Preparation and properties of aromatic polyimides based on 4,4?-(2,2,2-trifluoro-1-phenylethylidene)diphthalic anhydride

Abstract

Aromatic polyimides were synthesized from aromatic carboxylic acid dianhydrides, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 4,4′-(2,2,2-trifluoro-1-phenylethylidene)diphthalic anhydride (3FDA), and pyromellitic dianhydride (PMDA), with four typical aromatic diamines. These included polyimide (PI) from 2,2-bis(4-aminophenyl)hexafluoropropane (4BDAP) by two-step procedures; amidation to polyamic acid (PAA), followed by thermal imidization of PAA. The chemical and physical properties of the newly prepared polyimides were compared in terms of their chemical structures, inherent viscosity, thermal property, transmission, dielectric constant, UV cutoff, water absorption, and refractive index. PIs 3FDA/4BDAP and 6FDA/4BDAP were soluble in common organic solvents, whereas others were not. In particular, it was found that the solubility was dependent on the temperature of imidization. The chemical and physical properties of the newly prepared polyimides derived from 3FDA were similar to the polyimides derived from 6FDA. The solubility of polyimide containing an ether functional group in the dianhydride moiety was better than that of the ether functional group in the diamine moiety. The polymers with ether linkage in dianhydride moiety exhibited lower glass transition temperature than their functionality-reversed analogous polymers with ether linkage in diamine moiety. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 38–44, 2002