Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106-5080, USA.
Phys Rev E. 2019 Nov;100(5-1):052603. doi: 10.1103/PhysRevE.100.052603.
Soluto-inertial (SI) suspension interactions allow colloidal particles to be driven large distances over sustained periods of time. These interactions involve soluto-inertial "beacons" that establish and maintain solute fluxes over long times by slowly absorbing or emitting solutes in response to changes in the surrounding solution. Suspended particles then migrate in response to solute fluxes via diffusiophoresis (DP). Beacon materials must be chosen to maintain these solute fluxes, with range and duration in mind. Here we present a general strategy to facilitate qualitative design and quantitative prediction of SI interactions for a given beacon-solute pair. Specifically, we look at two classes of SI beacons: those that partition solute and those that associate with solute. We identify the design parameters for these systems to construct a parameter space map, calculate characteristic timescales over which SI fluxes persist, and generate approximate analytical expressions for solute concentration profiles. Further, we use these expressions to predict the DP velocity of colloids interacting with beacons, noting qualitative differences between beacon sources that release solute and beacon sinks that absorb solute. Proof-of-principle experiments of beacon sources and sinks, of partitioning, and associating types highlight the basic findings. More broadly, the conceptual approach outlined here can be adapted to treat SI interactions mediated by other materials such as dissolving solids, gases, evaporating liquids, ion-exchange resins, and others.
固溶惰性（SI）悬浮相互作用允许胶体颗粒在持续的时间内被驱动到很远的距离。这些相互作用涉及固溶惰性“信标”，它们通过缓慢吸收或释放溶质来响应周围溶液的变化，从而建立和维持长时间的溶质通量。然后，悬浮颗粒通过扩散泳（DP）响应溶质通量迁移。必须选择信标材料来维持这些溶质通量，同时考虑范围和持续时间。在这里，我们提出了一种通用策略，以方便定性设计和定量预测给定信标-溶质对的 SI 相互作用。具体来说，我们研究了两类 SI 信标：那些分配溶质的信标和那些与溶质结合的信标。我们确定了这些系统的设计参数，以构建参数空间图，计算 SI 通量持续的特征时间，并生成溶质浓度分布的近似解析表达式。此外，我们使用这些表达式来预测与信标相互作用的胶体的 DP 速度，并注意到释放溶质的信标源和吸收溶质的信标汇之间的定性差异。分区和关联类型的信标源和汇的原理验证实验突出了基本发现。更广泛地说，这里概述的概念方法可以适用于处理由其他材料介导的 SI 相互作用，例如溶解固体、气体、蒸发液体、离子交换树脂等。
