Hydrodynamic surface waves in concentrated polymer solutions in the presence of surface adsorption

A theory of light scattering fram the polymer solution/air interface that includes the effect of surface adsorption is developed. The polymer solution is assumed to exhibit a linear viscoelastic response. The surface laser Light scattering (SLLS) spectrum is calculated from surface hydrodynamic equations appropriate for linear viscoelastic fluids using the method of initial value problems. Numerical calculations are made to Investigate the effects of surface tension and dilational modulus on the SLLS spectrum. The results show that the SLLS spectrum rum polymer solutions having a high surface tension solvent displays a two-peak structure. The high-frequency peak exhibits more capillary wave character, and diminishes rapidly with decreasing surface tension or increasing dilational modulus as a result of surface adsorption. The two-peak structure is, however, found to be much less pronounced in a solution with a low surface tension solvent. (C) 1997 American Institute of Physics.