oilrepelling

Oilrepelling, or oleophobicity, refers to the property of a surface to resist wetting by oils and nonpolar liquids. An oleophobic surface minimizes the real contact area between a liquid oil and the solid, causing droplets to bead up and roll off rather than spread. This behavior is typically described by the oil contact angle; higher angles indicate better repellency. Oleophobic performance is influenced by surface energy, chemical composition, roughness, and durability, and it can vary with the oil's polarity and surface tension.

Approaches to achieve oil repellency include chemical functionalization with low-surface-energy materials such as fluoropolymers or fluorinated silanes, and the use of micro- or nano-scale roughness to create composite solid–air interfaces (Cassie-Baxter state). These strategies may be used alone or in combination to reduce oil adhesion. Durable oleophobic coatings aim to resist wear and cleaning agents, whereas temporary coatings may provide short-term performance.

Common applications include textiles with oil-repellent finishes to resist stains; consumer electronics screens or casings to reduce fingerprint oil; cookware and packing materials; automotive or industrial components exposed to oily environments. In textiles, standardized tests such as oil repellency ratings evaluate performance against benchmark oils, and a scale (for example 0–12) conveys repellency; tests can vary by region and industry.

Challenges include chemical environmental concerns, notably fluorinated compounds used to achieve low surface energy; ongoing research seeks fluorine-free oleophobic coatings with good durability, breathability for textiles, and resistance to washing. Oil repellency can also depend on oil type, temperature, and surface contamination, complicating universal performance claims.