Self Assembly of Bilayers in a Lattice Model of Amphiphile and Solvent Systems

The results of a Metropolis Monte Carlo simulation of a three dimensional lattice model of an amphiphile and solvent mixture are presented. In the model each amphiphile molecule is represented as a connected chain of lattice sites with one site representing the head and the remaining chain sites representing the tail of the molecule. The remaining sites on the lattice represent solvent molecules. The amphiphiles interact through a nearest neighbour potential which includes head-solvent and tail-solvent interactions. No prior assumption is made about the structures which may be observed.

The cluster size distribution and cluster structure is studied as a function of temperature and head-solvent interaction. If the tail-solvent interaction is solvophobic and the head-solvent interaction is solvophilic, a micellar region is observed in the phase diagram. For sufficiently solvophilic head-solvent interactions the low temperature phase exhibits self assembly into castellated bilayer structures.