title: Simulations of micellization of sodium hexyl sulfate.
abstract: Micellization of the ionic surfactant sodium hexyl sulfate has been studied using atomistic explicit-solvent molecular dynamics simulations with and without excess NaCl or CaCl(2). Simulations were performed at surfactant loadings near the critical micellization concentration. Equilibrium micelle size distributions and estimates of the critical micellization concentration obtained from the simulations are in agreement with experimental data. In comparison to the sodium dodecyl sulfate surfactant, the shorter alkyl chain of sodium hexyl sulfate results in increased disorder of the micellar core and water exposure of the hydrocarbon tail groups. However, water and ions do not penetrate into the micellar core even for these weakly micellizing surfactants. Excess NaCl is observed to have a minor influence on the micelle structure but excess CaCl(2) induces drastic changes both in the structure and the dynamics of the micellar system. Furthermore, in the absence of excess salt, sodium hexyl sulfate forms predominantly spherical, disorganized aggregates but an increase in ionic strength drives an increase in aggregate size and leads to prolate aggregates.
authors.affiliation: Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut, USA.
authors.forename: M
authors.initials: M
authors.lastname: Sammalkorpi
authors.forename: S
authors.initials: S
authors.lastname: Sanders
authors.forename: A Z
authors.initials: AZ
authors.lastname: Panagiotopoulos
authors.forename: M
authors.initials: M
authors.lastname: Karttunen
authors.forename: M
authors.initials: M
authors.lastname: Haataja
mesh_terms: D002122:Calcium Chloride / Q000737:chemistry; D008823:Micelles; D056004:Molecular Dynamics Simulation; D009994:Osmolar Concentration; D012965:Sodium Chloride / Q000737:chemistry; D013463:Sulfuric Acid Esters / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D008823:Micelles; D013463:Sulfuric Acid Esters; D013501:Surface-Active Agents; C558488:sulfuric acid monohexyl ester; D012965:Sodium Chloride; D002122:Calcium Chloride