Addition polymerization of 1,4‐diethynylbenzene with 1,4‐benzenedithiol and properties of the resulting copolymer

A novel addition polymerization of 1,4‐diethynylbenzene (1) with 1,4‐benzenedithiol (2) was studied under UV‐irradiation in toluene solution at −20°C. The addition polymerization was found to proceed rapidly and a pale‐yellowish polymer precipitated with the progress of the reaction (M̄n = 7500). A soluble polymer was recovered from the toluene solution by evaporation. Its M̄n value was estimated to be 3000. When an excess amount of 2 was used (mole ratio 1:2 = 2:3), the yield of the insoluble polymer increased. TG of the polymer indicated its decomposition point to be ≈500°C in air. The electroconductivity of the insoluble and soluble polymers was found to be 10−2 S · cm−1 and 10−5 S · cm−1 when doped with I2 at room temperature, respectively, and the conductivity was reversibly increased with increasing temperature up to 90°C. At T > 90°C the iodine was released and the conductivity decreased.