Synthesis and properties of polyurethanes and polyureas containing 2,5-thiophenylene linkage

A novel diisocyanate monomer, thiophene-2,5-diisocyanate (ThDI) was prepared from readily available adipic acid via the intermediate formation of thiophene-2,5-dicarboxylic acid chloride (ThDAC) and thiophene-2,5-dicarboxylic acid azide (ThDAA) which was subjected to a Curtius rearrangement. Polyurethanes and polyureas containing 2,5-thiophenylene linkage were synthesized by the polycondensation of thiophene-2,5-diisocyanate with various diols and diamines, respectively, in N,N-dimethylformamide. Polymerization conditions were optimized and the high yields of polymers were obtained. The identity of ThDI, model compounds, and the resulting polymers was confirmed by elemental analysis and spectroscopic methods. These polyurethanes and polyureas were found to have inherent viscosities in the range of 0.33–0.68 dL/g. Some physical properties of these polymers were also investigated.