Perfectly Alternating Segmented Polyimide Siloxane Copolymers

Abstract

Perfectly alternating segmented, fully cyclized, polyimide siloxane copolymers were synthesized and characterized as new materials. The reaction utilized the transimidization of aminopropyl terminated polydimethyl siloxane oligomers with aminopyridine capped polyimide oligomers based on oxydiphthalic anhydride and bisaniline P. The reaction was conducted in refluxing chlorobenzene at about 130°C. Transimidization processes with the aliphatic amine end group appear to be quite rapid under these conditions, and high molecular weight copolymers were achieved in times as short as 10 minutes. The resulting copolymers could be cast or melt pressed into transparent films whose thermal and mechanical properties reflected the composition and block molecular weights. In general, the reactions proceeded smoothly under homogeneous conditions in chlorobenzene and produced materials with glass transition temperatures somewhat depressed from the glass transition temperatures of the starting polyimide oligomers. The method allows excellent control of the microphase morphology, which is a function of block size and interaction parameters. The synthesis and characterization of these materials will be discussed.