INVESTIGATIONS OF STIFF-CHAIN POLYMERS IN SOLUTION

The shape and the conformation of stiff-chain polyesters and polyimide s substituted by flexible side chains are reviewed and discussed. The shape of the dissolved macromolecules has been assessed by small-angle neutron scattering whereas the persistence length was determined by v iscosimetric means. For all systems under consideration here the persi stence length is found to be of the order of 10nm. This finding is in agreement with recent computer simulation indicating that bond angle a nd out-of-plane fluctuations lead to considerable deviations from the rodlike shape of the main chains.