Hydrophobe
For other uses, see Hydrophobia.
Hydrophobe (from the
Greek (hydros) "water" and
(phobos) "fear") in
chemistry refers to the physical property of a
molecule that is repelled by
water. Hydrophobic molecules in water often cluster together.
Hydrophobic or
lipophilic species, or hydrophobes, tend to be
electrically neutral and
nonpolar, and thus prefer other neutral and nonpolar
solvents or molecular environments.
Hydrophobic is often used interchangeably with "oily" or "lipophilic."
The term
hydrophobic interaction (
HI) has been used in the context of several closely-related phenomena to hydrophobic species.
According to
thermodynamics, matter seeks to be in a low-energy state, and bonding reduces chemical energy. Water is electrically polarized, and is able to form
hydrogen bonds internally, which gives it many of its unique physical properties. But, since hydrophobes are not electrically polarised, and because they are unable to form hydrogen bonds, water repels hydrophobes, in favour of bonding with itself. It is this effect that causes the hydrophobic interaction - which in itself is incorrectly named as the energetic force comes from the
hydrophilic molecules. Thus the two immiscible phases (hydrophilic vs. hydrophobic) will change so that their corresponding interfacial area will be minimal. This effect can be visualized in the phenomenon called
phase separation.
Examples of
hydrophobic molecules include the
alkanes, oils, fats, and greasy substances in general. Hydrophobic materials are used for oil removal from water, the management of oil spills, and chemical separation processes to remove non-polar from polar compounds.
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Superhydrophobe*
Hydrophile*
Amphiphiles*
Wetting* Aryeh Ben-Na'im
Hydrophobic Interaction Plenum Press, New York (ISBN 0-306-40222-X)
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Webtool to calculate and plot the hydrophobicity of proteins.
