1. Superhydrophobicity and the Lotus Effect
Bryan Cochran

2. Hydrophobic vs. Hydrophilic
water
Hydrophobic:
“fear of water”
Refers to the degree that water “beads up” on a surface
Hydrophilic:
“love of water”
Refers to the degree that water “wets” or adheres to a surface
hydrophobic surface
water
hydrophilic surface

3. Contact Angle Angle where water drop makes contact with the surface
Hydrophilic: θ < 90°
Hydrophobic: θ > 90°
Superhydrophobic: θ > 150°

4. Polarity and Nano-roughness
Opposites repel
Polar vs. Nonpolar (ie., Oil and Water)
Nano-roughness:
Hydrophobic “tails”
Trapped air
water
air
nano-roughened surface

5. Practical & Real Life Applications
Water sports
Lotus Flower
Rose
Car Windshields
Skiing

6. Acknowledgements