de Los Santos-López Néstor M, Pérez-Ángel Gabriel, Méndez-Alcaraz José M, Castañeda-Priego Ramón
Departamento de Física Aplicada, Cinvestav-Mérida, AP 73 "Cordemex," 97310 Mérida, Yucatán, Mexico.
Departamento de Física, Cinvestav, Av. IPN 2508, Col. San Pedro Zacatenco, Gustavo A. Madero, 07360 Ciudad de México, Mexico.
J Chem Phys. 2021 Jul 14;155(2):024901. doi: 10.1063/5.0052369.
Depletion interactions between colloidal particles surrounded by smaller depletants are typically characterized by a strong attraction at contact and a moderately repulsive barrier in front of it that extends at distances similar to the size of the depletants; the appearance and height of the barrier basically depend on the concentration and, therefore, the correlation between depletants. From a thermodynamic point of view, the former can drive the system to phase separation or toward non-equilibrium states, such as gel-like states, but its effects on both local and global properties may be controlled by the latter, which acts as a kind of entropic gate. However, the latter has not been entirely analyzed and understood within the context of colloidal mixtures mainly driven by entropy. In this contribution, we present a systematic study of depletion forces in ternary mixtures of hard spherical particles with two species of depletants, in two and three dimensions. We focus the discussion on how the composition of the depletants becomes the main physical parameter that drives the competition between the attractive well and the repulsive barrier. Our results are obtained by means of the integral equation theory of depletion forces and techniques of contraction of the description adapted to molecular dynamics computer simulations.
被较小的耗尽剂包围的胶体颗粒之间的耗尽相互作用通常表现为接触时的强吸引力以及在其前方延伸出与耗尽剂尺寸相似距离的适度排斥势垒；势垒的出现和高度基本上取决于浓度，因此取决于耗尽剂之间的相关性。从热力学角度来看，前者可驱动系统发生相分离或趋向非平衡态，如凝胶态，但它对局部和全局性质的影响可能由后者控制，后者起到一种熵门的作用。然而，在主要由熵驱动的胶体混合物背景下，对后者尚未进行全面分析和理解。在本论文中，我们对二维和三维中含有两种耗尽剂的硬球形颗粒三元混合物中的耗尽力进行了系统研究。我们将讨论重点放在耗尽剂的组成如何成为驱动吸引阱和排斥势垒之间竞争的主要物理参数上。我们的结果是通过耗尽力的积分方程理论以及适用于分子动力学计算机模拟的描述收缩技术得到的。
