Effect of long-range and steric hydrophilic interactions on micellization of surfactant solutions: A Monte Carlo study in 2-D

Monte Carlo simulations of aqueous surfactant solutions have been performed on a two-dimensional lattice in a canonical ensemble. The simulations are based on four different models of surfactants with chainlike geometry and several types of interactions between the surfactant headgroups. The effect of number of headgroups (N_HG) and the types of interactions between them (short-range versus long-range) has been examined on the surfactant aggregation. The simulations show that the aqueous solutions of surfactant chains with N_HG > 1 and a short-range head-head interactions behave in a manner similar to that of the solutions of surfactant chains with N_HG = 1 and long-range electrostatic interactions between the headgroups. The similarity of the results in the two models is discussed on the basis of free energy of micellization and is shown to be an effect of similar excluded volume of headgroups in the two models.