NER: Ordered liquid crystal nano-colloids

纳米粒子可以在液晶中形成复杂的三维结构。我们的初步研究表明，向各向同性相界移动的液晶收集和推动并周期性地沉积纳米颗粒。通过调整各种条件，如相变的速度、液晶类型的排列、颗粒的大小和形状，我们可以产生各种各样的三维结构。我们还发现，外场的应用，特别是图案化的外场可以与相变相结合来产生非常复杂的结构。这项提案概述了一个积极的研究项目，旨在探索这些新发现的现象的基本机制，这些现象可能产生复杂的三维结构。该项目与纳米尺度的纳米结构、新现象和制造工艺密切相关，同时与纳米尺度器件和系统架构主题相关。我们建议利用液晶研究所(俄亥俄州肯特州立大学)的独特研究优势来快速产生新的电光材料，并为理解这一复杂过程奠定理论基础。我们将专注于精确控制分散在液晶基质中的纳米粒子的位置。分散在液晶相中的颗粒会在液晶指向矢中产生扭曲，并在液晶相中引入缺陷。在这些扭曲和缺陷中发现的额外能量提供了推动纳米颗粒运动的力量。为了使系统的自由能最小，粒子将共享缺陷并倾向于形成有序的结构。这些结构往往位于分隔液晶区域的缺陷线和缺陷面上，这为形成复杂的三维结构提供了最简单的机制。锚定在粒子表面可以在其附近诱导向列序参数的大小梯度，导致粒子之间有吸引人的短程相互作用。更复杂的相互作用源于粒子表面附近的指向矢场中热涨落的限制。通过调制这些复杂的能量系统，我们有可能精确地控制纳米粒子的放置。作为这种新方法的威力的一个例子，我们将构建复杂的三维光子晶体，将不同尺寸和物理性质的粒子排列成有序的阵列。例如，我们可以分离不同类型的颗粒：铁电、铁磁和碳纳米管。这些悬浮液的弹性、电学、磁学和非线性光学特性将作为颗粒的物理性质、浓度、大小和形状的函数进行实验和理论研究。这些复杂的阵列可以用来制造新的光学设备、人造肌肉、响应膜和生物传感器。智能价值我们的研究结果将是一套新的工具，研究人员可以用来构建纳米粒子结构并创造全新的影响。我们还将扩展我们对液晶相的一般理解。例如，我们已经发现，纳米颗粒在各向同性界面上的运动为了解这一复杂边界的属性提供了新的视角。广泛影响我们将利用我们现有的产业伙伴计划来确保我们的成果迅速传输到市场。通过LCI暑期实习计划和KSU REU计划，我们将接触到本科生，并通过我们既定的教育推广计划，我们将与该地区的K-12学生进行互动。

Complex three dimensional structures of nanoparticles can be produced in liquid crystals. Our preliminary research demonstrates that a moving liquid crystal to isotropic phase boundary collects and pushes and periodically deposits nanoparticles. By adjusting a variety of conditions, such as the rate of the phase transition, the alignment of type of liquid crystal, the size and shape of particles, we can produce a wide variety of three dimensional structures. We have also found that application of external fields and in particular patterned external fields can be combined with the phase transition to produce very complex structures. This proposal outlines an aggressive research project to explore the basic mechanisms of these newly discovered phenomena potential to produce complex three dimensional structures. This project is most closely related to the Nanoscale Structures, Novel Phenomena and Manufacturing Processes at the Nanoscale, while having relevance for the Nanoscale Devices and System Architecture theme.We propose to deploy the unique research strengths at the Liquid Crystal Institute (Kent State University, Ohio) to rapidly result in new electro-optical materials and establish a theoretical base to understand this complex process We will focus on precisely controlling the position of nano-particles dispersed in liquid crystalline matrices. Particles dispersed in the liquid crystal phase produce distortions in the liquid crystal director and introduce defects in the liquid crystal phase. The added energy found in these distortions and defects provide the forces that move the nanoparticles. In order to minimize the free energy of the system, particles will share defects and tend to form organized structures. These structures will tend to reside at defect lines and planes separating liquid crystal domain providing the simplest mechanism to produce complex three dimensional structures.Anchoring at the particle surface can induce a gradient in the magnitude of the nematic order parameter in their neighborhood, leading to an attractive short-range interaction between particles. More complex interactions arise from restrictions of thermal fluctuations in the director field near the particle surfaces. By modulating these complex systems of energies we have the potential to precisely control the placement of nano-particles.As an example of the power of this new approach we will build complex three dimensional photonic crystals that arrange particles of different sizes and physical properties in ordered arrays. For example we can segregate particles of different types: ferro-electric, ferro-magnetic, and carbon nanotubes. The elastic, electro-, magneto-, and nonlinear optical properties of these suspensions will be investigated experimentally and theoretically as a function of the physical properties, concentration, size, and shape of the particles. These complex arrays can be used to produce new optical devices, artificial muscles, responsive membranes and biological sensors.Intellectual meritThe result of our research will be a new set of tools researchers can use to build nano-particle structures and create entirely new affects. We will also expand our general understanding of the liquid crystal phase. For example, we have already found that the movement of nanoparticles at the isotropic interface provides new insight into the properties of this complex boundary.Broader impactWe will utilize our existing Industrial Partnership Program to assure that our results are quickly transmitted to the marketplace. Through the LCI summer internship program and the KSU REU program we will reach out to undergraduate students and through our established education outreach program we will interact with K-12 students in the area.