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 co polyesters on their sequence order was investigated with the Monte Carlo si mulation 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 copolyester s, miscibility-induced sequential reordering (MISR) was induced. The more r epulsive the pair interaction was, the higher the sequence order was. Durin g the MISR process, homoester-interchange reactions became more favorable b ecause of the repulsive interaction, accompanying the decrease of the inter actional free energy. The sequence order resulting from MISR was independen t of the relative trial ratio of phase separation to ester-interchange reac tion at a given value of interaction energy. Restoration of the sequence di stribution was also simulated with and without the repulsive interaction be tween the components of the binary copolyesters to investigate the effect o f MISR on the crystallization-induced sequential reordering (CISR) process in binary copolyesters, where sequences with lengths longer than 6 were ass umed to crystallize and could not take part in ester-interchange reactions. The sequence distribution in the amorphous phase was restored via ester-in terchange reactions. When the repulsive interaction was applied to binary c opolyesters during the CISR process, restoration of the sequence distributi on was accelerated, indicating that MISR can accelerate the CISR process wh en a polyester blend shows upper critical solution temperature behavior. (C ) 2001 John Wiley & Sons, Inc.