Page 139 - Handbook of Surface Improvement and Modification

134 Easy Surface Cleaning and Stain Inhibition

8.3 APPLICATION DATA

Stimuli-responsive self-cleaning aqueous coating compositions for masonry which con-
tains coating exhibiting reversible superhydrophobic and superhydrophilic behavior in
response to the external stimuli such as variation in temperature, pH, humidity, and light. 33
The coating exhibits low contact angle hysteresis of <25 degrees which reversibly
33
switches to a contact angle hysteresis of >25 degrees with external stimuli. The aqueous
coating composition comprises a polymeric dispersion of either acrylic, fluorinated and
amine backbone or acrylic, fluorinated and acid backbone in combination with hydropho-
bic and hydrophilic silicones and partially surface treated particles (e.g., silica or titanium
33
dioxide) having a balance of hydrophobicity and hydrophilicity.
A transparent electrodynamic screen enables automatic removal of dust to protect
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and enhance performance of solar collectors and similar components. A pattern of trans-
parent conductive electrodes are deposited over a glass or polymer outer surface of a solar
collector and embedded under a thin, transparent dielectric fluoropolymer film or silicon
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dioxide coating. When energized by three-phase voltages at frequencies in the range of 5
to 20 Hz, the electrodes produce an oscillating electric field and a traveling electrody-
namic wave that charges the particles on the surface and exerts coulomb and dielectropho-
retic forces to lift the dust from the surface and transport it to an edge of the collector,
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thereby clearing the screen. The EDS can be incorporated in the collector in an inte-
34
grated way during manufacture or retrofitted to the existing conventional collectors.
The surfaces of nanosilica particles are modified with siloxane substituents contain-
ing aldehyde functional groups resulting in particles which can be readily incorporated
into compositions, such as polymeric coating compositions, to improve scratch resistance,
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dirt pick-up resistance, and anti-adhesion properties. Provided are the novel silica parti-
35
cles, a simple economic process for their preparation, and dirt repellent coatings.
36
A surface can be coated with a liquid repellent coating. Materials for making the
liquid repellent coating (e.g., a fingerprint resistant coating) can be selected on the basis of
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surface energy considerations, such as a receding surface energy. The materials can
include a polymer and a liquid repelling material, for example, polyethylmethacrylate and
36
a fluorinated silsesquioxane such as fluorodecyl POSS.
37
A composition that upon firing, forms a non-stick enamel layer is disclosed. The
composition can be applied to a metal substrate to provide a non-stick, durable coating for
37
cooking surfaces. Also disclosed are methods of forming enamel layers and correspond-
37
37
ing coated substrates. Various ground coats and related methods are described. Various
multilayer coatings and structures are disclosed that include an enamel layer and a ground
37
coat layer.
REFERENCES
1 Birch, W; Carre, A; Mittal, KL, Wettability Techniques to Monitor the Cleanliness of Surfaces in
Developments in Surface Contamination and Cleaning, Kohli, R; Mittal, KL, Eds., WilliamAndrew Inc.,
2008, pp. 693-723.
2 Blel, W; Dif, M; Sire, O, J. Environ. Management, 155, 1-10, 2015.
3 Guo, J; Resnick, P; Efimenko, K; Genzer, J; DeSimone, JM, Ind. Eng. Res., 47, 502-8, 2008.
4 Markets for Self-Cleaning Coatings and Surfaces: 2015 to 2022. NanoMarkets 2015.
5 Roy, S; Suresh, VM; Maji, TK, Chem. Sci., 7, 2251-6, 2016.
6 Varsheney, P; Lomga, J; Gupta, PK; Mohapatra, SS; Kumar, A, Tribol. Intl., 119, 38-44, 2018.
7 Y o l d a s , B E , Intl. J. Appl. Glass Sci., 5, 3, 248-54, 2014.
8 Taoda. H, Res. Chem. Intermed., 34, 4, 417-26, 2008.