Kinetic study of the formation of aromatic polyimides based on multinuclear bridge-containing aromatic diamines

Abstract

A method of IR analysis was used in a kinetic study of reactions of dianhydrides of 1,3-bis-(3,4-dicarboxyphenoxy)benzene and 3,3′,4,4′-tetracarboxybenzophenone with aniline and its p-methyl-, p-phenoxy-, p-bromo-, p-nitro derivatives and tetranuclear bridge-containing diamines in N,N-dimethylacetamide (DMAA) at 298 K. A PMR study was made of the kinetics of cyclization of o-carboxyamides prepared from the dianhydride of 1,3-bis(3,3-dicarboxyphenoxy)benzene and the above-mentioned diamines in DMAA solution at 433 K. The effect of a substituent in the nucleophile (amine) on rates of acylation with tetracarboxylic dianhydrides is described by a Hammett equation with p=−3·6 and −3·4 respectively. The rate of cyclization is only slightly depend on the initial amine structure. The p value for cyclization of the model o-carboxyanilides is equal to −0·2. In the case of the studied flexible-chain polymers the rates of formation and cyclization of polyamic acids depend on factors relating to the electronic structure of the reacting functional groups.