Conformation of a polymer chain in explicit solvent: A solvation potential approach

Abstract

AbstractIn much of the theoretical work on polymers in dilute solution the effects of solvent are treated in an implicit fashion: thus one studies an isolated chain interacting via an effective site–site potential. Although a formally exact mapping is possible between the chain‐in‐solvent system and a corresponding isolated effective‐potential‐chain, this mapping involves a many‐site solvation potential which is not practical to compute. Thus, one generally resorts to a two‐site potential approximation. In this article we test the validity of this two‐site approximation for a short hard‐sphere (HS) n‐mer chain (n ≤ 5) in a HS solvent. This test involves computing a set of “exact” site–site solvation potentials for an isolated chain. These potentials are shown to reproduce the conformation of a chain in explicit solvent. We make use of these exact short‐chain results (combining them with the solvent potential of mean force) to construct approximate two‐site solvation potentials for long chains. Monte Carlo simulations have been performed for HS chain‐in‐solvent systems and for the corresponding isolated effective‐potential n‐mer chain with n ≤ 50. These simulations show that our solvation potentials provide a quantitatively accurate description of the conformation of a HS chain in explicit (hard sphere) solvent. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3319–3326, 2007