Enthalpy and entropy of transfer of alkanes from water phase to the micelle core

Abstract

Enthalpy and entropy of transfer from water phase to a sodium dodecyl sulphate (SDS) micelle core and , respectively, have been investigated by molecular dynamics calculation for a series of hydrophobic solutes originally immiscible with water. It is found that both thermodynamic quantities decrease as a function of number of carbon atoms of the alkanes. Structural behaviour of the solubilised alkane molecules in the micelle has been analysed too. The calculated distribution functions show that methane moves around the whole core, whereas the alkane molecules larger than methane are localised in the centre of the core, i.e. the low-density region of the alkyl chains of SDS.