PHYSICAL ORIGIN OF THE LOCAL RIGIDITY OF CONJUGATED POLYMERS IN GOOD SOLVENT

We report small angle neutron scattering measurements on several conjugated and saturated polymers in solution with different substituent side-groups. We show that the statistical conformation can be described either by a ribbon structure with torsional fluctuations or an helical at short scale, the difference depending on the chemical structure of the side groups. In both cases, the stastistical length is shown to be strongly dependent on the size of the side-groups and the average torsion between monomer units.