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Colloidal aggregation in anisotropic liquid crystal solvent
Soft Matter ( IF 2.9 ) Pub Date : 2021-07-23 , DOI: 10.1039/d1sm00542a
Devika Gireesan Sudha 1 , Jocelyn Ochoa , Linda S Hirst
Affiliation  

The mutual attraction between colloidal particles in an anisotropic fluid, such as the nematic liquid crystal phase, leads to the formation of hierarchical aggregate morphologies distinct from those that tend to form in isotropic fluids. Previously it was difficult to study this aggregation process for a large number of colloids due to the difficulty of achieving a well dispersed initial colloid distribution under good imaging conditions. In this paper, we report the use of a recently developed self-assembling colloidal system to investigate this process. Hollow, micron-scale colloids are formed in situ in the nematic phase and subsequently aggregate to produce fractal structures and colloidal gels, the structures of which are determined by colloid concentration and temperature quench depth through the isotropic to nematic phase transition point. This self-assembling colloidal system provides a unique method to study particle aggregation in liquid crystal over large length scales. We use fluorescence microscopy over a range of length scales to measure aggregate structure as a function of temperature quench depth, observe ageing mechanisms and explore the driving mechanisms in this unique system. Our analyses suggest that aggregate dynamics depend on a combination of Frank elasticity relaxation, spontaneous defect line annihilation and internal aggregate fracturing.

中文翻译:

各向异性液晶溶剂中的胶体聚集

各向异性流体(如向列型液晶相)中胶体颗粒之间的相互吸引导致分层聚集形态的形成,这与在各向同性流体中倾向于形成的形态不同。以前,由于难以在良好的成像条件下实现良好分散的初始胶体分布,因此很难研究大量胶体的这种聚集过程。在本文中,我们报告了使用最近开发的自组装胶体系统来研究这一过程。原位形成中空的微米级胶体在向列相中,随后聚集以产生分形结构和胶体凝胶,其结构由胶体浓度和温度淬火深度通过各向同性到向列相转变点决定。这种自组装胶体系统提供了一种独特的方法来研究大尺度液晶中的粒子聚集。我们在一系列长度尺度上使用荧光显微镜来测量聚集体结构作为温度淬灭深度的函数,观察老化机制并探索这个独特系统中的驱动机制。我们的分析表明,骨料动力学取决于弗兰克弹性松弛、自发缺陷线湮灭和内部骨料破裂的组合。
更新日期:2021-07-29
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