Chemical potentials of chain solutes in hard body fluids

Abstract

Abstract Monte Carlo simulations and analytical statistical mechanical expressions are used to predict the free energy required to dissolve hard chains containing up to ten beads in diatomic fluids, over a wide range of solute-solvent sphere diameter ratios and solvent densities. The results are compared with analytical expressions derived from the Bonded Hard Sphere (BHS) and Scaled Particle Theory (SPT) mixed hard body fluid equations of state. Although both theoretical expressions agree very well with simulation results at lower densities, BHS predictions are found to better agree with simulation results at high densities (particularly for small solute particles). Both the simulation and theoretical results imply a strictly linear dependence of solute cavity formation free energy on chain length, in a solvent of a given molecular size and density. The results are used to quantify the influence of both solute and solvent shape on solute cavity formation free energy.