CRITICAL FLUCTUATIONS IN TERNARY POLYMER-SOLUTIONS

The dynamics of critical fluctuations and spinodal decomposition in ternary mixtures of two polymers and a solvent are studied. The special case of a symmetrical mixture where concentration and composition fluctuations are decoupled is considered. The dynamical structure factor S(I)(q,t) which is directly measurable in the zero-average contrast condition is examined in detail. Its decay rate GAMMA(I) is calculated in the presence of hydrodynamic interaction, and various scaling properties with the wavevector q are identified. These are found to be sensitive to the approximation made for the chain form factor P(q), and a particular scaling not found in polymer blends is obtained in the intermediate q-range. The hydrodynamic interactions identified with mode coupling effects in critical mixtures are also discussed in detail. The kinetics of spinodal decomposition in the early stages is examined only in the linear approximations.