title: Parameterization of a mesoscopic model for the self-assembly of linear sodium alkyl sulfates.
abstract: A systematic approach to develop mesoscopic models for a series of linear anionic surfactants (CH3(CH2)n - 1OSO3Na, n = 6, 9, 12, 15) by dissipative particle dynamics (DPD) simulations is presented in this work. The four surfactants are represented by coarse-grained models composed of the same head group and different numbers of identical tail beads. The transferability of the DPD model over different surfactant systems is carefully checked by adjusting the repulsive interaction parameters and the rigidity of surfactant molecules, in order to reproduce key equilibrium properties of the aqueous micellar solutions observed experimentally, including critical micelle concentration (CMC) and average micelle aggregation number (Nag). We find that the chain length is a good index to optimize the parameters and evaluate the transferability of the DPD model. Our models qualitatively reproduce the essential properties of these surfactant analogues with a set of best-fit parameters. It is observed that the logarithm of the CMC value decreases linearly with the surfactant chain length, in agreement with Klevens' rule. With the best-fit and transferable set of parameters, we have been able to calculate the free energy contribution to micelle formation per methylene unit of -1.7 kJ/mol, very close to the experimentally reported value.
authors.affiliation: Laboratoire de Chimie-Physique, UMR 8000 CNRS, Université Paris-Sud, Orsay, France.
authors.forename: Zhaohuan
authors.initials: Z
authors.lastname: Mai
authors.affiliation: Laboratoire de Génie des Procédés et Matériaux, Ecole Centrale Paris, Grande Voie des Vignes, 92295 Châtenay-Malabry, France.
authors.forename: Estelle
authors.initials: E
authors.lastname: Couallier
authors.affiliation: Laboratoire de Génie des Procédés et Matériaux, Ecole Centrale Paris, Grande Voie des Vignes, 92295 Châtenay-Malabry, France.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Rakib
authors.affiliation: Laboratoire de Chimie-Physique, UMR 8000 CNRS, Université Paris-Sud, Orsay, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Rousseau