QUASI-ELASTIC LIGHT-SCATTERING FROM POLY(DIMETHYLSILOXANE) POLY(METHYL METHACRYLATE) CHLOROFORM UNDER THE OPTICAL THETA CONDITION

Quasielastic light scattering data are reported for a symmetrical mixture of PDMS/PMMA/chloroform satisfying the optical THETA condition. The measurements are made for several polymer concentrations ranging from approximately the overlap concentration to below the critical concentration for phase separation. The data are analyzed using a simple theory based on the random phase approximation. The Rouse model is sufficient to fit qualitatively the data, showing that hydrodynamic interaction is screened in the investigated range of concentration.