Interfaces between coexisting phases in polymer mixtures: What can we learn from Monte Carlo simulations?

Abstract

AbstractSymmetric binary polymer mixtures are studied by Monte Carlo simulation of the bond fluctuation model, considering both interfaces between coexisting bulk phases and interfaces confined in thin films. It is found that the critical behavior of interfacial tension and width is compatible with that of the Ising model, as expected from the universality principle. In the strong segregation limit, only qualitative but not quantitative agreement with the self‐consistent field (SCF) theory is found. It is argued that the SCF theory requires magnified image but for the short chains studied (N = 32 effective monomer units per chain), the limit is only reached for magnified image close to unity. Also, the effective χ‐parameter decreases in the interface. It is shown that the interfacial width w does not increase by the adsorption of block copolymers as long as their areal density is still dilute (“mushroom” regime). But a broadening of interfaces does occur for thin films confined between walls at distance D, due to fluctuations that lead to magnified image for short‐range forces, in agreement with experiment.