hydrofiele

Hydrofiele is the Dutch term for hydrophilic—describing substances or surfaces with an affinity for water. Hydrophilic materials interact with water via hydrogen bonding, polar functional groups, and sometimes ionic interactions, leading to good wetting and, often, high solubility in water. By contrast, hydrophobic substances repel water and tend to minimize contact with it.

Measurement and design: The degree of hydrophilicity is often expressed by the water contact angle: a contact angle below 90 degrees indicates hydrophilicity; angles below 30 degrees denote strong hydrophilicity. Surface roughness, contamination, and chemical composition can influence measurements. Common hydrophilic groups include hydroxyl, carboxyl, sulfonate, and amine groups. Ionizable groups may become more hydrophilic at certain pH levels.

Examples and applications: Natural hydrophilic materials include cellulose and glass; polymers such as polyvinyl alcohol and polyethylene glycol. Hydrophilic coatings are used to improve biocompatibility and reduce friction in medical devices, contact lenses, and microfluidic devices. In chromatography and separation, hydrophilic interaction liquid chromatography (HILIC) relies on hydrophilic interactions between analytes and the stationary phase.

Advantages and caveats: Hydrophilicity supports protein adsorption and cell adhesion, which can be desirable or undesirable depending on the application. Hydrofiele surfaces can age: exposure to air and hydrocarbons can reduce apparent hydrophilicity; some surfaces become superhydrophilic under certain conditions.