Novel, high molecular weight aromatic-aliphatic poly(enaminonitriles) (PEANs) were prepared by the interfacial polymerization of 4 aromatic bis(chlorovinylidene cyanide) monomers with linear, aliphatic diamines containing 6, and 8-12 methylene units. Characterization was done with TGA, DSC, solution viscometry, GPC and spectroscopic methods. The PEANs displayed excellent solubility in polar aprotic solvents and showed good thermal stability (5% weight loss >325 degrees C) considering the aliphatic content of the chains. The polymers appeared to be completely amorphous and showed no melting transitions by DSC. Molecular modeling studies suggested that steric interference caused by the 2,2-dicyanovinyl functionality may hinder the formation of crystalline regions. (C) 2000 Elsevier Science Ltd. All rights reserved.