The role of geometric constraints in amphiphilic self-assembly: A Brownian dynamics study

We use a stochastic molecular dynamics simulation method to investigate the effect of optimal head group area in amphiphilic self-assembly. For a fixed tail geometry, we choose several sizes of the effective head group area and carry out a detailed study of how this affects the critical micelle concentration (CMC), the cluster distribution, and the shape of micelles for different concentrations and temperature. We find that with an increase of the effective head group area, the CMC is attained at a larger concentration of the free chains at all temperatures. Likewise, for a given concentration, amphiphiles with the larger effective head group exhibit a sharper cluster distribution with a tendency to form more spherical micelles. Our study shows a way to control the size and shape of the micelles and can have potential impact on the synthesis of nano-structures through surfactant mediated templating methods.(C) 2003 American Institute of Physics.