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

The room-temperature solution polymerization of N,N'-dipropargyl(4,4'-hexaf luoroisopropylidene)bisphthalimide via oxidative coupling was monitored as a function of time by H-1 NMR spectroscopy and gel permeation chromatograph y. Following formation of the diacetylene-containing polyimide, the reactio n proceeded with hydrolysis of the imide rings, made possible by the presen ce of the base needed for catalyst formation and water released in the oxid ative coupling chain-growth steps. The imide groups could be regenerated ei ther thermally or chemically. Prior to hydrolysis of the imide rings, the p olymerization was first-order with respect to both catalyst and functional group concentration, with an intrinsic rate constant of 0.14 l/mol h. For s ufficiently 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 tim e. All products could be thermally crosslinked; the thermal stability of th e crosslinked monomer was greater than that of the crosslinked polymer. (C) 2000 Elsevier Science Ltd. All rights reserved.