Grosberg Alexander Y, Rabin Yitzhak
Department of Physics and Center for Soft Matter Research, New York University, 726 Broadway, New York, NY 10003, USA.
Soft Matter. 2020 Aug 21;16(31):7414-7420. doi: 10.1039/d0sm00893a. Epub 2020 Jul 23.
Spherical colloids that catalyze the interconversion reaction A⇋B between solute molecules A and B whose concentration at infinity is maintained away from equilibrium effectively interact due to the non-uniform fields of solute concentrations. We show that this long range 1/r interaction is suppressed via a mechanism that is superficially reminiscent but qualitatively very different from electrostatic screening: catalytic activity drives the concentrations of solute molecules towards their equilibrium values and reduces the chemical imbalance that drives the interaction between the colloids. The imposed non-equilibrium boundary conditions give rise to a variety of geometry-dependent scenarios; while long-range interactions are suppressed (except for a finite penetration depth) in the bulk of the colloid solution in 3D, they can persist in quasi-2D geometry in which the colloids but not the solutes are confined to a surface, resulting in the formation of clusters or Wigner crystals, depending on the sign of the interaction between colloids.
球形胶体催化溶质分子A和B之间的互变反应A⇋B，溶质分子A和B在无穷远处的浓度保持远离平衡状态，由于溶质浓度的非均匀场，它们会有效地相互作用。我们表明，这种长程1/r相互作用通过一种机制被抑制，这种机制表面上让人联想到静电屏蔽，但在性质上却有很大不同：催化活性使溶质分子的浓度趋向于其平衡值，并减少了驱动胶体间相互作用的化学不平衡。施加的非平衡边界条件会产生各种与几何形状有关的情况；虽然在三维胶体溶液的主体中长程相互作用被抑制（除了有限的穿透深度），但在准二维几何结构中它们可能会持续存在，在这种结构中胶体而非溶质被限制在一个表面上，根据胶体间相互作用的符号，会导致形成团簇或维格纳晶体。
