1 research outputs found
Probing the Structure and Dynamics of Confined Water in AOT Reverse Micelles
Reverse
micelles are attractive nanoscale systems used for the confinement
of molecules in studies of structure and chemical reactions, including
protein folding, and aggregation. The simulation of reverse micelles,
in which a water “pool” is separated from a nonpolar
bulk phase by a surfactant layer, poses significant challenges to
empirical force fields due to the diversity of interactions between
nonpolar, polar, and charged groups. We have explored the dependence
of system density, reverse micelle structure, and water configurational
relaxation times as a function of reverse micelle composition, including
water:surfactant ratio, absolute number of water molecules, and force
field using molecular dynamics simulations. The resulting structures
and dynamics are found to depend more on the force field used than
on varying interpretations of the water:surfactant ratio in terms
of absolute size of the reverse micelle. Substantial deviations from
spherical reverse micelle geometries are observed in all unrestrained
simulations. Rotational anisotropy decay times and water residence
times show a strong dependence on force field and water model used,
but power-law relaxation in time is observed independent of the force
field. Our results suggest the need for further experimental study
of reverse micelles that can provide insight into the distribution
and dynamics of shape fluctuations in these complex systems