Effects of solvent and temperature on regioregularity of poly(3-hexylthiophene-2,5-diyl) prepared by chemical oxidative polymerization

Chemical oxidative polymerization (COP) of 3-hexylthiophene in polar solvents, such as CH3CN and CH2Cl2, smoothly proceeded at temperatures below 0 °C to afford regio-controlled poly(3-hexylthiophene-2,5-diyl) (P3HexTh) with a head-to-tail (HT) content of higher than 80%. Use of CH3CN at −40 °C gave P3HexTh with 83% HT content, Mn (number-average molecular weight) of 42 000, and a relatively narrow polydispersity of 1.6. Obtained P3HexTh formed an ordered structure in solid, and NOBF4-treated film of P3HexTh with the HT content of 83% showed electrical conductivity of 3.0 S cm−1.