Page 129 - Handbook of Surface Improvement and Modification

124 Easy Surface Cleaning and Stain Inhibition

Figure 8.3. Self-cleaning glass: (1) dirt accumulation, (2) UV degradation of the organic dirt, and (3) rain water
removal. [Courtesy of Pilkington]
rier layer was created by boron diffusion
into the top 10-50 nm thick layer of glass
7
surface. The alkali mobility was electro-
chemically arrested by a coordination
7
change of boron. When three-coordinated
boron diffuses into a pre-existing glass net-
work, it converts nonbridging oxygens,
associated with alkali ions, into bridging
oxygens by changing its coordination from
7
3 to 4. This forces alkali ions to change
their bond association from nonbridging
oxygens to the charge sphere of boron due
to the required charge neutrality which
7
immobilizes the alkali ions.
Titanium dioxide generates electrons
and holes on irradiation. Most organic
micro-pollutants, including dioxins, are
decomposed into carbon dioxide and water
under the effect of the holes having high
8
oxidative potential. A photocatalyst having
high-activity have been developed for
transparent coatings utilized on a broad
Figure 8.4. AFM 3D topography images of the coatings 8
deposited on glass: (A) silane OH100, (B) silane BS290, range of materials. The high-activity pho-
(C) 14% PDMS, (D) 28% PDMS, (E) 42% PDMS, and tocatalyst has been studied in deodoriza-
(F) 56% PDMS. [Adapted, by permission, from tion, anti-bacterial, self-cleaning, anti-stain,
Illescas, JF; Mosquera, MJ, J. Phys. Chem., 115,
14624-34, 2011.]