Ordered patterns of liquid crystal toroidal defects by microchannel confinement
Ordered patterns of liquid crystal toroidal defects by microchannel confinement
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DOI：
10.1073/pnas.0407925101
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发表时间：
2004-12-14
影响因子：
11.1
通讯作者：
Safinya, CR
中科院分区：
文献类型：
--
作者：
Choi, MC;Pfohl, T;Safinya, CR
在这篇文章中，我们提出的实验结果表明，在近晶液晶（LC）的表面改性微通道的几何限制的大小和空间图案的缺陷域控制的方法。通过将LC 4 '-辛基-4-氰基联苯限制在具有受控表面极性的微米尺寸的矩形通道中，我们能够产生不仅尺寸几乎均匀而且以准二维有序图案排列的缺陷域。原子力显微镜的测量结果表明，缺陷有一个环形的拓扑结构，我们认为这是由微通道的壁所施加的边界条件。我们表明，缺陷可以被认为是胶体物体，它们相互作用，形成有序的图案。这种方法开辟了利用与LC缺陷相关的独特光学和流变学性质来制造新材料的可能性。例如，在中尺度上控制缺陷的形状、尺寸和空间排列表明了在图案化、模板化中的应用，并且当扩展到溶致LC时，这是一种导致用于化学封装和递送的均匀尺寸的球形颗粒的过程。
In this article we present experimental results demonstrating an approach to controlling the size and spatial patterning of defect domains in a smectic liquid crystal (LC) by geometric confinement in surface-modified microchannels. By confining the LC 4'-octyl-4-cyanobiphenyl in mum-sized rectangular channels with controlled surface polarity, we were able to generate defect domains that are not only nearly uniform in size but also arranged in quasi-2D ordered patterns. Atomic force microscopy measurements revealed that the defects have a toroidal topology, which we argue is dictated by the boundary conditions imposed by the walls of the microchannel. We show that the defects can be considered to be colloidal objects, which interact with each other to form ordered patterns. This method opens the possibility for exploiting the unique optical and theological properties associated with LC defects to making new materials. For example, the control of the shape, size, and spatial arrangement of the defects at the mesoscale suggests applications in patterning, templating, and when extended to lyotropic LCs, a process leading to uniform-sized spherical particles for chemical encapsulation and delivery.