Preparation of colorless polyimide hybrid films with enhanced optical, chemical and thermal resistance

Abstract

In the present study, we prepared a polyimide hybrid film with improved transparency and chemical resistance by introducing cycloaliphatic epoxy-functionalized oligosiloxanes (CEOS) into polyimides. First, colorless polyamic acid (CPAA) was prepared from 4,4'-(hexafluoroisopropylidene) diphthalic anhydride and 3,3'-diaminodiphenyl sulfone, and then cross-linking and imidization reactions were carried out through the reaction between epoxy rings in CEOS and carboxylic acid groups in CPAA. The characteristics of polyimide hybrids were investigated by Fourier transform infrared, thermogravimetric analysis, scanning probe microscopy and scanning electron microscopy. The chemical resistance of the hybrid was examined by dropping an organic solvent on the surface of the hybrid film. The CEOS and CPAA hybrid of 1:2 molar ratio exhibited optimal chemical resistance and thermal stability. The surface roughness of the hybrid film showed very smooth morphology without any phase separation between CEOS and CPAA. The transparency of the film in visible light region was higher than original CPI films.

Keywords:

• transparent polyimide
• polyimide hybrid film
• colorless polyimide
• cross-linking
• phase separation

Acknowledgement

This work was supported by the BK21 plus program.