Superhydrophobicity and the Lotus Effect

Bryan Cochran

Hydrophobic vs. Hydrophilic

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

waterhydrophilic surface

water

hydrophobic surface

Contact Angle

Angle where water drop makes contact with the surface

Hydrophilic: θ < 90° Hydrophobic: θ > 90° Superhydrophobic: θ > 150°

Polarity and Nano-roughness

Polarity: Opposites repel Polar vs. Nonpolar (ie., Oil and Water)

Nano-roughness: Hydrophobic “tails” Trapped air

waterair

nano-roughened surface

Practical & Real Life ApplicationsLotus Flower

Rose

Water sports

Car Windshields

Skiing

Acknowledgements

http://www.nsec.ohio-state.edu/teacher_workshop/Superhydrophobicity.pdf http://voh.chem.ucla.edu/classes/Superhydrophobic_Surfaces/pdf/Superhyd

ro%20%20Presentation.pdf http://www.iop.org/EJ/article/1468-6996/6/3-4/A05/STAM_6_3-4_A05.pdf?

request-id=0f3098bb-6d01-4fd6-898d-bdede519f8b8 http://en.wikipedia.org/wiki/Hydrophobic http://www.wired.com/science/discoveries/magazine/16-11/st_infoporn# http://inventorspot.com/articles/fioravanti_sees_future_no_windsh_11050