Comparison of Mobility Modes in Polymer Solutions Undergoing Thermal-Induced Phase Separation

ABSTRACTThe thermal-induced phase separation method is used to fabricate polymer membranes and polymer-dispersed liquid crystal films from polymer solutions. The resultant morphology consists of solvent droplets dispersed uniformly in a solid polymer matrix. Up till now, the modeling and computer simulation of the thermal-induced phase separation phenomenon in polymer solutions have considered the mobility to be a constant. The objective of this presentation is to compare the following three mobility modes: (1) mobility as a constant, (2) mobility following fast mode theory, and (3) mobility following slow mode theory. We present computer simulation results from models composed of the Cahn-Hilliard theory for phase separation, Flory-Huggins free energy density for polymer solutions, and the three aforementioned mobility modes. The numerical results indicate that there is no significant difference in the morphology formed; the only difference occurs in the phase separation time. Furthermore, the numerical results show that the only difference between the slow and fast mode theories is a factor of two; the mobility of the fast mode theory is twice that of the slow mode theory.