Department of Physics, Kansas State University, Manhattan, Kansas 66503, USA.
J Chem Phys. 2009 Nov 21;131(19):194908. doi: 10.1063/1.3262311.
We present results from detailed three-dimensional Brownian dynamics simulations of the self-assembly process in quenched short-range attractive colloids. Clusters obtained in the simulations range from dense faceted crystals to fractal aggregates which show ramified morphology on large length scales but close-packed crystalline morphology on short length scales. For low volume fractions of the colloids, the morphology and crystal structure of a nucleating cluster are studied at various times after the quench. As the volume fraction of the colloids is increased, growth of clusters is controlled by cluster diffusion and cluster-cluster interactions. For shallower quenches and low volume fractions, clusters are compact and the growth-law exponent agrees well with Binder-Stauffer predictions and with recent experimental results. As the volume fraction is increased, clusters do not completely coalesce when they meet each other and the kinetics crosses over to diffusion-limited cluster-cluster aggregation (DLCA) limit. For deeper quenches, clusters are fractals even at low volume fractions and the growth kinetics asymptotically reaches the irreversible DLCA case.
我们呈现了在淬火短程吸引胶体中自组装过程的详细三维布朗动力学模拟结果。模拟中得到的团簇范围从密集的面心立方晶体到分形聚集体，它们在大尺度上表现出分支状形态，但在短尺度上表现出密堆积的晶体形态。对于胶体的低体积分数，在淬火后不同时间研究了成核团簇的形态和晶体结构。随着胶体体积分数的增加，团簇的生长受到团簇扩散和团簇-团簇相互作用的控制。对于较浅的淬火和低体积分数，团簇是紧密的，生长律指数与 Binder-Stauffer 预测值和最近的实验结果吻合较好。随着体积分数的增加，当团簇相遇时，它们不会完全聚结，动力学跨越到扩散限制的团簇-团簇聚集（DLCA）极限。对于更深的淬火，即使在低体积分数下，团簇也是分形的，生长动力学渐近达到不可逆的 DLCA 情况。
