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.
Université de Lorraine, LCP-A2MC, UR 3469, 1 Blvd. François Arago, Metz F-57078, France.
J Phys Chem B. 2022 Mar 10;126(9):2027-2039. doi: 10.1021/acs.jpcb.1c09758. Epub 2022 Feb 28.
Self-assembling complex fluids are often modeled as particles with effective competing isotropic interactions, combining a short-range attraction (SA) followed by a longer-range repulsion (LR). For moderately low temperatures and densities, SALR particles form clusters in equilibrium, at least provided that the potential parameters are appropriate. Here we inquire into the possibility that cluster formation in SALR fluids might be pushed by a foreign species even under thermodynamic conditions that would not allow for clusterization of the pure system. To this aim, we study by Monte Carlo simulations a mixture of hard-sphere two-Yukawa particles and hard spheres, with a cross interaction modeled by a square-well attraction, and we investigate the conditions of clustering in terms of strength of attraction and relative concentration of the two species. We find that clusters can occur in the mixture for the same temperature and density where the pure SALR fluid is almost structureless. In particular, we single out a cross attraction such that clusters are formed with a SALR concentration as low as 5%. We also find a situation where nearly pure droplets of hard spheres are held together by a shell of SALR particles. Conversely, we show that clustering can be undermined in the mixture under conditions for which this process takes place in the parent SALR fluid. Using a simple criterion, based on the second virial coefficients of the attractive part of interaction potentials (the so-called "reference attractive fluids"), we are able to predict accurately whether clustering is favored (or hindered) in the mixture, as compared to the pure SALR fluid.
自组装复杂流体通常被建模为具有有效竞争各向同性相互作用的粒子，结合短程吸引力（SA）和长程排斥力（LR）。对于中等低温度和密度，SALR 粒子在平衡时形成团簇，至少在合适的潜在参数下是这样。在这里，我们探讨了在热力学条件下，即使对于纯体系不会发生团簇化的情况下，外来物种是否可能推动 SALR 流体中的团簇形成。为此，我们通过蒙特卡罗模拟研究了硬球双 Yukawa 粒子和硬球的混合物，其中交叉相互作用由方阱吸引模拟，并根据吸引力强度和两种物质的相对浓度来研究团簇化的条件。我们发现，在相同温度和密度下，混合物中可能会出现团簇，而纯 SALR 流体几乎没有结构。特别是，我们确定了一种交叉吸引力，使得在 SALR 浓度低至 5%的情况下形成团簇。我们还发现了一种情况，即几乎纯的硬球液滴被 SALR 粒子壳层结合在一起。相反，我们表明，在这种过程发生在母体 SALR 流体的条件下，混合物中的团簇化可能会受到破坏。我们使用基于相互作用势能吸引力部分的第二维里系数的简单准则（所谓的“参考吸引力流体”），能够准确预测混合物中团簇化是否受到青睐（或阻碍），与纯 SALR 流体相比。
