Are Micelles Needed to Form Methane Hydrates in Sodium Dodecyl Sulfate Solutions?

The possibility that methane hydrates form in sodium dodecyl sulfate (SDS) water solutions without the help of micelles formation has been investigated. To asses whether micelles are needed for the hydrate to form only one SDS molecule has been considered. To figure out the possible mechanism through which the SDS promotes the formation of methane clathrate the dynamics of CH4 solvation in the presence and absence of the surfactant molecule is monitored. To carry out the dynamical calculations, the SDS-H2O, SDSCH4, and CH4-H2O interactions were described using a recently proposed model potential. The adopted model leverages both on the decomposition of the molecular polarizability in effective components associated with the interaction centers distributed on the molecular frame and on the use of an improved Lennard-Jones functional form to represent the effective pair interaction energies. Molecular dynamics simulations performed on such potential, contrary to some earlier assumptions, do not support mechanisms requiring the formation of micelles as suggested by the findings of more recent experiments.