Molecular simulations of entangled defect structures around nanoparticles in nematic liquid crystals

We investigate the defect structures forming around two nanoparticles in a Gay–Berne nematic liquid crystal using molecular simulations. For small separations, disclinations entangle both particles forming the figure of eight, the figure of omega and the figure of theta. These defect structures are similar in shape and occur with a comparable frequency to micron-sized particles studied in experiments. The simulations reveal fast transitions from one defect structure to another suggesting that particles of nanometre size cannot be bound together effectively. We identify the ‘three-ring’ structure observed in previous molecular simulations as a superposition of the different entangled and non-entangled states over time and conclude that it is not itself a stable defect structure.

本研究借助分子模拟方法，探究了盖-贝雷（Gay–Berne）向列相液晶中两个纳米颗粒周围形成的缺陷结构。当两颗粒间距较小时，向错会缠绕两个颗粒，形成八字形、Ω形以及θ形三种缺陷结构。上述缺陷结构的形态与实验中研究的微米级颗粒所形成的缺陷结构相似，且出现频率相当。模拟结果显示，不同缺陷结构间存在快速转变，这表明纳米级颗粒无法实现有效的相互结合。本研究将既往分子模拟中观测到的‘三环’结构，归因于不同缠绕与非缠绕状态随时间的叠加，并得出结论：该结构本身并非稳定的缺陷结构。