Zhu Yiwei, Chapman Walter G
Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA.
J Chem Phys. 2021 Apr 7;154(13):134901. doi: 10.1063/5.0039287.
Patchy colloids can be modeled as hard spheres with directional conical association sites. A variety of physical phenomena have been discovered in the patchy colloid system due to its short range and directional interactions. In this work, we combined a cluster distribution theory with generalized Flory and Stockmayer percolation theory to investigate the interplay between phase behavior and percolation for a binary patchy colloid system. The binary patchy colloid system consists of solute molecules with spherically symmetric bonding sites and solvents with two singly bondable sites. Wertheim's first order thermodynamic perturbation theory (TPT1) has been widely applied to the patchy colloids system and it has been combined with percolation theory to study the percolation threshold. However, due to assumptions behind TPT1, it will lose accuracy for a system in which particles have multiple association sites or multiply bondable sites. A recently proposed cluster distribution theory accurately models association at sites that can form multiple bonds. In this work, we investigate the comparison among cluster distribution theory, TPT1, and Monte Carlo simulation for the bonding states of this binary system in which cluster distribution theory shows excellent agreement with Monte Carlo simulation, while TPT1 has a large deviation with the simulation. Cluster distribution theory was further combined with the Flory and Stockmayer percolation theory to investigate the interplay between phase behavior and percolation threshold. We found that the reduced density and the relative bonding strength of solvent-solvent association and solute-solvent association are key factors for the phase behavior and percolation. Percolation can form at low density and low temperature in the vapor phase of this binary system, where the star-like molecules with 12 long branches formed.
斑块状胶体可以被建模为具有定向锥形缔合位点的硬球。由于其短程和定向相互作用，在斑块状胶体系统中发现了各种物理现象。在这项工作中，我们将团簇分布理论与广义弗洛里和斯托克迈耶渗流理论相结合，以研究二元斑块状胶体系统的相行为和渗流之间的相互作用。二元斑块状胶体系统由具有球对称键合位点的溶质分子和具有两个可单键合位点的溶剂组成。韦特海姆一阶热力学微扰理论（TPT1）已被广泛应用于斑块状胶体系统，并已与渗流理论相结合来研究渗流阈值。然而，由于TPT1背后的假设，对于粒子具有多个缔合位点或可多重键合位点的系统，它将失去准确性。最近提出的团簇分布理论准确地模拟了可以形成多个键的位点处的缔合。在这项工作中，我们研究了团簇分布理论、TPT1和蒙特卡罗模拟在该二元系统键合状态方面的比较，其中团簇分布理论与蒙特卡罗模拟显示出极好的一致性，而TPT1与模拟有很大偏差。团簇分布理论进一步与弗洛里和斯托克迈耶渗流理论相结合，以研究相行为和渗流阈值之间的相互作用。我们发现，溶剂 - 溶剂缔合和溶质 - 溶剂缔合的折合密度和相对键合强度是相行为和渗流的关键因素。在该二元系统的气相中，在低密度和低温下可以形成渗流，在那里形成了具有12个长分支的星状分子。
