Dolganov P V, Zverev A S, Baklanova K D, Dolganov V K
Institute of Solid State Physics RAS, 142432, Chernogolovka, Moscow Region, Russia.
National Research University Higher School of Economics, Moscow, 101000, Russia.
Soft Matter. 2021 Dec 22;18(1):126-136. doi: 10.1039/d1sm01334c.
We investigated the coalescence of nematic droplets in an isotropic environment and that of isotropic droplets in a nematic environment in quasi-two-dimensional geometry of a flat optical cell. Two different regimes of coalescence were found. In the circular meniscus between the nematic and isotropic regions both nematic and isotropic phases exist. As a result, two bridges form at coalescence: a nematic and an isotropic bridge. In this work, we focus on the situation when nematic wets the cell surface. The coalescence of nematic droplets starts near the cell surfaces where the droplet bridge from the nematic phase is formed. An outer bridge connecting the isotropic environment is localized in the middle of the cell. When the outer bridge gets thinner it becomes unstable and breaks up. A series of pinch-offs leads to the formation of satellite droplets. On the contrary, when isotropic droplets coalesce, the coalescence starts in the middle of the cell and breaking of the bridges occurs without instability and without the formation of satellite droplets. Breakup of the outer bridge is a new example of Rayleigh-Plateau instability in addition to actively studied transformation and breaking of filaments and stretched droplets.
我们在平面光学池的准二维几何结构中，研究了向列相液滴在各向同性环境中的聚并以及各向同性液滴在向列相环境中的聚并。发现了两种不同的聚并模式。在向列相和各向同性区域之间的圆形弯月面中，向列相和各向同性相均存在。因此，聚并时会形成两个桥：一个向列相桥和一个各向同性桥。在这项工作中，我们关注向列相润湿池表面的情况。向列相液滴的聚并始于池表面附近，在此处形成来自向列相的液滴桥。连接各向同性环境的外桥位于池的中部。当外桥变细时，它会变得不稳定并破裂。一系列缩颈导致卫星液滴的形成。相反，当各向同性液滴聚并时，聚并始于池的中部，桥的破裂不会产生不稳定性，也不会形成卫星液滴。除了对细丝和拉伸液滴的转化与破裂进行了积极研究外，外桥的破裂是瑞利 - 普拉托不稳定性的一个新例子。
