Monte Carlo study of polymer chains end-grafted onto a spherical interface.

Abstract

We report results from a Monte Carlo simulation of many polymer chains end-grafted onto the outer surface of a sphere. We find that for small values of the radius of the grafting sphere, the monomer density profiles are quite different from what is obtained in the case of a flat interface. As the radius of the sphere is increased further, we find that the profiles resemble those obtained in the flat case. However, even for a large value of the radius, the density profiles cannot be described by a parabolic form. We have also studied the scaling behavior of the density profile and find that the scaling hypothesis works reasonably well to describe the height of the polymer brush and the density of monomers at the grafting surface. We also investigated the density profile of the free chain ends for different values of the radius of the spherical interface, different chain lengths, and different surface coverages. Self-consistent-field theory suggests the existence of an exclusion zone near the surface from which the chain ends are expelled. We do not observe a definite exclusion zone for most of the values of chain length, radius, and surface coverage studied here. However, some evidence of an exclusion zone is found in one case with high surface coverage.