Copolymerization of p-substituted phenylacetylenes

Copolymerization of p-nitrophenylacetylene (M1), an electron-accepting comonomer, and p-aminophenylacetylene (M2), an electron-donating comonomer, has been studied in order to synthesize linear conjugating copolymers. The rate of thermal copolymerization in equi-molar mixture of the comonomers at 160 deg C was greater than that of homopolymerization of each comonomer. The monomer reactivity ratios obtained in the thermal copolymerization were r1 = 0.37 and r2 = 0.17. Gel permeation chromatograms and ultraviolet-visible absorption spectra of the copolymers and the homopolymers showed that the chain lengths of conjugated double bonds of the copolymers obtained by the thermal copolymerization in bulk and by γ-ray-induced copolymerization in methylene chloride were longer than that of poly(nitrophenylacetylene) obtained by the thermal polymerization. The comonomers formed a charge-transfer complex of the molar ratio 1:2 in the liquid phase, but probably it did not participate in the copolymerization. The electric conductivity of the copolymer obtained by thermal initiation at 140 deg C was 5.3 x 10-10 · Ω-1 · cm-1. (author)