Preparation and Properties of Porous Polyimide Films Prepared from a Polymer Blends of Polyol and Poly(amide acid)

摘要

Porous polyimide films were prepared by thermally treating a polymer blend film of polyol and poly(amide acid) obtained from pyromellitic dianhydride (PMDA) and oxydianiline (ODA). Upon thermal treatment of the films at 300 to 400 t , the thermally less stable polyol domains decomposed, leaving porous polyimide films. The presence of pores was confirmed from the scanning electron microscope (SEM) of the surface and the cross-section of the films. The size distribution of the pore was narrow. With the increase of polyol content, the average pore size increased from 2-3 ~m to 6-7 ~m. The porous polyimide films had excellent physical properties in spite of the porous structure. Viscoelastic analyses showed that all the porous polyimide films had high glass transition temperature at above 400t, and storage moduli were maintained up to 400 t .Carbonization of the porous polyimide films at 900 t for I h gave porous carbon films maintaining the pore structure.