Miscibility-induced sequential reordering in random copolyesters: A Monte Carlo simulation

Miscibility-induced sequential reordering (MISR) was investigated using a M onte Carlo simulation method in two systems, i.e., a ternary copolyester sy stem and a binary copolyester system in the presence of a third noncondensa tion polymer. A homogeneous AB random copolymer/C homopolymer blend was use d as an initial blend. Phase separation and ester-interchange reactions wer e performed simultaneously at a trial ratio of 100/1 using a one-site bond fluctuation model, MISR was monitored by calculating the number-average seq uence length of each segment. In the case of the ternary copolyester system , ester-interchange reactions between segments A, B, and C were attempted u nder various attractive and repulsive interaction energies between the thre e. It was found that MISR of segment A was induced only when segment C was miscible with segment B. The more repulsive segments A and C are and the mo re attractive segments B and C are, the longer the sequence length of the s egment A becomes. In the case of a binary copolyester system in the presenc e of a third noncondensation polymer, segment A or B is sequentially reorde red, accompanied by phase separation of the blend, when segment C is miscib le with either segment A or B, respectively. The more repulsive the interac tion between segments A and C is and the more attractive the interaction be tween segments B and C is, the longer the sequence length of segments A and B becomes.