Seminar on

Superhydrophobic Materials

by Hanif sheikh

AMT,MEUVCE, Bangalore

Some of the common natural

Hydrophobic materials are waxes,

oil and fats.

Hydrophobicity comes also from the greek word Hydro(water) and Phobicity (fear) it refers to the physical property of a material that repels a mass of water.

WHAT IS MEANT HYDROPHOBICITY ?

The evaluation of hydrophobicity is made through water contact angle measurements.

A water droplet would be spherical so the water contact angle will be significantly high.

Lotus Effect – Superhydrophobicity

Contact angle: > 150˚

A droplet on a superhydrophobic surface: The droplet touches the leave only in a few points and forms into a ball. It completely rolls off at the slightest declination.

Roughening a hydrophobic surface increases the effective contact angle

Superhydrophobic–contact angle with a drop of water that exceeds 150 degrees

SUPER HYDROPHOBIC COATING

Super hydrophobic technology makes water bounce, it stops it, rolls it off the surface.

The process of coating the surface of a material with hydrophobic property material in order to avoid sticking of liquids on that surface.

This is absolutely unique way of coating unlike conventional whichshrink continuously during drying to produce low porosity films.

Contact Angle Measurement

Goniometer forContact Anglemeasurements

Scanning Electron Microscope• Surface morphology

• Surface structuresize / particle sizeMeasurement

• Surface elementalanalysis

PROBLEMSPipe Corrosion :

$6 –8 billion –transmission pipelines

$276 billion –residential plumbing costs

Bridge Corrosion:Annual cost of US Bridges: $7 billion

Global marine coatings -$4.7 billion

Aircraft Deicing:$5,000 per aircraft

Power Lines :One winter storm -$5 billion

Superhydrophobic coating can be made from many different materials.

Manganese oxide polystyrene (MnO2/PS) nano-composite

Zinc oxide polystyrene (ZnO/PS) nano-composite

Precipitated calcium carbonate

Carbon nano-tube structures

Silica nano-coating

Superhydrophobic Glass Powder

Superhydrophobic Glass Powder

Phase Separating Glass Phase-Separated Spinodal Structure

Heat Treatment Crushed Glass Powder

Acid Etched Powder

Apply Self -Assembled Monolayer

(SAM)

Product(s)Coatings Applications

Anti-fouling

Anti-condensation

Anti-friction

Anti-ice

Anti-clotting

Anti-corrosion

Tested Applications

Coated Cables Uncoated Cables

Tested Applications

Uncoated Reference Sample Modified SH Coating

APPLICATIONS

• A primary purpose of hydrophobic coatings such as polytetrafluoroethylene(PTFE) is to act as a barrier against water commonly seen in automobiles.

• Used in fabrication on metallic nano rod to prevent icing.

• Its is widely used in aerospace industry for providing anti-icing coating on the surface of the aeroplane .

• Hydrophobic self cleaning glasses are installed in traffic sensor control unit.

• We induce hydrophobic recovery after plasma treatment, a physical contact treatment (PCT) .

self-cleaning, low adhe- sion and drag reduction in nature.

The development of superhydrophobic and self-cleaning surfaces is important for basic research as well as various applications, such as anti-biofouling paints for boats, antisticking of snow for antennas and windows, self-cleaning windshields for automobiles, microfluidics, lab-on-a chip devices, metal refining, stain resistant textiles, anti-soiling architectural coatings, dust-free coatings on building glasses and so on.

It will be great challenge for the material scientists to fabricate permanent or semi-permanent superhydropho- bic surfaces for its use in commercial products.

Conclusions

THANK YOU