Low Temperature Transparent Nanoplatelet Hybrid Gas Barrier Coating Materials via Sol-gel Process
- PDF / 453,356 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 83 Downloads / 151 Views
1114-G05-04
Low Temperature Transparent Nanoplatelet Hybrid Gas Barrier Coating Materials via Sol-Gel Process Masahiro Asuka 1,2and Wolfgang M. Sigmund1 1 Department of Materials Sciences and Engineering, University of Florida, 225 Rhines Hall, Gainesville, FL 32611, U.S.A. 2 Sekisui Chemical Co., Ltd., 2-1 Hyakuyama Shimamoto-Cho Mishima-Gun, Osaka, 618-8589, Japan. ABSTRACT A novel hybrid coating based on a combination of nanoparticles, sol-gel and organic chemistry is reported. It can be applied to a large variety of surfaces even at low processing temperatures, and it cures below 150°C. Furthermore, fabrication of the hybrid films on polymer sheets can be done under ambient conditions. No vacuum techniques are required. Boehmite nanoplatelet composite hybrid organic/inorganic coating materials have been successfully prepared via this approach. The coating process involves the dispersion of boehmite nanoparticles that are suspended without significant agglomeration. 3-glycidoxy propyl trimethoxy silane (GPTMS) was adopted as dispersant for the nanoplatelets and functions also as a network former. This induces flexibility in the hybrid film due to the organic functional groups. Transparent cured coatings from flexible to brittle were obtained from a single coating step with thicknesses in excess of 10 µm depending on the ratio of the inorganic/organic reagents and their concentrations. Barrier coatings with more than 60wt% ceramic nanoplatelets were achieved, yet they still display transparency of more than 95% to visible light with no cracks or other discernable defects. Several substrates have been successfully tested including poly (ethylene terephthalate) (PET). Moreover water permeability for cured coated PET films is reduced to less than 0.01 g/m2/d. Excellent mechanical properties such as flexibility and hardness are demonstrated by nanoindentation and scratch tests. INTRODUCTION Plastics have been used for transparent articles and are superior to glass equivalents with regard to many material properties, in that they are light weight, foldable, conformal and low cost. However, there are a number of shortcomings in their physical properties that limit many of their applications. First, there is the low hardness of the plastic that makes it prone to scratching. Second, plastics can be a rather poor diffusion barrier to water, chemicals and gases, especially oxygen. Therefore, gas barrier coatings on flexible substrates have received much attention in industry. For many technologies under development, such as organic solar cells, liquid crystal displays (LCDs), and organic light emitting diodes (LEDs), encapsulants and coatings with very low permeability of water and oxygen are required. Silicone hard coatings are a type of hard coating prepared by a sol-gel process. A typical coating procedure used to make silicone hard coated polycarbonate or other polymeric article is published by Sanchez and others. [1,2,3] Such coatings typically require a primer coating between the plastic and the hard coating and are
Data Loading...
