Dynamics of concentration fluctuation in a polymer blend on both sides of the phase boundary

The dynamics of concentration fluctuation in a deuterated polystyrene/poly(vinylmethylether) blend system has been studied by the temperature jump and also by the reverse quench light scattering techniques. The growth or decay rate R(q) in Cahn–Hilliard–Cook’s equation is almost proportional to the square of scattering wave vector. This indicates that the interfacial free energy contribution to the concentration fluctuation dynamics in the wavelength range examined is very small. The interdiffusion coefficient D which has been obtained as a function of temperature, is continuous at the phase separation boundary. The mobility M, which can be extracted from D by combining the results of both statics and kinetics has an Arrhenius type of temperature dependence on both sides of the phase boundary.