Nucleation and solidification in static arrays of monodisperse drops
Nucleation and solidification in static arrays of monodisperse drops
复制标题
DOI：
10.1039/b821785h
复制
发表时间：
2009-01-01
期刊：
影响因子：
6.1
通讯作者：
Toner, Mehmet
中科院分区：
文献类型：
--
作者：
Edd, Jon F.;Humphry, Katherine J.;Toner, Mehmet
形核和非平衡凝固的精确测量对于大气科学、食品加工、低温保存和冶金等领域至关重要。乳液技术，其中研究中的相被分配成许多液滴悬浮在不混溶的连续相中，是一种强大的方法，用于揭示成核速率和相变动力学，因为它将成核事件隔离到单个液滴。然而，对大量乳液中许多液滴的行为进行平均会导致任何液滴特定信息的丢失，并且液滴多分散性会使分析变得模糊。在这里，我们采用微流控技术捕获单分散液滴在平面阵列的特点凝固的高度过冷水溶液的甘油。该系统测得的成核速率在10（-5）pL（-1）s（-1）和10（-2）pL（-1）s（-1）之间，在-38 ℃和-35 ℃之间产生33.4 mJ m（-2）的冰水界面能，并且能够平行地观察到超过100滴的凝固的特定动力学，而没有任何特异性损失。除了所获得的物理见解，观察成核的时间和温度以及均匀液滴的静态阵列中固相的后续生长的能力提供了一个强大的工具来发现生成所需晶体结构的热力学协议。
The precise measurement of nucleation and non-equilibrium solidification are vital to fields as diverse as atmospheric science, food processing, cryopreservation and metallurgy. The emulsion technique, where the phase under study is partitioned into many droplets suspended within an immiscible continuous phase, is a powerful method for uncovering rates of nucleation and dynamics of phase changes as it isolates nucleation events to single droplets. However, averaging the behavior of many drops in a bulk emulsion leads to the loss of any drop-specific information, and drop polydispersity clouds the analysis. Here we adapt a microfluidic technique for trapping monodisperse drops in planar arrays to characterize solidification of highly supercooled aqueous solutions of glycerol. This system measured rates of nucleation between 10(-5) and 10(-2) pL(-1) s(-1), yielded an ice-water interfacial energy of 33.4 mJ m(-2) between -38 and -35 degrees C, and enabled the specific dynamics of solidification to be observed for over a hundred drops in parallel without any loss of specificity. In addition to the physical insights gained, the ability to observe the time and temperature of nucleation and subsequent growth of the solid phase in static arrays of uniform drops provides a powerful tool to discover thermodynamic protocols that generate desirable crystal structures.