Guzmán O, Abbott N L, de Pablo J J
Department of Chemical and Biological Engineering, University of Wisconsin, Madison, Wisconsin 53706-1691, USA.
J Chem Phys. 2005 May 8;122(18):184711. doi: 10.1063/1.1896354.
We analyze the response of a nematic liquid-crystal film, confined between parallel walls, to the presence of nanoscopic particles adsorbed at the walls. This is done for a variety of patterns of adsorption (random and periodic) and operational conditions of the system that can be controlled in experimental liquid-crystal-based devices. We compute simulated optical textures and the total optical output of the sensor between crossed polars, as well as the correlation function for the liquid-crystal tensor order parameter; we use these observables to discuss the gradual destruction of the original uniform orientation. For large concentrations of particles adsorbed in random patterns, the liquid crystal at the center of the sensor adopts a multidomain state, characterized by a small correlation length of the tensor order parameter, and also by a loss of optical anisotropy under observation through crossed polars. In contrast, for particles adsorbed in periodic patterns, the nematic at the center of the cell can remain in a monodomain orientation state, provided the patterns in opposite walls are synchronized.
我们分析了夹在平行壁之间的向列型液晶薄膜，对吸附在壁上的纳米颗粒的响应。这是针对多种吸附模式（随机和周期性）以及系统的操作条件进行的，这些条件在基于液晶的实验装置中是可以控制的。我们计算了模拟的光学纹理以及传感器在正交偏振器之间的总光学输出，还有液晶张量序参量的相关函数；我们用这些可观测量来讨论原始均匀取向的逐渐破坏。对于以随机模式吸附的大量颗粒，传感器中心的液晶呈现多畴状态，其特征是张量序参量的相关长度较小，并且在通过正交偏振器观察时光学各向异性也会丧失。相比之下，对于以周期性模式吸附的颗粒，只要相对壁上的模式同步，盒中心的向列相就可以保持在单畴取向状态。
