Organosoluble optically transparent poly(amide-imide)s based on 2,2-bis [N-(3-carboxyphenyl)phthalimidyl]- hexafluoropropane and 2,2-bis [N-(4-carboxyphenyl)phthalimidyl]- hexafluoropropane and various aromatic diamines

Abstract

Two diimide-dicarboxylic acids, 2,2-bis[N-(4-carboxyphenyl)phthalimidyl]hexafluoropropane (p-I) and 2,2,-bis[N-(3-carboxyphenyl)phthalimidyl]hexafluoropropane (m-I), were prepared by azeotropic condensation of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride and p-aminobenzoic acid or m-aminobenzoic acid at a 1:2 molar ratio in N,N-dimethylacetamide/toluene. Two series of organosoluble and colorless poly(amide–imide)s were synthesized from diimide–diacid p-I or m-I with ten kinds of aromatic diamines by direct polycondensation using triphenyl phosphite and pyridine as condensing agents. The thin films cast from N,N-dimethylacetamide were measured by UV–vis spectroscopy and Macbeth color-eye colorimetery, the cutoff wavelengths of almost all the films were below 400 nm (361–389 nm) and the values of the parameter b* were between 15.31 and 34.72; these polymers are much lighter in color than other analogous polymers. Almost all the polymer were soluble in N-methyl-2-pyrrolodone, N,N-dimethylacetamide, N,N-dimethylformamide and dimethyl sulfoxide, and some polymers could dissolve in less polar solvents, such as dioxane and tetrahydrofuran, etc. The cast films exhibited yield strengths of 95–131 MPa, tensile strengths ranging from 92 to 130 MPa, elongations at break from 9 to 27%, and initial moduli from 2.1 to 3.3 GPa. The poly(amide–imide)s had glass-transition temperatures between 259 and 328°C and 10%-weight-loss temperatures above 510 °C in nitrogen and air, indicating excellent thermal stability.