| The study of the surface hydrodynamics of polymer solutions is relevant to various applications involving polymer liquids. Theoretically, we have calculated the surface laser light scattering (SLLS) spectrum using surface hydrodynamic equations appropriate for linear viscoelastic fluids; experimentally, we have carried out detailed SLLS studies of various systems ranging from soluble diblock copolymer surfactant (PEO-block-PDMS/water), polymer with strong surface adsorption (PVP/water), to polymer of negligible surface adsorption (PIB/decane). In the PEO-block-PDMS/water system, the surface elastic modulus deduced from the SLLS spectrum exhibits a maximum at a certain concentration. In the PVP/water system, the PVP shows an additional adsorption at the concentration over the C*; during the whole concentration range we have studied, no evidence of the capillary to elastic wave evolution has been observed. In the PIB/decane system, there is no surface adsorption, the low surface tension of decane allows a clear-cut capillary wave to elastic wave cross-over to be experimentally observed in this system.;SLLS has also been used to investigate the surface tension relaxation dynamics at the interface of the air/PNIPAM-water solutions. Our results are consistent with a model invoking three consecutive stages previously proposed by Nahringbauer for surface tension relaxation process.;Dynamic light scattering studies of polystyrene in THF, in 1,4-dioxane (DO) and in THF/DO mixed solvents, subject to an external dc field, have been carried out. In THF, the rate constant for the decay of the intensity autocorrelation function is found to increase with an increase in the external electric field; in DO, the electric field is found to have only a negligible effect; in the mixed solvent it exhibits an intermediate effect, depending on the THF content. |
