Novel polyimides, optionally end-capped with polymerizable or inert groups, and the polyamic acid or ester intermediates thereof are prepared by reacting a tetracarboxylic acid compound (e.g. pyromellitic dianhydride or 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride or its methyl diester) with diamines having the general formula ##STR1## wherein Z is oxygen or sulfur, X and/or Y are carbonyl or carbinol groups, the amine groups may be in the 2-, 3-, and/or 4-position, and isomerism is present when X and/or Y is a carbinol group. The polyimides may be end-capped by reaction, during or after their formation, with polymerizable groups such as 3-aminophenyl acetylene or 3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride. The diamines are novel classes of amines when Z is sulfur and X and/or Y are carbonyl or carbinol groups and when Z is oxygen and X, Y, or X and Y are carbinol groups.