Solution polymerization of an alpha,omega-diethynyl diimide to a diacetylene-containing polyimide via oxidative coupling

摘要

The room-temperature solution polymerization of N,N'-dipropargyl(4,4'-hexafluoroisopropylidene)bisphthalimide via oxidative coupling was monitored as a function of time by H-1 NMR spectroscopy and gel permeation chromatography. Following formation of the diacetylene-containing polyimide, the reaction proceeded with hydrolysis of the imide rings, made possible by the presence of the base needed for catalyst formation and water released in the oxidative coupling chain-growth steps. The imide groups could be regenerated either thermally or chemically. Prior to hydrolysis of the imide rings, the polymerization was first-order with respect to both catalyst and functional group concentration, with an intrinsic rate constant of 0.14 l/mol h. For sufficiently long polymerization times, chain scission and molecular weight reduction occurred via hydrolysis of the amide linkages. Thermogravimetric analyses were conducted on the solid products as a function of reaction time. All products could be thermally crosslinked; the thermal stability of the crosslinked monomer was greater than that of the crosslinked polymer. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 17]