| abstract |
An N-substituted polyamide-imide essentially composed of identical or different repeating units of the formula I ##STR1## where R 1 is one of the following tetravalent aromatic radicals ##STR2## and X is a bond or one of the following linkers ##STR3## where R 2 and R 4 are each, independently of one another, one of the following divalent aromatic radicals ##STR4## and where X has the abovementioned meanings and where R 3 is hydrogen or a monovalent radical such as C 1 -C 6 -alkyl or phenyl, and the C 1 -C 6 -alkyl-, C 1 -C 6 -alkoxy-, aryl- or halogen-substituted derivatives thereof, and precursors (monomers) therefor, are described. |