Kinetics of thermally induced phase separation in ternary polymer solutions. II. Comparison of theory and experiment

Light-scattering measurements and spinodal decomposition modeling have been used to quantify the kinetics of pore growth in thermally quenched polymersolvent-nonsolvent [poly(methyl methacrylate) (PMMA)/1-methyl-2-pyrrolidinone (NMP)/glycerin] solutions. Solutions of fixed composition were quenched to a series of temperatures and light-scattering measurements and model calculations were performed to determine the temperature dependence of the pore growth rate. Both the experimental results and the model calculations show that the growth rate exhibits a maximum at an intermediate quench temperature that is related to an interplay between the thermodynamic and transport effects that govern pore growth. A similar growth-rate maximum is also observed when a series of solutions of varying nonsolvent composition are all quenched to the same temperature. The relevance of these experiments to the dynamics of pore growth and the eventual locking-in of the two-phase structure that forms during nonsolvent-induced phase inversion is discussed. (C) 1999 John Wiley & Sons, Inc.