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Hydrophobic

Reviewed by Peter MaciosCheckmark
Last updated: May 22, 2024

What Does Hydrophobic Mean?

Hydrophobic refers to the property of a substance that repels water. It means lacking affinity for water, or tending to repel or to not absorb water. Hydrophobic molecules tend to be non-polar molecules and group together. Oils and fats, for example, are hydrophobic.

Hydrophobic materials often do not dissolve in water or in any solution that contains a largely aqueous environment. These materials are often used to remove oil from water, to manage oil spills, and in chemical separation processes that require the removal of non-polar substances from polar compounds.

Hydrophobic may also be known as hydrophobicity. The opposite of hydrophobic is hydrophilic, which means water-loving. Surface-active agents contain both hydrophobic and hydrophilic groups on the same molecules.

Hydrophobic surfaces decrease corrosion rates and are therefore used in corrosion resistance.

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Corrosionpedia Explains Hydrophobic

Hydrophobic substances cannot dissolve in water. Chemical groups that tend to make substances hydrophobic include -CH2– chains and rings (hydrocarbons). These substances lack the ability to hydrogen bond, and their surface free energy is relatively low. Water does not tend to wet hydrophobic surfaces; rather, the droplets stay beaded up with high values of contact angle.

Hydrophobic molecules, called hydrophobes, repel bodies of water and, owing to the fact that they are non-polar, they attract other neutral molecules and non-polar solvents. Natural hydrophobes include alkanes, fats, and oils.

Hydrophobic and super-hydrophobic materials possess a set of unique functional properties, namely:

Material scientists have been working on using various chemicals to alter the surface properties of surfaces to make them hydrophobic. To provide glass with a hydrophobic characteristic, silanes are often used. Similar hydrophobicity concepts have been applied in paints, coatings, and textiles.

For example, the super-hydrophobic coatings on 316L stainless steel exhibit an excellent corrosion resistance in chloride-containing solution at room temperature. Corrosion can be protected by making the surface hydrophobic; hydrophobic surfaces have been found to strongly decrease the corrosion rate of concrete surface. Hydrophobic surfaces are also important in protecting surfaces from water damage and stains.

Hydrophobic coatings are mainly used in sealed environments that are not exposed to wear or cleaning, such as electronic components and air conditioning heat transfer fins, to protect them from moisture and to prevent corrosion.

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Synonyms

Hydrophobicity

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