One-pot synthesis of an alternating copolyimide based on regioselective reaction of a non-symmetrical alicyclic dianhydride

Four constitutionally isomeric copoly(amide acid)s (coPAAs), two alternating and two random, have been successfully obtained from the same combination of one non-symmetrical alicyclic tetracarboxylic dianhydride (1.0 molar equivalents) and two symmetric aromatic diamines (0.5 molar equivalents each) by only slightly changing the reaction procedures. When the reaction mixture is subjected to chemical imidization conditions without isolation of coPAAs, the corresponding copolyimides (coPIs) are obtained in one pot. All of the coPIs are slightly yellow amorphous powders and the solubility of them is similar to each other. The glass transition temperatures of the alternating coPIs are lower in comparison to those of the random coPIs.