Download Superhydrophobicity and the Lotus Effect - T

By: Derek McCurry
The Lotus effect refers to the
very high water repellency
exhibited by the leaves of the
lotus plant
 Allows for self-cleaning,
where dirt particles are
picked up by passing water
droplets due to the
architecture of the leaf
surface which minimizes
adhesion
 Main purpose is for
protection against pathogens
(fungi/algae)

Pathogens
Dirt particles

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The leaves of the lotus
plant are
superhydrophobic
Superhydrophobic simply
means the surface is very
difficult to wet due to
the contact angle of the
water droplet with the
surface
Contact angle: ≥ 150˚
Roll-off angle: <10 ˚
Ѳ
Contact angle

The free energy transfer of non-polar solvent to
aqueous solvent is often used to quantify the
hydrophobic effect
O
<O
∆G = H - ∆ TS > O

Hydrophobic effect is entropy-driven at room
temperature (H = zero)

Heat capacity change in transfer is positive, whereas it
is negative for hydrophilic molecule
Cp > O

Nanotechnologists have developed surfaces that can
remain dry and clean themselves similar to the lotus leaf
including;

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Treatments
Coatings
Paints
Roof tiles
Fabrics
Flying insects
 Butterflies
 Dragonflies

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Self-cleaning glass
Protection against concrete corrosion
Anti-snow sticking