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

Some polyimide films based an cyclobutane-1,2,3,4-tetracarboxylic dianhydri de (CBDA) and aromatic diamines were synthesized to investigate their tempe rature resistance and percent transmission of Light. The preparations of CB DA were investigated; they produced almost 10 times the yield of CBDA in co mparison to yields obtained by previous methods. The configuration of CBDA was determined by X-ray analysis to be cis-trans-cis. The polymer films sho wed excellent thermal resistance and were transparent and colorless, desira ble characteristics for practical applications in the field of polymer engi neering. However, the polymer obtained from a pyromellitic dianhydride inst ead of from CBDA was deep yellow and not desirable for high-qualified displ ay materials such as Liquid-crystal displays. The percent transmission of t he polymers obtained from CBDA and aromatic diamines ranged from 81.5 to 85 .8%, whereas the deep-yellow polymers showed low percent transmissions rang ing from 48 to 63.9%. (C) 2000 John Wiley & Sons, Inc.