Hydrophile

A hydrophile, from the Greek (hydros) "water" and φιλια (philia) "love," is a molecule or other molecular entity that is attracted to, and tends to be dissolved by water. A hydrophilic molecule or portion of a molecule is one that has a tendency to interact with or be dissolved by, water and other polar substances. This is thermodynamically favorable, and makes these molecules soluble not only in water, but also in other polar solvents. There are hydrophilic and hydrophobic parts of the cell membrane.

A hydrophilic molecule or portion of a molecule is one that is typically charge-polarized and capable of hydrogen bonding, enabling it to dissolve more readily in water than in oil or other hydrophobic solvents. Hydrophilic and hydrophobic molecules are also known as polar molecules and nonpolar molecules, respectively. Some hydrophilic substances do not dissolve. This type of mixture is called a colloid. Soap, which is amphipathic, has a hydrophilic head and a hydrophobic tail, allowing it to dissolve in both waters and oils.

An approximate rule of thumb for hydrophilicity of organic compounds is that solubility of a molecule in water is more than 1 mass % if there is at least one neutral hydrophile group per 5 carbons, or at least one electrically charged hydrophile group per 7 carbons.

Hydrophilic membrane filtration
Hydrophilic membrane filtration is used in several industries to filter various liquids. These hydrophilic filters are used in the medical, industrial, and biochemical fields to filter such elements as bacteria, viruses, proteins, particulates, drugs, and other contaminates. Unlike other membranes, hydrophilic membranes do not require pre-wetting. Hydrophilic membrane fabric can filter liquids and water in its dry state. Although most hydrophilic membranes are used in low heat filtration processes, many new hydrophilic membrane fabrics are used to filter hot liquids and fluids.