Kinetics of spinodal decomposition in homopolymer solutions and gels

When a binary mixture is quenched to a temperature in the two-phase, thermodynamically unstable region beyond the spinodal, it phase separates into two phases by the process of spinodal decomposition. Light scattering provides a convenient tool to observe the growth of phase-separated domains in polymeric systems. Key theoretical ideas on the kinetics of spinodal decomposition are reviewed and their applicability to polymer solutions and gels is explored in some detail. A review of the time-resolved small-angle light-scattering data on polymer solutions is presented; both agreements and deviations from current theoretical predictions are discussed. In the case of gels the behavior depends on whether the gel is irreversible or thermoreversible. For the latter case, the process of phase separation can be arrested in some intermediate state upon the onset of gelation, lending to a microphase-separated material. Future areas of opportunity in the study of phase-transition kinetics are identified.