Liu Fanghui, Zargarzadeh Leila, Chung Hyun-Joong, Elliott Janet A W
Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta, Canada T6G 1H9.
J Phys Chem B. 2017 Oct 12;121(40):9452-9462. doi: 10.1021/acs.jpcb.7b07271. Epub 2017 Sep 29.
Thermodynamic phase behavior is affected by curved interfaces in micro- and nanoscale systems. For example, capillary freezing point depression is associated with the pressure difference between the solid and liquid phases caused by interface curvature. In this study, the thermal, mechanical, and chemical equilibrium conditions are derived for binary solid-liquid equilibrium with a curved solid-liquid interface due to confinement in a capillary. This derivation shows the equivalence of the most general forms of the Gibbs-Thomson and Ostwald-Freundlich equations. As an example, the effect of curvature on solid-liquid equilibrium is explained quantitatively for the water/glycerol system. Considering the effect of a curved solid-liquid interface, a complete solid-liquid phase diagram is developed over a range of concentrations for the water/glycerol system (including the freezing of pure water or precipitation of pure glycerol depending on the concentration of the solution). This phase diagram is compared with the traditional phase diagram in which the assumption of a flat solid-liquid interface is made. We show the extent to which nanoscale interface curvature can affect the composition-dependent freezing and precipitating processes, as well as the change in the eutectic point temperature and concentration with interface curvature. Understanding the effect of curvature on solid-liquid equilibrium in nanoscale capillaries has applications in the food industry, soil science, cryobiology, nanoporous materials, and various nanoscience fields.
热力学相行为受微纳尺度系统中弯曲界面的影响。例如，毛细管凝固点降低与界面曲率引起的固液相之间的压力差有关。在本研究中，推导了由于毛细管限制而具有弯曲固液界面的二元固液平衡的热、力学和化学平衡条件。该推导表明了吉布斯 - 汤姆逊方程和奥斯特瓦尔德 - 弗伦德里希方程最一般形式的等价性。作为一个例子，定量解释了曲率对水/甘油体系固液平衡的影响。考虑弯曲固液界面的影响，绘制了水/甘油体系在一定浓度范围内的完整固液相图（根据溶液浓度，包括纯水的凝固或纯甘油的析出）。将该相图与假设固液界面为平面的传统相图进行了比较。我们展示了纳米尺度界面曲率对成分依赖的凝固和析出过程的影响程度，以及共晶点温度和浓度随界面曲率的变化。了解曲率对纳米尺度毛细管中固液平衡的影响在食品工业、土壤科学、低温生物学、纳米多孔材料以及各种纳米科学领域都有应用。
