Martin Fisher School of Physics, Brandeis University, Waltham, MA, USA.
Soft Matter. 2016 Nov 9;12(44):8990-8998. doi: 10.1039/c6sm01498d.
We use computer simulations and simple theoretical models to analyze the morphologies that result when rod-like particles end-attach onto a curved surface, creating a finite-thickness monolayer aligned with the surface normal. This geometry leads to two forms of frustration, one associated with the incompatibility of hexagonal order on surfaces with Gaussian curvature, and the second reflecting the deformation of a layer with finite thickness on a surface with non-zero mean curvature. We show that the latter effect leads to a faceting mechanism. Above threshold values of inter-particle attraction strength and surface mean curvature, the adsorbed layer undergoes a transition from orientational disorder to an ordered state that is demarcated by reproducible patterns of line defects. The number of facets is controlled by the competition between line defect energy and intra-facet strain. Tuning control parameters thus leads to a rich variety of morphologies, including icosahedral particles and irregular polyhedra. In addition to suggesting a new strategy for the synthesis of aspherical particles with tunable symmetries, our results may shed light on recent experiments in which rod-like HIV GAG proteins assemble around nanoscale particles.
我们使用计算机模拟和简单的理论模型来分析棒状颗粒末端附着在曲面上时形成的形态，从而形成与表面法向一致的有限厚度单层。这种几何形状导致了两种形式的挫折，一种与高斯曲率表面上的六方有序不相容有关，另一种反映了具有非零平均曲率的表面上有限厚度层的变形。我们表明，后一种效应导致了分形机制。在颗粒间吸引力强度和表面平均曲率的阈值以上，吸附层从取向无序转变为有序状态，由线缺陷的可重复图案来标记。面的数量由线缺陷能量和内层面内应变之间的竞争来控制。因此，调节控制参数可以产生丰富多样的形态，包括二十面体颗粒和不规则多面体。除了为具有可调谐对称性的非球型颗粒的合成提出新的策略外，我们的结果还可能揭示最近的实验，其中棒状 HIV GAG 蛋白围绕纳米级颗粒组装。
