Department of Physics, Tohoku University, 980-8578 Sendai, Japan.
J Chem Phys. 2012 Jul 14;137(2):024904. doi: 10.1063/1.4733462.
We simulate structural phase behavior of polymer-grafted colloidal particles by molecular Monte Carlo technique. The interparticle potential, which has a finite repulsive square-step outside a rigid core of the colloid, was previously confirmed via numerical self-consistent field calculation. This model potential is purely repulsive. We simulate these model colloids in the canonical ensemble in two and three dimensions and find that these particles containing no interparticle attraction self-assemble and align in a string-like assembly, at low temperature and high density. This string-like colloidal assembly is related to percolation phenomena. Analyzing the cluster size distribution and the average string length, we build phase diagrams and discover that the average string length diverges around the region where the melting transition line and the percolation transition line cross. This result is similar to Ising spin systems, in which the percolation transition line and the order-disorder line meet at a critical point.
我们通过分子蒙特卡罗技术模拟了聚合物接枝胶体粒子的结构相行为。粒子间的相互作用势具有有限的排斥方步，在胶体的刚性核心之外，先前通过数值自洽场计算得到了验证。这个模型势是完全排斥的。我们在二维和三维的正则系综中模拟这些模型胶体，发现这些没有粒子间吸引力的粒子在低温和高密度下自组装并排列成串状组装。这种串状胶体组装与渗流现象有关。通过分析团簇大小分布和平均串长，我们构建了相图，并发现平均串长在熔融转变线和渗流转变线交叉的区域附近发散。这一结果类似于伊辛自旋系统，其中渗流转变线和有序无序转变线在临界点相遇。
