NER: 3D Nanocolloidal Crystallization via Electrokinetic Flows

我们最近开发了一种新的和通用的方法，使胶体粒子到三维晶体快速和可逆地使用电场。有序机制似乎依赖于诱导偶极相互作用和流体动力学流动的组合，将粒子推到一起，产生有效的吸引力。由于这些相互作用可以通过施加的场特性和限制几何形状的组合来缓和，因此它们的大小可以大大调整并用于使各种尺寸范围内的颗粒结晶。我们的初步调查集中在胶体的大小范围从250 nm到50 nm的半径，所有这些都可以通过施加外部场可逆地结晶。我们还表明，这些胶体晶体的成核可以通过选择性地施加电场来空间控制。这里提出的工作的目标是将这些初步调查扩展到整个纳米尺度范围内的更小的长度尺度。我们打算利用这一点的可逆性和空间寻址的纳米粒子的结晶。除了创建一个显示技术与廉价的材料，我们设想的可切换的光子带隙材料的基础上的纳米胶体大小的材料的可逆排序的发展。 该奖项由化学和运输系统部门的热运输和热处理计划以及颗粒和多相过程计划资助。

We have recently developed a novel and general means of ordering colloidal particles into three-dimensional crystals rapidly and reversibly using electric fields. The ordering mechanism appears to rely on a combination of induced dipole interactions and hydrodynamic flows that push particles together, creating an effective attraction. Because these interactions can be moderated with a combination of applied field properties and confining geometry, their magnitude can be greatly tuned and used to crystallize particles in a wide variety of size ranges. Our preliminary investigations have focused on colloids ranging in size from 250 nm down to 50 nm in radius, all of which can be reversibly crystallized through application of the external field. We have also shown that nucleation of these colloidal crystals can be spatially controlled solely through selective application of the electric field. The goal of the work proposed here is to extend these preliminary investigations into smaller length scales throughout the nanoscale range. We intend to take advantage of this for the reversible and spatially addressable crystallization of nanoscale particles. In addition to the creation of a display technology with inexpensive materials, we envision the development of switchable photonic band gap materials based upon the reversible ordering of nanocolloidal-sized materials. The award has been funded by the Thermal Transport and Thermal Processing Program and the Particulate and Multiphase Processes Program of the Chemical and Transport Systems Division.