Deposition of Polymer Thin Films on ZnO Nanoparticles by a Plasma Treatment
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Deposition of Polymer Thin Films on ZnO Nanoparticles by a Plasma Treatment Peng He, Jie Lian1, L. M. Wang1, Wim J. van Ooij, and Donglu Shi, Department of Materials Science and Engineering, University of Cincinnati Cincinnati, OH 45221-0012 1 Dept. of Nuclear Engineering and Radiological Science, University of Michigan Ann Arbor, MI 48109 ABSTRACT Ultrathin acrylic acid polymer films have been deposited on the surfaces of nanoparticles of ZnO using a plasma polymerization treatment. The average size of nanoparticles is on the order of 50 nm in irregular shapes. High-resolution transmission electron microscopy (HRTEM) experiments showed that an extremely thin film of the acrylic acid layer (15 nm) was uniformly deposited on the surfaces of the nanoparticles. In particular, the particles of all sizes exhibited equally uniform ultrathin films indicating a well-dispersed nanoparticles in the fluidized bed during the plasma treatment. The deposition mechanisms and the effects of plasma treatment parameters are discussed. INTRODUCTION Nanoparticles are known to have extremely high surface areas. As a result of the high surface area, the surface energy can reach the order of 100 kJ/mol for a variety of materials (1-5). Due to high surface areas, nanoparicles naturally agglomerate and can form considerable bonding between particles. If they strongly bond to each other, they cannot be easily dispersed and are referred to as an aggregate or a hard agglomerate. Therefore, for nanoscale particles, the challenge is that whether they can be well dispersed in space. Furthermore, in a well-dispersed condition, whether it is possible to coat uniformly a thin layer of foreign species on their particle surfaces. In this proposal we will address these issues and focus on the optimization of experimental procedures. Surface coating of nanoparticles is an important area in nanomaterials synthesis. Because of their special composition, these coatings possess a unique combination of properties of the inorganic and organic components, for instance hydrophobic, hydrophilic, anti-fogging, anti-fouling, anti-adhesive and/or teflon-like properties in combination with hardness and scratch and abrasive resistance. The combination of mutually chemically interconnected organic and inorganic networks results in coatings with a very low permeability for gases and liquids. Hybrid materials are very suitable for application as coatings on a highly diverse spectrum of substrates including glasses, ceramics, plastic, wood, and metal. Before curing, the coating materials consists of a clear alcoholic solution that can easily be processed by classical application techniques such as dipping, spraying, or spin coating. However, in these previous coating processes, the coatings are quite thick up to the order of microns. The current trend of developing nanophase materials has motivated an increased need for nanometer-scale structures in a variety of applications. Indeed, it is clear that, in order to achieve unique mechanical, physical, chemical, and biomedi
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