Effect of copolymer compatibilizer sequence on the dynamics of phase separation of immiscible binary homopolymer blends

We present the results of kinetic Monte Carlo simulations aimed at exploring the effect of copolymer sequence distribution on the dynamics of phase separation of an immiscible A/B binary homopolymer blend. Diblock, protein-like copolymers (PLCs), simple linear gradient, random, and alternating copolymers having equal number of A and B segments, identical chemical composition, and chain length are considered as compatibilizers. All copolymers, irrespective of their sequence, retard the phase separation process by migrating to the biphasic interface between the A/B interface, thereby minimizing the interfacial energy and promoting adhesion between the homopolymer-rich phases. As expected, diblock copolymers perform the best and each block of the diblock copolymer penetrates the energetically favorable homopolymer-rich phase. Alternating copolymers lie at the interface and PLCs, simple linear gradient, and random copolymers weave back and forth across the interface. The weaving and penetration is more pronounced for PLCs than for simple linear gradient and random copolymers. Judging by the contact analysis, extension and conformation of the copolymers at the interface, and structure factor calculations, it is evident that for the chain lengths considered in our simulations, PLCs are better compatibilizers than alternating and random copolymers, while being on a par with simple linear gradient copolymers, but not as good as diblocks.