HYDRODYNAMIC SURFACE-WAVES IN CONCENTRATED POLYMER-SOLUTIONS IN THE PRESENCE OF SURFACE-ADSORPTION

A theory of light scattering fram the polymer solution/air interface t hat includes the effect of surface adsorption is developed. The polyme r solution is assumed to exhibit a linear viscoelastic response. The s urface laser Light scattering (SLLS) spectrum is calculated from surfa ce hydrodynamic equations appropriate for linear viscoelastic fluids u sing the method of initial value problems. Numerical calculations are made to Investigate the effects of surface tension and dilational modu lus 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 i ncreasing dilational modulus as a result of surface adsorption. The tw o-peak structure is, however, found to be much less pronounced in a so lution with a low surface tension solvent. (C) 1997 American Institute of Physics.