Poly(ether-imide) and poly(ether-imide)-polydimethyl-siloxane containing isopropylidene groups

摘要

A poly(ether-imide) was prepared by thermal imidization of poly(amic-acid) intermediate resulting from the solution polycondensation reaction of a bis(ether-anhydride),namely 2,2'-bis-[(3,4-dicarboxyphenoxy)phenyl]-l,4-phenylene-diisopro-pylidene dianhydride,with an aromatic diamine containing two isopropylidene groups,namely 4,4'-(l,4-phenylenediisopropylidene)bisaniline.A poly(ether-irnide)-polydimethylsiloxane copolymer was prepared by polycondensation reaction of the same bis(ether-anhydride) with an equimolar quantity of the aromatic diamine having isopropylidene groups and a bis(aminopropyl)polydimethylsiloxane oligomer of controlled molecular weight.A solution imidization procedure was used to convert quantitatively the poly(amic-acid) intermediates to the corresponding polyimides.The polymers were easily soluble in polar organic solvents and showed good thermal stability with decomposition temperature being above 400°C.Electrical insulating properties of poly(ether-imide)-polydimethylsiloxane copolymer film were evaluated on the basis of dielectric constant and dielectric loss and their variation with frequency and temperature.