Dynamic light scattering from polystyrene-poly(methylmethacrylate) diblock copolymer in toluene

The dynamical behavior of the diblock copolymer polystyrene-poly(methylmethacrylate) (PS-PMMA) in toluene has been investigated by quasielastic light scattering. Two distinct modes have been observed in the autocorrelation function of the scattered light. In the semidilute range, at one polymer concentration c>c^* (where c^* is the overlap concentration) and far from the microphase separation, the variation of the two relaxation processes characterized by their frequencies Γ,Γ’ and their amplitudes A,A’ has been examined as a function of the scattering vector ‖q‖. The experimental results are in good agreement with the theoretical predictions.