The correlation between electrical properties and structure of substituted polyacetylenes

The electrical conductivity of polyphenylacetylenes and polyhalophenylacetylenes was measured in dependence on the temperature and on the type of catalyst used for polymerization. The electrical conductivity increased with increasing temperature. The energy gap was calculated from the temperature dependence on the electrical conductivity; it decreased with increasing number of conjugated double bonds in the polymer chain and with the regularity of structure of the polymer. The number of double bonds, cyclization and configurations were determined by 1H and 13C-NMR. In polyphenylacetylenes only aliphatic carbons deriving from cyclohexadiene units were found but no such units were found in polyhalophenylacetylenes. By UV-vis measurement the number of conjugated double bonds in segments was estimated. The synthesized polymers were amorphous. Their molecular weight was between 2000 and 74.000