Particle ordering at the initial stage of colloidal crystallization: implication for non-classical dynamic behavior

Abstract

The particle ordering dynamics of polystyrene colloids were studied using low-angle laser light scattering and Brownian dynamics (BD) simulation. The polystyrene particles were prepared in the highly deionized water and crystalline states were realized after shear melting due to vigorous circulation of fluids. The radius of gyration of crystalline clusters was evaluated by the laser light scattering and showed the rapid increase of cluster size similar to percolation dynamics with increasing crystalline fraction. The following dynamics were confirmed by BD simulation. The ordered domains were formed under the repulsive potential of latex particles and extended to all over the sample within a relatively short time. The domains were connected as in percolation transitions at a critical threshold. This means that the critical clusters are not compact as in the final crystal but form a rather loose structure in the nucleation stage of colloidal crystallization. The consistent results between experiments and simulation indicate a new ordering dynamics from metastable liquid, which is quite different from the standard nucleation minimizing the free energy of critical nucleus.