Soft Materials Research Center and Department of Physics, University of Colorado Boulder, Boulder, CO 80309, USA.
Soft Matter. 2017 Sep 27;13(37):6314-6321. doi: 10.1039/c7sm01584d.
We report a novel type of two-dimensional colloidal emulsion, in which arrays of disc-shaped liquid crystal domains are created in ultrathin, freely-suspended, fluid smectic C liquid crystal films. After a film has been drawn across an aperture, an island emulsion is produced by repeatedly compressing and expanding the film while maintaining vigorous shear and extensional air flow across its area. Once formed, these emulsions restructure over a period of a few minutes to a stable state that then changes only slowly, over the course of several days. This stability enables study of the sedimentation of the emulsion under in-plane gravitation produced by tilting the film, during which the original island emulsion segregates into regions with different kinds of emulsions distinguished by the size, density, and degree of order of the islands. We observe a rich array of phenomena that includes the formation of chains of islands organized into two-dimensional smectics in the dilute phase, and island deformation and coalescence in the condensed phase.
我们报告了一种新型二维胶体乳状液，其中在超薄的自由悬浮的流态近晶 C 型液晶膜中形成了圆盘状液晶畴的阵列。在薄膜穿过一个孔之后，通过在保持强烈剪切和横跨其面积的拉伸空气流的同时反复压缩和扩展该薄膜，产生岛状乳状液。一旦形成，这些乳状液在几分钟到几天的时间内经历重构，达到稳定状态，然后在数天的过程中缓慢变化。这种稳定性使得可以在通过倾斜薄膜产生的面内重力下研究乳状液的沉降，在这个过程中，原始的岛状乳状液分离成具有不同类型乳状液的区域，这些区域通过岛的大小、密度和有序度来区分。我们观察到了一系列丰富的现象，包括在稀释相中组织成二维近晶的岛的链的形成，以及在凝聚相中岛的变形和聚结。
