self cleaning coating

1. Hydrophobic Self-
Cleaning Coatings
Husna Zaheer
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2. Contents
Introduction
Synthesis
Durability test
Challenges faced in coating composition
Application
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3. Self-Cleaning Coatings
Specialized surface treatments or materials that possess the ability
to autonomously remove dirt, contaminants, and particles from their
surface.
Designed to maintain the cleanliness and appearance of a surface
Reduce the need for manual cleaning and maintenance
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4. Types
Hydrophilic Hydrophobic
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5. Hydrophobic self-cleaning coatings
Coatings with dual functionality
Hydrophobicity Photocatalytic activity
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6. Why We Need
Extensive exposure to air rain and
pollution surfaces become dirty,
discolored fractured affecting the
Performance
Esthetics
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7. Application
Architectural heritage
Anti icing
Anti biofouling
Fabric and textiles
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8. Routes of
Synthesis
Various routes of
fabrication
Layer by layer
(LBL)
Chemical vapor
deposition
(CVD)
Spin coating
Lithographic
patterning
electrospinning
Sol-gel process
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9. SiO2-TiO2-PDMS Composite coating
Synthesized by sol gel method
TEOS (tetraethyl orthosilicate)
TTIP (titanium tetraisopropoxide)
PDMS (polydimethylsiloxane)
Oxalic Acid
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10. Continue…
Hydrolysis and condensation of TEOS
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11. Continue…
Hydrolysis and condensation of TTIP
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12. Continue…
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Copolymerization of TEOS TTIP and PDMS

13. Coating components
Role of SiO2
 Hardness and Durability
 Surface Roughness
 Reinforcement
 Chemical Resistance
 Hydrophobicity Enhancement
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14. Role of PDMS
Enhance adhesion and durability
Hydrophobicity
Flexibility
UV protection
Reduce the cost of raw material
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15. Role of TiO2
Photocatalytic degradation of organic pollutants
Alcohols, carboxylic acids
Volatile organic compounds, phenol
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16. Photocatalytic Degradation of Organic
Compounds
organic compounds are degraded to CO2 and H20
HC2O4− + •OH → OH− + •COOH + CO2
•COOH + O2 → •HO2 + CO2
•HO2 + •HO2→ H2O2 + O2
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17. Durability Test
Water contact angle measurement
Abrasion resistance test
Chemical resistance test
UV exposure test
Dust and dirt adhesion test
Weathering test
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18. Why These Method and Material
Methods Materials
 The above-mentioned preparation processes are
 complex
 required equipment is demanding
 limits the large-scale preparation and application
 Fluorinated silane coatings are
 expensive
 pollute the environment
 The sol-gel method has been widely used
 simple operation
 easy control of reaction conditions
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19. Challenges Faced in Coating Composition
 Effectiveness Over Time
 Surface Compatibility
 Maintenance and Reapplication
 Variability in Performance
 Environmental Friendly
 Cost
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20. Protection of Architectural Heritage
 commonly used material in historical structures
 limestone
 marble
 other calcareous stones
These surfaces are affected by environmental pollution
acid rain
organic pollutants
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21. Environmental Effect
Acid Rain Cause
Acid dissolution
HNO3 + CaCO3 → Ca(NO3)2 + CO2 + H2O
Surface erosion
H2SO4 + CaCO3 → CaSO4 + CO2 + H2O
Organic Pollutants Cause
Surface staning
Biological growth
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22. Experiment Result
Synthesized coating tested on
Concrete
Portland-limestone
sandstone marble surface
 1 year of outdoor exposure
photocatalytic action of TiO2 remained unaffected
the photocatalytic action was lowered due to the elimination of nanoparticles
from the facial layer
Reduction of TiO2 concentration was more in limestone than in concrete and
sand stone
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23. Thank you
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