hydrophile

Hydrophile is a term used in chemistry and materials science to describe substances that have an affinity for water. The word derives from Greek hydro, water, and philos, loving, indicating a tendency to associate with water. Hydrophilic substances are typically polar or ionic and form hydrogen bonds with water molecules, facilitating dissolution or dispersion in aqueous environments.

Molecular and material examples include ions, salts, sugars, amino acids, and many polar organic compounds; polymers such as poly(vinyl alcohol), polyacrylamide, and cellulose derivatives; and surfaces bearing hydroxyl, carboxyl, or amine groups. By contrast, hydrophobic substances repel water and are mainly nonpolar, with poor water solubility. Hydrophilicity often correlates with high water affinity, but the extent can vary with context.

Measurement and behavior: Hydrophilicity is often described by solubility in water and by wettability, which is quantified by contact angle; hydrophilic surfaces have low contact angles (typically less than 90 degrees) and high surface energy. Hydrophilicity can change with pH, temperature, ionic strength, and the presence of other solutes. Some materials are amphiphilic, containing both hydrophilic and hydrophobic parts, and may exhibit different behavior at interfaces or in solutions.

Applications: Hydrophilic properties are important in chromatography (especially hydrophilic interaction chromatography), membranes for water purification, drug delivery where solubility in aqueous media matters, and formulations such as detergents and gels. In biology, many biomolecules are inherently hydrophilic due to charged or polar groups, influencing solubility and interactions.