Abstract: The dynamic light scattering technique of photon correlation spectroscopy (PCS) is a sensitive and noninvasive method of probing spontaneous fluctuations in macromolecular solutions. PCS was used to study the wavevector dependence (wavevector magnitude, q) for a wide range of q of intracoil relaxations for a very large, linear polystyrene in both good and theta solvents and a clear coupling between intracoil excluded volume behavior and hydrodynamic interactions was observed. Moreover, the marked concentration dependence of the overall intracoil relaxation for the same polystyrene in good solvent revealed the important role strong intercoil interactions, i.e. `collisions,' played in this system while the absence of this dependence and thus of collisions, in the corresponding theta system highlighted the important role played by thermodynamics in determining the magnitude of the effect of intercoil behavior on intracoil behavior. These results were also consistent with those of an earlier study of coil-coil interactions in dilute solution in which it was also found that thermodynamics played the dominant role. !5
展开▼
