Computer Simulations Of Micelle Fission And Self-assembly Of Bola Surfactants

In this work, we study the fission process of large micelles using dissipative particle dynamics (DPD). In the simulations of micelles fission, we prepared a large micelle as the initial configuration self-assembled of H4T3 surfactants for further fission and changed the head-head repulsive interaction to stronger values. We got the average time evolutions of the Minkowski functional, including volume, surface area, integral mean curvature, and Euler characteristic for a typical micelle fission process. We find out the effects of head-head interaction during the fission process and there exist four different stages during a fission process in general. Then we simulated another micelles fission aggregated of H4T4 with two different shapes to study the effects of tail size in fission dynamics. The simulation results demonstrated that the first, second and third stages are characterized with distinct dynamic features, depending on the surfactant architecture. It is found that surfactants architecture controls the micelle fission process, especially for the second stage, similar to the way it controls the size and shape of the aggregates at equilibrium. Since for most case it is the second stage dominating the lifetime of a micelle, we suggest that the molecule packing parameter is not only a predictor of the shape and size of aggregates, but also a predictor of kinetic properties for micelle fission.Additionally, we studied a special surfactant-Bola surfactant, which has two hydrophilic heads while the traditional surfactant has only one head. We investigated the self-assembly mechanism of Bola surfactants with different size of hydrophilic heads and different hydrophobic tails, using DPD simulation. Different morphologies of self-assembly Bola surfactants were observed, depending on the structure characterization of Bola surfactants. Based on the packing parameter, a quantitative model was developed here to the simulation result. In general, the mechanism of self-assembly for Bola surfactants process can be interpreted from the qualitative model.