(473g) Formation of Lamellar Structures from Spherical Particles

We report disorder to lamellar transitions in a system of spherical particles that invoke a short-range attraction and a long-range repulsion. The system provides a simplified model for aqueous dispersions of colloidal particles and globular proteins that may exhibit stable/metastable clusters or microscopic phases. We show that under appropriate conditions, a lamellar phase with alternating condensed and dilute layers of particles is thermodynamically more stable in comparison to a uniform disordered phase and the macroscopic fluid-fluid coexistence can be inhibited by formation of the lamellar structure. While the width of the condensed layers increases with the particle density, the trend is opposite for the dilute layers. A minimal lamellar thickness is obtained when the condensed and dilute layers approximately have the same width.