Phase Separation in Polystyrene/Poly(Vinyl Methyl Ether) Blends as Studied by Excimer Fluorescence

摘要

Excimer fluorescence has been used to study spinodal decomposition in a polystyrene (PS)/poly(vinyl methyl ether) (PVME) blend phase separated by thermal means. From the measurement of the ratio of excimer-to-monomer fluorescence emission intensities, the time dependence of the rich- and lean-phase compositions during phase separation has been determined. Cahn's theory of spinodal decomposition appears to describe adequately the early stages of phase separation. Fluorescence results indicate, however, that equilibrium is not reached during this time period. From the measured growth rate of decomposition, the macroscopic diffusion coefficient for a 10% PS/PVME blend annealed at 423 K is calculated to be of the order -10 to the -11 power/sq cm/s.