Linear aromatic poly(amideimide)s having latent maleimide endgroups

A straight-chain aromatic poly(amideimide) having latent maleimide endgroups, comprising the copolymerizate of the following reactants (i), (ii) and (iii):

• (i) a diisocyanate of the formula:
• ##STR17## in which the symbol A is a single valence bond or one of the groups:
• ##STR18## (ii) a monoanhydride of a tricarboxylic acid of the formula:
• ##STR19## in which the symbol B is a substituted or unsubstituted trivalent aromatic radical having at least 6 carbon atoms, or two such radicals bonded together by a single valence bond or one of the groups:
• ##STR20## (iii) a carboxylic monoacid which comprises a latent maleimide function, of the formula:
• ##STR21## in which the symbol R.sub.1 is a methyl radical;
• n is an integer equal to 0, 1, 2 or 3;
• the symbol E is a single valence bond or a group --CH.sub.2 --and is in the ortho-, meta- or para-position relative to the carbon atom of the benzene ring bonded to the group COOH;
• and the symbol D is one of the divalent radicals:
• ##STR22## wherein the symbols R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7, which may be identical or different, are each a hydrogen atom or a straight or branched chain alkyl radical having from 1 from 4 carbon atoms and the symbol F is an oxygen or sulfur atom;
• with the proviso that the respective proportions of the comonomers (i) and (ii) are such that the ratio r:
• ##EQU4## ranges from 1.05/1 to 2.1;
• and the proportion of the comonomer (iii) is such that the ratio r':
• ##EQU5## is equal to 2.