title: A molecular dynamics study of free energy of micelle formation for sodium dodecyl sulfate in water and its size distribution.
abstract: Free energy of micelle formation has been evaluated for spherical sodium dodecyl sulfate (SDS) in water by a thermodynamic integration method combined with a series of large-scale molecular dynamics calculations following the chemical species model. In particular, free energy change delta mu(n+1)0 with respect to the addition of one surfactant molecule to the spherical micelle of size n was obtained as a function of n. The free energy profile showed a minimum followed by a maximum, which corresponds to a peak in the size distribution. The calculated peak size n = 57 near its critical micelle concentration is in good agreement with the experimental averaged aggregation number n = 55-75 of the SDS micelle. The distribution showed a rather sharp peak, indicating that the size is almost a monodisperse one. The size is likely to be insensitive to the total concentration of the surfactant.
authors.affiliation: Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Yoshii
authors.forename: Kensuke
authors.initials: K
authors.lastname: Iwahashi
authors.forename: Susumu
authors.initials: S
authors.lastname: Okazaki
mesh_terms: D000465:Algorithms; D004735:Energy Transfer; D008823:Micelles; D010316:Particle Size; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D008823:Micelles; D013501:Surface-Active Agents; D014867:Water; D012967:Sodium Dodecyl Sulfate