Study of Flexibility of Polymer Chain and intramolecular motion.

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1. The details of dynamic structure of rod-polymer systems have already been studied from both theoretical and experimental points, and it becomes clear that in case of relatively small flexibility the quantitative estimation of dynamic structure factor of semiflexible polymers is possible. Especially, from the experimental results for Collagen with monodisperse length distribution the characterization of semiflexible polymer becomes to be available by use of dynamic light scatttering technique. 2. The optical properties of electrically conducting polymers (poly(arylenes) were examined. These polymers have large degree of depolarization and are soluble in suitable solvents, and it is clarified that these polymers behave as semiflexible polymers from the relation between the solution properties and molecular weight. 3. The solution properties of Poly(Nisopropylacrylamide) systems which show unique thermal response were studied by use of light scattering. In the good solvent state, this polymer shows the similar behavior to usual nonpolar polymer systems, but in the poor solvent state, shows phase transiton independent of the concentration and molecular weight. The process of transition is the coil-globule transition, and due to strong hydrophobic interaction the phase separation occurs. And, introduction of some substitution group causes the change of flexibility of polymer chain and a significant retardation accompanies in the thermal behavior when cooling. 4. The phase transition of DPPC vesicles which is the typical phospholipid membrane bilayer was studied by dynamic light scattering. There were many conflicting results for the phase transition behavior of this systems in terms of light scattering. From the precise results for the monodisperse vesicle samples, it becomes clear that the phase separation behavior strongly depends on the size and size distribution of vesicles and this result explains consistently the results so far.