Howard Michael P, Sherman Zachary M, Milliron Delia J, Truskett Thomas M
McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA.
J Chem Phys. 2021 Jan 14;154(2):024905. doi: 10.1063/5.0033413.
We extend Wertheim's thermodynamic perturbation theory to derive the association free energy of a multicomponent mixture for which double bonds can form between any two pairs of the molecules' arbitrary number of bonding sites. This generalization reduces in limiting cases to prior theories that restrict double bonding to at most one pair of sites per molecule. We apply the new theory to an associating mixture of colloidal particles ("colloids") and flexible chain molecules ("linkers"). The linkers have two functional end groups, each of which may bond to one of several sites on the colloids. Due to their flexibility, a significant fraction of linkers can "loop" with both ends bonding to sites on the same colloid instead of bridging sites on different colloids. We use the theory to show that the fraction of linkers in loops depends sensitively on the linker end-to-end distance relative to the colloid bonding-site distance, which suggests strategies for mitigating the loop formation that may otherwise hinder linker-mediated colloidal assembly.
我们扩展了韦特海姆的热力学微扰理论，以推导多组分混合物的缔合自由能，该混合物中任意两个分子的任意数量键合位点之间都能形成双键。在极限情况下，这种推广可简化为先前的理论，即每个分子最多限制有一对位点形成双键。我们将新理论应用于胶体颗粒（“胶体”）和柔性链分子（“连接体”）的缔合混合物。连接体有两个官能端基，每个端基都可以与胶体上的几个位点之一键合。由于其柔性，相当一部分连接体可以“成环”，两端都与同一胶体上的位点键合，而不是桥接不同胶体上的位点。我们用该理论表明，成环连接体的比例敏感地取决于连接体的端到端距离与胶体键合位点距离的相对关系，这为减轻可能阻碍连接体介导的胶体组装的成环现象提供了策略。
