Spherical brushes within spherical cavities: A self-consistent field and Monte Carlo study

Abstract

8 pages, 8 figures.We present an extensive numerical study on the behavior of spherical brushes confined into a spherical cavity. Self-consistent field (SCF) and off-lattice Monte Carlo (MC) techniques are used in order to determine the monomer and end-chain density profiles and the cavity pressure as a function of the brush properties. A comparison of the results obtained via SCF, MC, and the Flory theory for polymer solutions reveals SCF calculations to be a valuable alternative to MC simulations in the case of free and softly compressed brushes, while the Flory’s theory accounts remarkably well for the pressure in the strongly compressed regime. In the range of high compressions, we have found the cavity pressure P to follow a scale relationship with the monomer volume fraction v, P ∼ vα. SCF calculations give α = 2.15±0.05, whereas MC simulations lead to α = 2.73±0.04. The underestimation of α by the SCF method is explained in terms of the inappropriate account of the monomer density correlations when a mean field approach is used.Financial support from MCyT (Spain) and FEDER(EU)(Grant No. FIS2007-60327) is acknowledged. J.J.C. also wants to thank the financial support of MEC (Spain), postdoctoral grant (Grant No. EXP2006-0931).Peer reviewe