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Water on hydrophobic surfaces will exhibit a high contact angle. 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 substances from polar compounds. [2]
An example of these amphiphilic molecules is the lipids that comprise the cell membrane. Another example is soap, which has a hydrophilic head and a hydrophobic tail, allowing it to dissolve in both water and oil. Hydrophilic and hydrophobic molecules are also known as polar molecules and nonpolar molecules, respectively. Some hydrophilic ...
The hydrophilic group falls into one of the following categories: [citation needed] charged groups anionic. Examples, with the lipophilic part of the molecule represented by R, are: carboxylates: RCO 2 −; sulfates: RSO 4 −; sulfonates: RSO 3 −; phosphates (the charged functional group in phospholipids) cationic. Examples: ammoniums: RNH 3 ...
The hydrophobic effect depends on the temperature, which leads to "cold denaturation" of proteins. [19] The hydrophobic effect can be calculated by comparing the free energy of solvation with bulk water. In this way, the hydrophobic effect not only can be localized but also decomposed into enthalpic and entropic contributions. [3]
Batch processing a hydrophobic material is a costly and time-consuming technique, and the coatings produced are usually hazy, precluding applications on lenses and windows, and fragile materials. The second class of self-cleaning surfaces are hydrophilic surfaces which do not rely solely on the flow of water to wash away dirt.
Cloth, treated to be hydrophobic, shows a high contact angle. The theoretical description of contact angle arises from the consideration of a thermodynamic equilibrium between the three phases: the liquid phase (L), the solid phase (S), and the gas or vapor phase (G) (which could be a mixture of ambient atmosphere and an equilibrium concentration of the liquid vapor).
Hydrophobic soil is a soil whose particles repel water. The layer of hydrophobicity is commonly found at or a few centimeters below the surface, parallel to the soil profile. [ 1 ] This layer can vary in thickness and abundance and is typically covered by a layer of ash or burned soil.
A drop on a lotus surface, with a contact angle of greater than 146°. A water droplet falling onto a superhydrophobic, elastic surface. In chemistry and materials science, ultrahydrophobic (or superhydrophobic) surfaces are highly hydrophobic, i.e., extremely difficult to wet.