Hydrofoba

Hydrofoba, or hydrophobic, describes substances or regions that repel water or have little affinity for it. In chemistry and materials science, hydrophobic materials are typically nonpolar and insoluble in polar solvents such as water. Common hydrophobic substances include hydrocarbons, fats, oils, waxes, and many polymers such as polyethylene and PTFE. Surfaces with high water contact angles are described as hydrophobic, and extremely hydrophobic or superhydrophobic surfaces may exhibit contact angles above 150 degrees.

Molecularly, water molecules reorganize around nonpolar solutes in a way that minimizes disruption of hydrogen bonding, leading to the hydrophobic effect. This entropically driven phenomenon promotes the aggregation of nonpolar groups, aiding processes such as protein folding and the formation of lipid bilayers in cell membranes.

Properties and measurements: hydrophobic compounds have low solubility in water but can dissolve in nonpolar solvents. Wettability, partition coefficients, and contact angle measurements help quantify hydrophobicity. Amphiphilic molecules contain both hydrophobic and hydrophilic regions, enabling emulsification and the formation of micelles.

Applications and relevance: hydrophobic interactions underpin biology, including membrane structure and protein stability. Technologically, hydrophobic materials are used in water-repellent coatings, corrosion resistance, waterproof textiles, and oil–water separation. In chromatography, hydrophobic interaction chromatography exploits these interactions to separate nonpolar compounds.