Polyimides prepared without the use of toxic amidic solvents

Abstract

Polyimides and their modified forms (e.g., poly(imide-siloxanes)) are an important class of unique polymers. Their typical two-step preparation includes the preparation of a solution of the polyimide precursor in an amidic solvent (e.g., N-methyl-2-pyrrolidone, N,N-dimethylacetamide). Currently, these solvents are classified as toxic, and there is a strong demand to limit their use. Therefore, this study addresses the preparation of polyimides by nontoxic γ-butyrolactone as a solvent and the synthesis of polyimides and poly(imide-siloxanes) in the presence of an enzyme without the use of a solvent. The ability of these products to form self-standing films (membranes) and their thermal and mechanical properties have been found, at least partly, to be comparable to those of the products prepared by using traditional amidic solvents.