Conformations of Insoluble Blocks in Swollen Micellar Cores of Multimolecular Block Copolymer Micelles Studied by Monte Carlo Simulation Technique

Abstract

Monte Carlo simulations of chain conformations in restricted spherical volumes with an increasing radius were performed on a tetrahedral lattice (ca 2 700 to 9 200 lattice sites) at relatively high densities of the occupied lattice sites. A simultaneous self-avoiding walk together with the equilibration algorithm similar to that of Siepmann and Frenkel were used to create the equilibrated multi-chain conformations. (a) A series of simulations was carried out for a constant average segment density, <gS> = 0.52, together with the three values of the radius of the sphere, R = 10 l, 12.5 l and 15 l (l is the lattice distance), and various numbers of chains, N ∈ <15, 86>, and chain lengths, L ∈ <31, 163>. The results give information on the system behavior and on the effects of: (i) multi-chain conformational correlations, which depend both on N and L, (ii) the L-dependent chain flexibility, and (iii) R-dependent external geometrical constraints. Another two series of data: (b) for a constant average segment density, <gS> = 0.36, a constant N = 21, and L proportional to R3, and (c) for <gS> = 0.36, L = 47 and N proportional to R3, are shown to give a supplementary detailed information on conformational behavior of individual chains. Various physical quantities (e.g. the densities of chain free ends, gF(r), or distributions of the tethered end-to-the free end distances, ρTF(rTF), etc.) were calculated in the course of computer simulations and their shapes and physical significance is discussed with respect to the changing values of N, L and R.