Synthesis and characterization of polyimides based on novel tricyclo[6,2,2,02,7] dianhydride

Abstract

3‐Phenyl‐tricyclo [6,2,2,02,7]dodeca‐2,11‐ene‐5,6,9,10‐tetracarboxylic dianhydride was prepared from 1,1‐diphenyl ethylene and maleic anhydride in 1 : 2 mole ratio by [4 + 2]π Diels‐Alder cycloaddition. The structure of the dianhydride was determined by mass spectroscopy, IR, 1H‐NMR, elemental analyses, and single crystal x‐ray diffraction. The monomer was condensed with several diamines in N‐methyl pyrrolidone or m‐cresol. The polyamic acids and the polyimides synthesized had inherent viscosities in the range of 0.19–0.31 and 0.17–0.25 dL/g, respectively, measured in N‐methyl pyrrolidone at 30°C. Both the polyamic acids and the polyimides were found to be soluble in m‐cresol, N‐methyl pyrrolidone, dimethylacetamide, dimethyl formamide, and dimethyl sulfoxide. The polymides showed a low degree of crystallinity from wide angle x‐ray diffraction. Thermal analysis of these polyimides revealed that their glass transition temperatures (Tg) were in the 215–237°C range and they decomposed in two stages. The first‐stage decomposition temperatures were almost the same in O2 or N2 atmospheres, but the polymers showed a better thermal stability in O2 rather than in N2 in the second stage. The mechanism of thermal degradation is discussed. Copyright © 1990 John Wiley & Sons, Inc.