CONFORMATION OF SUBSTITUTED POLYACETYLENES IN SOLUTION - RELATIONSHIP BETWEEN ELECTRONIC-PROPERTIES AND LOCAL ORDER

A study of the chain conformation in solutions of polyphenylacetylene and poly(2-octyne) has been performed. The two polymers differ in many ways: polyphenylacetylene gives a red solution while poly(2-octyne) is transparent and, a marked difference on the chain rigidity is observed: the statistical length are 45 angstrom and 135 angstrom respectively. From the study of these two systems, one deduces that curvature fluctuations play a minor role on the pi electrons localization, and that the torsion between monomer units is the pertinent parameter to understand the chain conformation and the pi-electrons localization.