Origin of miscibility‐induced sequential reordering and crystallization‐induced sequential reordering in binary copolyesters: a Monte Carlo simulation

The effect of the repulsive interaction between the components of binary copolyesters on their sequence order was investigated with the Monte Carlo simulation method. The phase separation and ester-interchange reactions were implemented simultaneously with a kind of one-site bond fluctuation model. When the repulsive interaction energy was applied to the binary copolyesters, miscibility-induced sequential reordering (MISR) was induced. The more repulsive the pair interaction was, the higher the sequence order was. During the MISR process, homoester-interchange reactions became more favorable because of the repulsive interaction, accompanying the decrease of the interactional free energy. The sequence order resulting from MISR was independent of the relative trial ratio of phase separation to ester-interchange reaction at a given value of interaction energy. Restoration of the sequence distribution was also simulated with and without the repulsive interaction between the components of the binary copolyesters to investigate the effect of MISR on the crystallization-induced sequential reordering (CISR) process in binary copolyesters, where sequences with lengths longer than 6 were assumed to crystallize and could not take part in ester-interchange reactions. The sequence distribution in the amorphous phase was restored via ester-interchange reactions. When the repulsive interaction was applied to binary copolyesters during the CISR process, restoration of the sequence distribution was accelerated, indicating that MISR can accelerate the CISR process when a polyester blend shows upper critical solution temperature behavior. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1337–1347, 2001