Phase Separation in Polymer Solutions under Extension

Abstract

The results obtained recently by the authors during investigation of the phase behavior of polymer solutions under uniaxial tension are reviewed. The main attention is given to the dilute solutions of unentangled semiflexible macromolecules. The effect of the solution extension rate on the coil–stretched coil transition for semiflexible chains is considered, and stability of the system of stretched coils is analyzed in terms of their segregation followed by formation of the concentrated polymer phase. The spinodal and binodal of the system are determined depending on temperature and extension rate. The kinetics of solution segregation to polymer and solvent, where three stages, namely, (i) spinodal decomposition accompanied by the formation of regions with increased and reduced polymer contents, (ii) formation of the microfibrillar network, and (iii) network collapse yielding separation of the solvent from the polymer phase are identified, is described.