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Ladies and Gentlemen, welcome to "Fun with Physical Chemistry". My name is Dr. Lauth
and today we will make a superhydrophobic surface that even repels honey.
A superhydrophobic surface must satisfy two conditions : it must be water-repellent -- hydrophobic
-- and it must be microscopically rough. A water droplet rests on such a surface just like
a fakir on a bed of nails. Both conditions are fulfilled in an ideal
manner by the leaves of the lotus plant , therefore, the effect of superhydrophobicity is also
called the lotus effect. The lotus effect can also be produced artificially
-- just by making a rough water-repellent surface. Maybe the easiest way to create this
type of surface is the depositing carbon soot from a candle or lighter flame, for example
on a glass slice, a beaker or a spoon. We thus obtain a surface on which even honey
droplets don´t stick to. We need: a heat-resistant glass , a candle
or a gas lighter . Light the flame and keep the glass in the
luminous part of the flame . The glass turns black slowly by deposited soot. Once the glass
is homogeneously coated with soot, the superhydrophobic surface is ready. Although our soot surface
is not as stable as the surface of a lotus leaf, both water and honey droplets roll off
of it. With the help of a superhydrophobic knife
water or honey drops can be cut into two smaller droplets.
Thanks for watching. Good bye.