Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra,Università degli Studi di Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy.
School of Chemistry and Physics, University of Kwazulu-Natal, Private Bag X01, Scottsville 3209, Pietermaritzburg, South Africa.
J Chem Phys. 2017 Oct 14;147(14):144902. doi: 10.1063/1.4995549.
The emergence of supramolecular aggregates from simple microscopic interaction rules is a fascinating feature of complex fluids which, besides its fundamental interest, has potential applications in many areas, from biological self-assembly to smart material design. We here investigate by Monte Carlo simulation the equilibrium structure of a two-dimensional mixture of asymmetric dimers and spheres (disks). Dimers and disks are hard particles, with an additional short-range attraction between a disk and the smaller monomer of a dimer. The model parameters and thermodynamic conditions probed are typical of colloidal fluid mixtures. In spite of the minimalistic character of the interaction, we observe-upon varying the relative concentration and size of the two colloidal species-a rich inventory of mesoscale structures at low temperature, such as clusters, lamellæ (i.e., polymer-like chains), and gel-like networks. For colloidal species of similar size and near equimolar concentrations, a dilute fluid of clusters gives way to floating lamellæ upon cooling; at higher densities, the lamellæ percolate through the simulation box, giving rise to an extended network. A crystal-vapour phase-separation may occur for a mixture of dimers and much larger disks. Finally, when the fluid is brought in contact with a planar wall, further structures are obtained at the interface, from layers to branched patterns, depending on the nature of wall-particle interactions.
从简单的微观相互作用规则中出现的超分子聚集体是复杂流体的一个迷人特征，除了其基本兴趣之外，它在许多领域都有潜在的应用，从生物自组装到智能材料设计。我们通过蒙特卡罗模拟研究了二维不对称二聚体和球体（圆盘）混合物的平衡结构。二聚体和圆盘是硬粒子，在圆盘和二聚体的较小单体之间存在额外的短程吸引力。所研究的模型参数和热力学条件是胶体流体混合物的典型条件。尽管相互作用具有最小化的特征，但我们观察到-在改变两种胶体物质的相对浓度和尺寸时-在低温下存在丰富的介观结构库存，例如簇、层片（即聚合物样链）和凝胶状网络。对于大小相似且接近等摩尔浓度的胶体物质，在冷却时，稀有的簇流体将转变为浮动层片；在更高的密度下，层片会渗透到模拟盒中，从而产生扩展的网络。对于二聚体和大得多的圆盘的混合物，可能会发生晶体-蒸气分相。最后，当将流体与平面壁接触时，根据壁-粒子相互作用的性质，在界面处获得进一步的结构，从层到分支图案。
