近日，智利大学的Ignacio Bordeu课题组通过研究发现了受限手性向列相液晶中的无序分支图案。相关成果已于2023年4月7日在国际学术期刊《美国科学院院刊》上发表。
该研究通过实验研究手性向列液晶细胞中热驱动分支模式的时空组织。研究人员发现，手性性质生成了指状体，调节了它们的相互作用并控制了尖端分裂过程。此外，研究人员展示了胆甾图案的复杂动态行为，如何通过分支和抑制手性指状体的概率过程来推动大尺度的拓扑组织。该研究的理论发现与实验观察结果相吻合。
据了解，空间分支过程在自然界中十分普遍，但不同系统中推动分支生长的机制可能存在显著差异。在软物质物理学领域，手性向列液晶为研究无序分支模式的出现和生长动力学提供了一个可控的环境。透过适当的强制作用，手性向列液晶中可以形成胆甾相，自组织成一个扩展的分支模式。已知，当胆甾指状体的圆头肿胀、不稳定并分裂成两个新的胆甾指状体时，分支事件就会发生。然而，界面不稳定性的起源以及推动这些胆甾模式的大尺度空间组织的机制仍不为人所知。
附：英文原文
Title: Emergence of disordered branching patterns in confined chiral nematic liquid crystals
Author: Echeverría-Alar, Sebastián, Clerc, Marcel G., Bordeu, Ignacio
Issue&Volume: 2023-4-7
Abstract: Spatial branching processes are ubiquitous in nature, yet the mechanisms that drive their growth may vary significantly from one system to another. In soft matter physics, chiral nematic liquid crystals provide a controlled setting to study the emergence and growth dynamic of disordered branching patterns. Via an appropriate forcing, a cholesteric phase may nucleate in a chiral nematic liquid crystal, which self-organizes into an extended branching pattern. It is known that branching events take place when the rounded tips of cholesteric fingers swell, become unstable, and split into two new cholesteric tips. The origin of this interfacial instability and the mechanisms that drive the large-scale spatial organization of these cholesteric patterns remain unclear. In this work, we investigate experimentally the spatial and temporal organization of thermally driven branching patterns in chiral nematic liquid crystal cells. We describe the observations through a mean-field model and find that chirality is responsible for the creation of fingers, regulates their interactions, and controls the tip-splitting process. Furthermore, we show that the complex dynamics of the cholesteric pattern behaves as a probabilistic process of branching and inhibition of chiral tips that drives the large-scale topological organization. Our theoretical findings are in good agreement with the experimental observations.
DOI: 10.1073/pnas.2221000120
Source: https://www.pnas.org/doi/10.1073/pnas.2221000120
来源：科学网 小柯机器人