SYNTHESIS AND THERMOCHEMISTRY OF PHENYLMALEIMIDE-TERMINATED AND PHENYLNADIMIDE-TERMINATED BISPHENOL-A POLYCARBONATES

Phenylmaleimide (PMI)- and phenylnadimide (PNI)-terminated bisphenol A polycarbonates (PCs) were prepared by solution or interfacial phosgen ation processes, and their thermal crosslinking, both with and without a free radical initiator, and the thermal stability of the resultant network polymers were investigated. m-PMI PCs were prepared by interfa cial phosgenation of bisphenol A and m-hydroxyphenylmaleimide, but p-h ydroxyphenylmaleimide caused rapid phosgene hydrolysis under interfaci al conditions and PCs from it could only be made by solution phosgenat ion. The degree of crosslinking of PMI PCs, as measured by their gel f raction, heated in the absence of a free radical initiator was general ly higher at 250 degrees C than at 300 degrees C and increased with th e concentration of PMI end groups. m- and p-PMI PCs form thermosets ha ving nearly complete gel fractions by radical initiated curing at 150- 200 degrees C. The gel fraction of these thermosets decreases with exp osure to higher temperatures (300 degrees C). This behavior is attribu ted to BA PC chain degradation induced by nitrogen-containing maleimid e reaction products. p-PNI PC was prepared by solution phosgenation an d the thermal reaction of it in the presence of the initiator produced only a small increase in molecular weight. (C) 1997 John Wiley & Sons , Inc.