Computer simulation of phase separation in binary polymer mixtures

Phase separation of binary polymer mixtures was numerically simulated by solving the time‐dependent Langevin equation with Flory–Huggins free energy in two dimensions by using a finite difference method. Spinodal decomposition following structure coarsening was calculated. Simulation results were verified by evaluating the evolution of the wave number obtained from the calculated phase structure by Fourier transformation. Then, computer experiments were carried out to investigate effects of volume fraction and polymer characters, the number of segments, and solubility parameter on morphology. The phase separation time, when the phase began to separate, decreased with deviating volume fraction from 0.5 and with decreasing number of segments and difference between solubility parameters. The difference between solubility parameters had the largest influence on the phase separation time among them and had two effects, the acceleration of phase separation and the restriction of structure coarsening. © 1995 John Wiley & Sons, Inc.