Defect and Diffusion Forum Vols. 261-262

Abstract: In this paper we perform a systematic Monte Carlo study of the effective diffusivity in a 2D composite in which the dispersed phase (squares) is arranged in square planar and brick-work patterns within the matrix phase. We focus on the commonly encountered case where the dispersed phase has a much lower diffusivity than the matrix and where the segregation of the diffusant favours the matrix phase. It is found that while the generalized Maxwell-Garnett Equation generally describes the effective diffusivity semi-quantitatively, in order to have an accurate representation of the effective diffusivity at moderate volume fractions of the dispersed phase, it is necessary to use a more refined Maxwell-Garnett Equation that takes into account the actual shape and geometry of the dispersed phase.

Abstract: The distributions and transfer energies of several molecules and atomic groups between water and a structured hydrophobic phase were calculated by the molecular dynamics method. The coefficients of oxygen diffusion in a tetradecane membrane were estimated. The transfer energy of charged atomic groups was found to correlate with changes in the Born solvation energy. The contributions of atoms to the transfer energy of functional groups were shown to be non-additive. The steered dynamics method for estimating the kinetic parameters of the penetration of molecules through interphase boundaries was developed. Heterogeneous microviscosity of a membrane was calculated for a hydrated l-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine bilayer. Effects of the chemical properties of penetrant molecule on its translocation through the membrane were studied.