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Title: Optically transparent and environmentally durable superhydrophobic coating based on functionalized SiO2 nanoparticles

Optical surfaces such as mirrors and windows that are exposed to outdoor environmental conditions are susceptible to dust buildup and water condensation. The application of transparent superhydrophobic coatings on optical surfaces can improve outdoor performance via a self-cleaning effect similar to the Lotus effect. The contact angle (CA) of water droplets on a typical hydrophobic flat surface varies from 100° to 120°. Adding roughness or microtexture to a hydrophobic surface leads to an enhancement of hydrophobicity and the CA can be increased to a value in the range of 16≥0° to 175°. This result is remarkable because such behavior cannot be explained using surface chemistry alone. When surface features are on the order of 100 nm or smaller, surfaces exhibit superhydrophobic behavior and maintain their optical transparency. In this work we discuss our results on transparent superhydrophobic coatings that can be applied across large surface areas. We have used functionalized silica nanoparticles to coat various optical elements and have measured the contact angle and optical transmission between 190 to 1100 nm on these elements. The functionalized silica nanoparticles were dissolved in a solution of the solvents isopropyl alcohol and 4-chlorobenzotrifluoride (PCBTF) and a proprietary ceramic binder (Cerakote ). Finally, thismore » solution was spin-coated onto a variety of test glass substrates, and following a curing period of about 30 minutes, these coatings exhibited superhydrophobic behavior with a static CA ≥160°.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Energy and Transportation Science Division
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Electrical and Electronics Systems Research Division
Publication Date:
OSTI Identifier:
1185439
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Nanotechnology
Additional Journal Information:
Journal Volume: 26; Journal Issue: 5; Journal ID: ISSN 0957-4484
Publisher:
IOP Publishing
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY superhydrophobic; anti-soiling; self-cleaing; transparent; nanoparticles