI/silica hybrid films. The PI/silica hybrid films possess lower coefficient of thermal expansion, higher thermal stability, and better mechanical properties at room temperature compared with neat PI films. However, the mechanical properties of PI/SiO2 hybrid films by the traditional process decreased fast by the addition of SiO2 particles at higher silica content because of the fast increase of particle size; moreover, few studies have been carried out on cryogenic properties of the PI/SiO2 hybrid films. The mechanical properties at 77 K of the films prepared by the new process have been studied. The morphology of the films has been characterized by scanning electron microscopy (SEM) observation. It is shown that the newly developed sol-gel process led to smaller silica particle sizes than the traditional sol-gel process did. The PI/SiO2 hybrid films prepared by the new process show better cryogenic mechanical properties than the hybrid films prepared by the traditional sol-gel process.