NOVEL POLYIMIDE IONENE - SYNTHESIS AND CHARACTERIZATION OF POLYIMIDES CONTAINING AROMATIC BIPYRIDINIUM SALT

摘要

A series of 4,4'-(1,4-phenylene)-bis(N-aminoaryl-2,6-diphenyl pyridinium perchlorate)s were synthesized by the reaction of 4,4'-(1,4-phenylene)-bis(2,6-diphenyl pyrylium) with aromatic diamines. They were used as monomers to react with various aromatic tetracarboxylic dianhydrides, to prepare polyimides via a two-stage procedure that included a ring-opening condensation in N,N-dimethylformamide (DMF) to give poly(amic acid)s, followed by thermal cyclodehydration to polyimides. The inherent viscosities of these poly(amic acid)s and polyimides were in a range of 1.03-0.07 dl g(-1) (0.5% in DMF at 25 degrees C). All polyimides had good solubilities in several polar aprotic solvents, such as DMF, N,N-dimethylacetamide (DMAc), etc. Polyimides derived from 4,4'-oxydiphthalic anhydride could form transparent flexible and tough films. They had a tensile strength range of 42-80 MPa, and an elongation around 5%. The glass transition temperatures of all polyimides were between 181 and 206 degrees C (differential scanning calorimetry). Thermogravimetric analyses indicated that they were fairly stable up to 300 degrees C, and 5% weight loss temperatures were recorded in the range of 337-367 degrees C in nitrogen. These polyimides were semi-conductors with conductivities around 10(-8) ohm(-1) cm(-1) and their conductivities could be further increased up to 10(-7) ohm(-1) cm(-1) by I-2-doping. These bipyridinium-based poly(amic acid)s and polyimides could reversibly develop colour by u.v. irradiation. (C) 1997 Elsevier Science Ltd. [References: 12]