The synthesis and X-ray structure of 1,2,3,4-cyclobutane tetracarboxylic dianhydride and the preparation of a new type of polyimide showing excellent transparency and heat resistance

Some polyimide films based an cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA) and aromatic diamines were synthesized to investigate their temperature resistance and percent transmission of Light. The preparations of CBDA were investigated; they produced almost 10 times the yield of CBDA in comparison to yields obtained by previous methods. The configuration of CBDA was determined by X-ray analysis to be cis-trans-cis. The polymer films showed excellent thermal resistance and were transparent and colorless, desirable characteristics for practical applications in the field of polymer engineering. However, the polymer obtained from a pyromellitic dianhydride instead of from CBDA was deep yellow and not desirable for high-qualified display materials such as Liquid-crystal displays. The percent transmission of the polymers obtained from CBDA and aromatic diamines ranged from 81.5 to 85.8%, whereas the deep-yellow polymers showed low percent transmissions ranging from 48 to 63.9%. (C) 2000 John Wiley & Sons, Inc.