Computer simulation of micelle self-assembly.

Results are presented from a three dimensional lattice model of amphiphile-solvent and amphiphile-amphiphile-solvent systems studied using Monte Carlo simulations. This model builds upon previous models [1-11] allowing for a longer am-phiphilic head group and the inclusion of a second, different amphiphile. Detailed simulations are run using both a single amphiphile and double amphiphile model to study the self-assembly of micelles. Analysis of the results from these simulations shows that the models exhibit a critical micelle concentration together with cluster size distributions consistent with experiment and theory. Simulations of the single amphiphile model also give information on the free energy of micelle formation with the entropic and enthalpic contributions determined. It is found that the competition between the decreasing internal energy per monomer and entropy per monomer is the source of micellar behaviour. This result is then confirmed independently by calculating the partition function of an amphiphilic cluster using an extension to the Rosenbluth scheme [12-14]. Further results are also presented from simulations studying the effect of changing the head length, the hydrophilicity and the chain stiffness of the modelled am-phiphiles. Similar results for the internal energy and entropy are found concerning changes to the amphiphilic head group, however changes in amphiphilic chain stiffness highlight the importance of the structure of the micelle core.