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Persistent superhydrophilicity of sol-gel derived nanoporous silica thin films

Ganjoo, S ; Sharif University of Technology | 2009

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  1. Type of Document: Article
  2. DOI: 10.1088/0022-3727/42/2/025302
  3. Publisher: 2009
  4. Abstract:
  5. In this investigation, sol-gel synthesized nanoporous silica thin films, annealed at different temperatures, with long time superhydrophilic property have been studied. Two kinds of sol-gel silica thin films were fabricated by dip-coating of glass substrates in two different solutions; with low and high water. The transparent coated films were dried at 100 °C and then annealed in a temperature range of 200-500 °C. The average water contact angle of the silica films prepared with low water content and annealed at 300 °C measured about 5° for a long time (6 months) without any UV irradiation. Instead, adding water into the sol resulted in silica films with an average water contact angle greater than 60°. Atomic force microscopic analysis revealed that the silica films prepared with low water had a rough surface (∼30 nm), while the films prepared with high water had a smoother surface (∼2 nm). Using x-ray photoelectron spectroscopy, we have shown that with a decrease in the surface water on the film, its hydrophilicity increases logarithmically. © 2009 IOP Publishing Ltd
  6. Keywords:
  7. Annealing ; Contact angle ; Gelation ; Gels ; Silica ; Sol-gel process ; Sol-gels ; Sols ; Thin films ; Water analysis ; Water content ; X ray photoelectron spectroscopy ; Atomic forces ; Coated films ; Dip coatings ; Glass substrates ; High waters ; Low water contents ; Low waters ; Microscopic analysis ; Nanoporous silicas ; Rough surfaces ; Silica films ; Sol-gel silicas ; Super hydrophilicities ; Super-hydrophilic properties ; Temperature ranges ; Uv irradiations ; Water contact angles ; X-ray photoelectron spectroscopies ; Film preparation
  8. Source: Journal of Physics D: Applied Physics ; Volume 42, Issue 2 , 2009 ; 00223727 (ISSN)
  9. URL: https://iopscience.iop.org/article/10.1088/0022-3727/42/2/025302