Multi-layered Nanocoating of Nano and Submicron Sized Particles at Large Scale

原子层沉积(ALD)技术将被用于大规模修饰超细粒子的表面化学，并研究其在UVA/UVB透过率和自组装方面的应用。在研究的一个方面，将使用流态化过程在单个初级亚微米和纳米级无机颗粒的表面放置多层和纳米层状陶瓷薄膜。研究工作包括了解受粒间力影响并作为动态聚集体流态化的亚微米和纳米粒子的流态化行为，以及随后作为轻聚集体流态化的单个初级粒子的纳米涂层的能力。这是首次尝试通过ALD将纳米多层膜放置在流态化颗粒上。我们选择了一种防晒UVA/UVB体系(氧化锌/二氧化钛)，以提供具有良好特性的应用，以及测试复合粉末在非水配方(防晒液)中的行为的明确方法。在研究的另一个方面，通过ALD将无机纳米薄膜放置在纳米球粒子的表面，以控制其表面电荷(阴离子和阳离子)。含有相同浓度的相反电荷的纳米球的溶液将被研究离子自组装成纳米球的“盐”。研究将扩展到纳米衬底颗粒上的双层涂层，其中内层赋予纳米颗粒光学功能，外层赋予离子自组装电荷功能。以这种方式，将研究具有受控衍射图案的光子晶体阵列的自组装。该项目的总体目标是展示ALD在超细颗粒上的多层膜以及这种表面修饰颗粒在制剂和纳米颗粒阵列中的用途。这项新的研究为纳米颗粒表面化学的大规模控制提供了便利，促进了功能化纳米颗粒在配方中的使用和新型元件的制造。所要研究的纳米颗粒表面包覆方法是可行的，并且广泛适用于许多系统。这项研究为两名博士生和大约20名本科生提供了为期三年的独特教育体验。当地的工业合作伙伴ALD Nanosolution已同意与学生合作(例如，通过顶石设计项目)，以更好地了解研究的科学和应用方面，并促进技术转让。

Atomic Layer Deposition (ALD) processing will be carried out to modify the surface chemistry of ultrafine particles at large scale and to investigate the utility of the modified particles for UVA/UVB transmittance and self assembly. In one aspect of the research, multilayered and nanolaminated ceramic films will be placed on the surface of individual primary submicron and nanosized inorganic particles using a fluidized bed process. The research effort includes an understanding of the fluidization behavior of the submicron and nanosized particles that are affected by interparticle forces and that fluidize as dynamic aggregates, and the subsequent ability to nanocoat individual primary particles fluidizing as light aggregates. This is a first attempt to place nanothick multilayers on fluidized particles by ALD. A sunscreen UVA/UVB system (ZnO/TiO2) has been selected to provide for a well characterized application with definitive methods for testing the composite powder behavior in non-aqueous formulations (sunscreen lotions). In another aspect of the research, inorganic nanofilms will be placed on the surface of nanospherical particles by ALD to control their surface charge (anionic and cationic). Solutions containing equal concentration of oppositely charged nanospheres will be investigated for ionic self-assembly into nanospherical "salts". The investigation will be extended to bilayered coatings on nanosized substrate particles where the inner layer imparts optical functionality on the nanoparticles and the outer layer imparts charge functionality for ionic self assembly. In this manner, the self assembly of photonic crystalline arrays with controlled diffraction patterns will be investigated. The overall goal of the project is to demonstrate multi-layered films on ultrafine particles by ALD and the utility of such surface modified particles in formulations and nanofabricated arrays.This novel research provides for the large scale control of nanoparticle surface chemistry to facilitate the use of functionalized nanoparticles in formulations and for fabricating novel components. The nanoparticle surface coating method to be investigated is enabling and widely applicable to many systems. This research provides for a unique educational experience for two Ph.D. students and approximately 20 undergraduates over the three year program. A local industrial partner, ALD Nanosolutions, has agreed to work with the students (e.g., through capstone design projects) to better understand both the scientific and applied aspects of the research and to facilitate technology transfer.