On the self-consistent field theory of surfactant micelles

Abstract

Detailed molecular modelling of surfactant micelles is, in spite of enormous efforts during the last decade, still a formidable task. Exact description by molecular dynamics is, for the time being, computationally not feasible. Recently, we developed a self-consistent field theory to describe the self-assembly of surfactants into micelles, in which we used a Markov approximation for the chain statistics on a lattice with a spherical geometry. In this paper we extend our previous work by using a more exact anisotropic excluded-volume term in combination with a rotational isomeric state scheme in the chain statistics (referred to as the self-consistent anisotropic field (SCAF) theory). One of the most remarkable new results of our SCAF analysis is that the tails in the micelle are not “melt” like; the amount of order in the micelle is higher on the outer part of the core and lower in the micelle centre. The inefficient packing in the central part of the micelle has the effect that the tail density is locally reduced as compared to the outer region of the core.