1. Highly Robust and Durable Superhydrophobic Coating through Soft Thermo-molding of Perfluorinated Thermoplastics for Self-cleaning and Anti-icing
Li Wanbo
Supervisor: Prof. Ren Kangning
Co-supervisor: Prof. Ong Beng

2. Superhydrophobicity (SH) – Bioinspired
b. Salvinia
SH leaves with hydrophilic pins
collect air underwater
a. Peanut
SH leaves
self-cleaning
c. Lupin
SH leaves with superhydrophilic channels
collect water in very dry and hot media
d. Butterfly
structural color of wings
warn predators
f. Candida
Superoleophobic
surface structures
anti-wetting
e. Water strider
slip on water
g. Gecko
walk on vertical surfaces
Superhydrophobicity is a natural ability that is found on the skins of many live beings, such as lotus leaf and water strider
h. Cicada
anti-bacterial and self-cleaning wings
Also, moth/mosquito
anti-reflective and anti-fogging eyes
J Mater Chem A Mater energy Sustain, 2014, 2,

3. potential applications and impact of SH
5 ℃
-10 ℃
Superhydrophobic coating are drawing much attention recent years in many areas such as……
Textiles
Anti-corrosion
Floating properties
Optical devices
Anti-fouling
Anti-icing
Anti-bacteria
Oil–water separation

4. Current methods for preparing SHS and their limitations
Applied Surface Science 257 (2010) 1540
Applied Physics A, 2015, 119(1): 75
Etching or anodizing substrate Al Cu
Journal of Adhesion Science and Technology 23 (2009) 1215–1237
Science, 2015, 347(6226):
Crystallizing or embedding nanoparticles
Energy/reagent-demanding; unstable and not hydrophobic enough
Fragile structures could not stand mechanical/chemical/ thermal disturbance
Expensive and unsuitable for large-scale application
Loss of liquid layer
Oil or water Lubricant film
Nature, 2011, 477(7365): 443
ACS applied materials & interfaces, 2013, 5(10): 4026

5. Feasible to process, low cost, widely used in our life
Plastic—materials play an essential role in social evolution and civilization in modern times
In the present work, we turn to polymers to generate superhydrophobic coating, because they are feasible to process and low cost.
Feasible to process, low cost, widely used in our life

6. Hypothesis The fluorine of Teflon prefer their own kind, drawing to each other, while repelling other kind of molecules, i.e. water.
Teflon Material
Extremely low surface energy
Self-lubricating,
Extremely inert,
Stable from -200 to 250 °C,
Anti-sticking.
Performance of coating?
Repellent to liquid
Anti-abrasion,
Chemically robust
Thermally stable
Anti-fouling
In our work, we use Teflon materials to fabricate SH coating. Perfluorinated polymer often refer to Teflon. The carbon-fluorine bonds in Teflon are very strong, and pack closely to protect the carbon atoms from other molecules to enable substitution reaction.

7. Fabrication of SH Teflon surface.
The two steps involved in the method are both cycled to generate soft intermediate master and the daughter replica.
A continuous piece of engineered Teflon surface not only provides solid surface structures, but also protects the bonding layer from external invasion.

8. water droplets bouncing on bended Teflon SHS

9. Bonding Teflon with substrates.
we did water contact angle measurements after the Teflon coating was peeled off forcibly
oth glasses and fabrics bonded by Teflon could not be separated, instead, they were broken along the side of the bonding area; also there were Teflon residuals on the side of the bonded area on the aluminum plate.
Displacement

10. Fabrication of Teflon SH coating on desired substrate.

11. 3.4. Mechanical robustness.
100 thousand times along both its front and back sides
1500 g on a 1-cm2 area, = 3×ground pressure of a adult.
Abrasion under weight ( g) for 150 times

12. Chemical stability
Outdoor environments: rainy for 4 days and sunny for 3 days; temperature ranged from 30 to 35 ℃
Strong chemicals

13. Anti-fouling ability
Micro particles nanoparticles

14. Icing problems Transportation Energy Industry Daily life Communication
Power lines
Industry
Daily life
Superhydrophobic Surface coatings have wide arrange of applications in many areas

15. Mechanism of Anti-icing using SH coating
Timely removal of impacting water droplet;
Delay ice formation,
Weaken the adhesion strength between the ice and the substrate.
Superhydrophobic coating could be an effective solution to icing problem.
Despite these efforts, the nucleation of ice on superhydrophobic surface is still unknow.

16. Anti-icing setup
Three modulus: dehumidification, supercooling, and icing.

17. De-frosting by impacted super-cooled water droplets

18. Conclusion
Developed robust SH coatings composed of a continuous piece of micro/nano structure made from Teflon by soft thermo-molding;
Robust against severe thermal, mechanical, chemical, and photo-radiation invasions,
Provides reliable bonding strength between various substrates, e.g. fabric, glass, and metal.
the SH coatings are promising for anti-icing even in humid environment.

19. Thank you