Conformation of Chains in Cores of Block Copolymer Micelles with Solubilized Homopolymer: a Monte Carlo Study

Abstract

A system of compatible self-avoiding polymer chains solubilized in spherical cores of block copolymer micelles was studied by lattice Monte Carlo simultions. The core is modeled as a spherical cavity on a simple cubic lattice, filled in partially by tethered (core-forming) chains and partially by free (solubilized) chains. Molecular parameters (e.g., the ratio of the contour length of the model chains to the core radius) correspond to those in real micellar systems. The density (the fraction of lattice sites occupied) is 0.6 which corresponds to swollen micellar cores in real micellar systems. Simulations yield a constant segment density profile in the core. Both the tethered and solubilized chains acquire an ellipsoidal shape. The ellipsoids equivalent to both types of chains are more spherical than those in a melt and strongly oriented. The chains in the core show a Gaussian-like behavior. Minor deviations from Gaussian behavior for tethered chains are due to surface effects.