Adhézió

Adhézió refers to the attraction or binding between dissimilar materials at their interface. It is a fundamental concept in materials science, chemistry, and biology, and is distinct from cohesion, the internal attraction within a single material.

Mechanisms of adhesion include physical interactions, such as van der Waals forces, capillary action, and mechanical interlocking, as well as chemical bonding, including covalent, ionic, and hydrogen bonds. In some systems, diffusion or interdiffusion of molecules across the interface contributes to adhesion. The relative importance of these mechanisms depends on the materials, surface preparation, and environmental conditions.

Factors influencing adhesion include surface energy and cleanliness, surface roughness, contamination, temperature, humidity, and the presence of interfacial films or oxides. Proper surface preparation and compatible adhesive systems are essential to achieve durable bonds.

Adhesion types are often classified as chemical (bonding) adhesion and physical (intermolecular or interfacial) adhesion, sometimes supplemented by mechanical interlocking or diffusion bonding. Adhesives can be liquids, pastes, or elastomeric films; substrates include metals, ceramics, polymers, and biological tissues.

Applications span from industrial coatings and packaging to components in electronics, dentistry and wound care. Bio-inspired adhesives, such as mussel-inspired catechol-based systems, illustrate ongoing research to improve wet adhesion and reversibility.

Assessing adhesion involves tests that measure bond strength, such as peel, pull-off, or scratch methods, under relevant environmental conditions.