Polyimides derived from bismethylolimides, 3. Synthesis and properties of poly(imide-urethane)s

Poly(imide-urethane)s having a methylene group between the imido and the oxycarbamoyl groups were synthesized by addition polymerization of bis(N-hydroxymethyl)imides and diisocyanates in hexamethylphosphoric triamide. Properties of the resulting poly(imide-urethane)s were studied in comparison with those of the corresponding poly(imide-urethane)s having no methylene group. The resulting carbamic ester linkage was found to be much more stable against nucleophiles compared with the carbamic ester linkage without the methylene group. However, there appeared to be not much difference in thermal stability between these two kinds of linkages.