Fundamental studies of liquid crystal nanodroplets

非技术概述液晶由细长的分子组成，这些分子可以组装成有序的结构，让人想起固体晶体中的原子所假设的结构，同时保持流体状态。这种有序的结构可以用来操纵光--这是液晶显示器中利用的一种特性。液晶的一个有趣的特性是它们的结构可以通过界面处的小扰动而改变;因此液晶可以作为放大器，能够在相对长的距离上传输分子事件。这种特性已被用于开发特定分子的传感器，包括毒素，其中在液体界面处的吸附引发一系列分子转化，导致宏观颜色变化，可以可靠且廉价地检测。在这个项目中，PI将使用理论和计算来推进对一系列事件的理解，从分子或纳米粒子被吸附在液晶-水或液晶-蒸汽界面的那一刻起，到随后导致可测量光学响应的结构变化。从这个项目中获得的知识将有助于液晶传感技术的发展，这些技术可能会增强或超过今天的技术，特别是在生物毒素领域，PI旨在将该项目的科学和计算方面部分融入高中生暑期讲习班和旨在向少数民族介绍计算的推广活动芝加哥市中心公立学校的学生。技术总结该奖项支持理论和计算研究和教育，以促进对液晶界面的基本理解。 PI旨在开发能够描述原子、介观和宏观长度尺度的预测分子模型。这里考虑的主要物理几何形状将由液晶液滴组成，其界面将与水或空气接触。 在原子水平上，分子模拟将用于预测材料特性，例如界面处的分子构象，这些特性难以通过实验测量并且通常无法获得。在稍长的长度尺度上，分子的粗粒度模型将用于预测和检查纳米颗粒负载LC系统中出现的缺陷，从而直接描述不同的形态如何响应异物和外部刺激。在更长的长度尺度上，连续模型将用于理解液滴及其界面的不同区域中表面活性分子或纳米级颗粒的排列或分离，以及这些系统内有序结构的形成。这种模型将依赖于材料属性和基于更精细、原子级和粗粒度描述水平生成的见解。从这个项目中出现的LC系统的研究的理论和计算形式主义将提供一些有吸引力的功能，包括描述感兴趣的非均匀材料及其结构和热力学性质的大型，全三维实现的能力。这种形式主义将用于识别由三维LC系统与二维装饰界面的耦合所控制的新物理现象，并将作为筛选有希望的材料组合和演示本提案中提出的概念的工具。PI旨在将该项目的科学和计算方面部分融入高中生夏季研讨会和外展活动旨在向芝加哥市中心公立学校的少数民族学生介绍计算。

NONTECHNICAL SUMMARYLiquid crystals consist of elongated molecules that can pack into ordered structures, reminiscent of those assumed by atoms in solid crystals, while remaining fluid. Such ordered structures can be used to manipulate light - a property that is exploited in liquid crystal displays. An interesting feature of liquid crystals is that their structure can be altered through small perturbations at an interface; the liquid crystal can therefore serve as an amplifier, capable of transmitting molecular events over relatively long distances. This property has been used to develop sensors for specific molecules, including toxins, in which adsorption at a liquid interface triggers a series of molecular transformations that result in macroscopic color changes, which can be detected reliably and inexpensively. In this project, the PI will use theory and computation to advance understanding of the series of events, from the moment a molecule or a nanoscopic particle is adsorbed at a liquid crystal-water or at a liquid crystal-vapor interface, to the ensuing structural changes that lead to measurable optical responses. The knowledge gained from this project will contribute to the development of liquid crystal sensing technologies that could augment or surpass those available today, particularly in the realm of biological toxins, thereby leading to important societal benefits.The PI aims to integrate science and computational aspects of this project in part into a summer workshop for high school students and an outreach activity aimed to introduce computation to minority students in inner city Chicago public schools.TECHNICAL SUMMARYThis award supports theoretical and computational research and education to advance the fundamental understanding of liquid crystal interfaces. The PI aims to develop predictive molecular models capable of describing atomistic, mesoscale, and macroscopic length scales. The primary physical geometry considered here will consist of liquid crystal droplets, whose interfaces will be in contact with water or air. At the atomistic level, molecular simulations will be used to predict material properties, such as molecular conformation at an interface, that are difficult to measure experimentally and are often unavailable. At slightly longer length scales, coarse-grained models of the molecules will be used to predict and examine the defects that arise in nanoparticle-laden LC systems, thereby providing a direct description of how different morphologies respond to foreign bodies and external stimuli. At even longer length scales, continuum models will be used to understand the arrangement or segregation of surface-active molecules or nanoscopic particles in distinct regions of the droplets and their interfaces, and the formation of ordered structures within such systems. Such models will rely on the material properties and insights generated on the basis of finer, atomistic and coarse-grained levels of description. The theoretical and computational formalism for study of LC systems that will emerge from this project will offer a number of attractive features, including the ability to describe large, fully three-dimensional realizations of the inhomogeneous materials of interest and their structural and thermodynamic properties. That formalism will serve to identify new physical phenomena governed by the coupling of a three-dimensional LC system to a two-dimensional, decorated interface, and will serve as a screening tool for promising materials combinations and for demonstration of the concepts put forth in this proposal.The PI aims to integrate science and computational aspects of this project in part into a summer workshop for high school students and an outreach activity aimed to introduce computation to minority students in inner city Chicago public schools.