Linear and networked blends and copolymers of polyimide

Abstract

Preparation and characterization of blends and copolymers of a fluorinated polyimide with network constituents is reported. 4,4′- Hexafluoroisopropylidene diphthalic anhydride and 4,4′-diaminodiphenyl ether (6FDA-DDE) polyimide were used as the linear hosts and mellitic acid hexamethyl ester - 4,4′-diaminodiphenyl ether (MAHE-DDE) was employed as the network constituent for the blend and copolymer. Cast films of the polyimides were characterized by FTIR, XPS, DMA, and TGA. The multifunctional nature of MAHE facilitated crosslinking among the constituents. Both blends and copolymers showed significant improvement in the storage modulus and glass transition temperature relative to that observed for the 6FDA homopolymer. The occurrence of a single glass transition temperature for the blends suggests that they were at least partially miscible. Presence of low molecular weight species in the copolyimides, combined with steric hindrance to crosslinking, may have resulted in the existence of an optimum in the amount of the network components for improving the mechanical properties. Inclusion of network components is presented as a facile method for improving the desirable properties of polyimide. © 2006 Wiley Periodicals, Inc.