Spectral studies and thermal properties of a urethane-substituted polythiophene

A new polythiophene containing a urethane side chain in the β-position was chemically polymerized in chloroform using FeCl3 as the oxidant. The urethane-substituted polythiophene is soluble not only in common organic solvents, such as chloroform and tetrahydrofuran, but also in strong polar solvents such as N,N-dimethylformamide, N,N-dimethylacetamide and N-methyl-2-pyrrolidinone. This allows the polymer to be blended with conventional polymers, such as polyurethane, polyacrylonitrile, polyamide, polycarbonate and polyester, in solution while maintaining good electrical conductivity. The structures of the monomer and polymer were characterized using NMR, IR, molecular weight and elemental analysis. The spectral results suggest that the chain order of this polymer is quite regular. Mw and Mn of this polymer obtained by gel permeation chromatography are 169 284 and 63 557, respectively. This polythiophene containing a urethane side chain also demonstrates solvatochromic behavior which was characterized by UV-Vis absorption spectroscopy. Glass transition temperatures obtained by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) studies are 62 and 73 °C, respectively, and the melting point of this polymer measured by DSC is 265 °C. Thermogravimetric analysis results indicate that this polymer is a thermally stable material.