Molecular simulation of structural properties of polymer blend nanofilms

Monte Carlo simulation of coarse-grained polyethylene-like models was employed to study the structural properties of polymer blend nanofilms. For homopolymer films with stronger interchain interaction, the densities in the bulk region are increased and the films become thinner accompanied by sharper surface profiles. For polymer blend films, polymer species with weaker interchain interaction preferably migrate to the surface region while the other components tend to locate near the center of the film. For stronger chain interaction, chain ends are more segregated at the surface while the middle beads are depleted. With increasing interchain interaction, there is a higher degree of anisotropic orientation at the bond and chain scale in the surface region. Compared to homopolymer films, chain dimension and shape become more distorted as a function of interchain interaction, especially in the surface region, and exhibit more anisotropic changes in the perpendicular direction to the surface. The longest principal axes of polymer chains are preferably aligned in the parallel direction to the surface and then changed toward isotropic random arrangement in the interior of film structures. Polymers adopt more gauche conformation with better chain packing for films with strong interchain interaction.

Automated summary

Monte Carlo simulation was used to study the structural properties of polymer blend nanofilms with coarse-grained polyethylene-like models. The results showed that the densities in the bulk region increased and the films became thinner with sharper surface profiles for homopolymer films with stronger interchain interaction. For polymer blend films, components with weaker interchain interaction migrated to the surface region, while others located near the center. Increasing interchain interaction resulted in a higher degree of anisotropic orientation and distortion in chain dimension and shape, especially at the surface region.