Preparing organosoluble aromatic polyimides based on 3,3?,5,5?-tetrabromo-2,2-bis[4-(4-aminophenoxy)phenyl]propane and aromatic dianhydrides

Abstract

A new aromatic diamine, with an isopropylidene and bromo-substituted arylene ether structure, 3,3′,5,5′-tetrabromo-2,2-bis[4-(4-aminophenoxy)phenyl]propane, was synthesized by the nucleophilic substitution reaction of p-chloronitrobenzene with 3,3′,5,5′-tetrabromobisphenol A, followed by a catalytic reduction of the resulting dinitro compound. Novel aromatic polyimides with inherent viscosities ranging from 0.53 to 2.1 dL/g were then obtained by a one-step or two-step polymerization process with this diamine and various aromatic dianhydrides. These bromine-containing polyimides showed typical amorphous diffraction patterns and were readily soluble at room temperature in N-methyl-2-pyrrolidone, N,N′-dimethylformamide, N,N′-dimethylacetamide, and even in less polar solvents such as chloroform, tetrahydrofuran, and pyridine. They also dissolved in dimethyl sulfoxide, m-cresol, o-chlorophenol, or concentrated sulfuric acid with heating. Glass-transition temperatures were 272–303 °C, depending on the nature of the dianhydride moiety. Thermogravimetric analysis showed that all the polymers were thermally stable, with 10% weight loss occurring between 465 and 499 °C in nitrogen and between 457 and 492 °C under atmospheric conditions. The bulky bromine substituents not only increased the solubility but also compensated for the loss of thermal properties caused by the flexible ether linkage. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1662–1674, 2001