MOLECULAR-DYNAMICS STUDY OF A HYDROPHOBIC AGGREGATE IN AN AQUEOUS-SOLUTION OF METHANE

A solution of methane-like particles in liquid water is found to form a hydrocarbon assembly with a cylindrical shape under certain conditions. Earlier studies of the potential of mean force between two methane particles in aqueous solutions have never revealed any tendency for hydrophobic aggregation. Thus, the system studied here, consisting of 18 Lennard-Jones particles and 107 water molecules, confirms the importance of many-body effects in hydrophobic assemblies. Properties of the solution, evaluated with respect to the cylindrical hydrocarbon core, indicate only minor perturbances of the interfacial water relative to the bulk water. High-pressure simulations of the same system exhibit contrary behavior, with a strong hydration formation preventing the aggregation of methane particles. Definite clathrate structures present solvate monomer, dimer, or trimer methane clusters.