ABSTRACT
Acknowledgements............................................................................ 191
Glossary of Sym bols.......................................................................... 191
References........................................................................................... 193
1 Introduction
Light is scattered from a fluid medium because of variations in the dielectric constant with position in the medium. The application of static light scattering (SLS) to dilute polymer solutions and multicomponent simple mixtures was developed by Zimm,1 Debye,2 Stockmayer,3 and
Kirkwood and Goldberg.4 More recently, Benoît and coworkers5’6 pre sented a general expression for SLS from a solution of homopolymers and copolymers in a solvent at arbitrary large concentrations. The phe nomenological interpretation of dynamic light scattering (DLS) is that scattered light intensity fluctuations are caused by variations of the local dielectric constant in time within a quiescent equilibrated medium. These variations are due to hydrodynamic fluctuations of pressure, temperature and concentrations.7-9 The pressure fluctuations lead to scattered light at frequencies shifted up and down from the monochromatic frequency of the incident beam and produce the Brillouin peaks.9 In polymer solu tions, the scattered light caused by the temperature fluctuations decay typically on a much faster time scale than the concentration fluctuations that are detected by photon correlation spectroscopy.9 Thus, to a very good approximation, the analysis of photon correlation DLS from polymer solutions can be carried out by considering the dynamics of concentration fluctuations in the system.
