Packing entropy in micelle self-assembly

Results are presented from simulations of a lattice model which exhibits the self-assembly of micelles and a well-defined critical micelle concentration. It is possible, unambiguously, to extract the entropy associated with packing the chains into a micelle and to demonstrate that micellisation arises from a competition between the enthalpy and the packing entropy of the cluster. The effect of changing the length of the amphiphile head is reported and it is found that the loss of entropic freedom of the headgroups controls the position of the cmc.