Interfaces in partly compatible polymer mixtures: A Monte Carlo simulation approach

TL;DR

This paper uses Monte Carlo simulations to study the structure of polymer coils and diblock copolymers near interfaces in partly compatible polymer mixtures, revealing orientation and stretching behaviors.

Contribution

It provides detailed simulation data on polymer and diblock structures at interfaces, comparing results with self-consistent field theory predictions.

Findings

Homopolymer coils align parallel to the interface in strong segregation.

Diblocks form perpendicular 'dumbbell' structures at the interface.

Diblocks are weakly stretched in the dilute 'mushroom' regime.

Abstract

The structure of polymer coils near interfaces between coexisting phases of symmetrical polymer mixtures (AB) is discussed, as well as the structure of symmetric diblock copolymers of the same chain length N adsorbed at the interface. The problem is studied by Monte Carlo simulations of the bond fluctuation model on the simple cubic lattice, using massively parallel computers (CRAY T3D). While homopolymer coils in the strong segregation limit are oriented parallel to the interface, the diblocks form ``dumbbells'' oriented perpendicular to the interface. However, in the dilute case (``mushroom regime'' rather than ``brush regime''), the diblocks are only weakly stretched. Distribution functions for monomers at the chain ends and in the center of the polymer are obtained, and a comparison to the self consistent field theory is made.