Phase-separation kinetics in dynamically asymmetric binary fluids: Viscoelastic effects in polymer solutions

Abstract

The strong asymmetry in molecular dynamics between the two components of a binary mixture leads to a strong kinetic coupling between the stress field and the order parameter (concentration). which significantly affects the phase separation. A polymer solution. as a typical example of dynamically asymmetric mixtures. behaves as a gel in the initial stage of phase separation for a deep quench, while it behaves as a simple viscous fluid in the final stage. In the intermediate stage. the relaxational nature Of the viscoelastic ellect plays an imporumt role in pattern evolution. which violates the self-similarity of the growing pattern. To understand the phenomena a concept ofdynamic symmetry should be introduced in addition to the static composition symmetry.