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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]
The hydrophobic effect is the observed tendency of nonpolar substances to aggregate in an aqueous solution and to be excluded by water. [ 1 ] [ 2 ] The word hydrophobic literally means "water-fearing", and it describes the segregation of water and nonpolar substances, which maximizes the entropy of water and minimizes the area of contact ...
The hydrophobic effect represents the tendency of water to exclude non-polar molecules. The effect originates from the disruption of highly dynamic hydrogen bonds between molecules of liquid water. Polar chemical groups, such as OH group in methanol do not cause the hydrophobic effect.
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 chaotropic agent is a substance which disrupts the structure of, and denatures, macromolecules such as proteins and nucleic acids (e.g. DNA and RNA).Chaotropic solutes increase the entropy of the system by interfering with intermolecular interactions mediated by non-covalent forces such as hydrogen bonds, van der Waals forces, and hydrophobic effects.
To maintain a hydrophobic surface, the head groups bind closely to the surface, while the hydrophobic micelles stretch far away from the surface. By varying the amount of SAM you coat on a substrate, one could vary the degree of hydrophobicity. Particular superhydrophobic SAMs have a hydrophobic head group binding to the substrate.
Due to the polar nature of the water molecule itself, other polar molecules are generally able to dissolve in water. Most nonpolar molecules are water-insoluble (hydrophobic) at room temperature. Many nonpolar organic solvents, such as turpentine, are able to dissolve nonpolar substances.
Surfactant molecules also aggregate in water as micelles with their head groups sticking out and their tails bunched together. Micelles draw oily substances into their hydrophobic cores, explaining the basic action of soaps and detergents used for personal cleanliness and for laundering clothes. Micelles are also biologically important for the ...