UVabsorbing

UV absorbing refers to substances that absorb ultraviolet radiation and convert it to heat or other non-damaging forms, thereby reducing UV exposure of what they are protecting. These materials are used to shield skin, plastics, coatings, textiles, and packaging from UV-induced damage such as fading, embrittlement, or degradation.

Mechanismically, UV absorbers contain chromophores with conjugated pi-systems that absorb photons in the UV range, typically from about 200 to 400 nanometers. The absorbed energy is then dissipated through nonradiative decay pathways, often as heat, which limits the formation of reactive species that can damage the protected substrate. Some absorbers can fluoresce or undergo structural changes, but effective formulations aim for rapid and safe energy dissipation.

Types of UV absorbers include organic chemical filters and inorganic particulates. Organic filters are carbon- or heteroatom-containing molecules such as benzotriazoles, triazines (including certain octyl triazone-type filters), cinnamates, and benzophenones. Inorganic UV absorbers include metal oxides like zinc oxide and titanium dioxide, which can absorb and scatter UV light. In many products, UV absorbers are combined with stabilizers to enhance photostability and broaden spectral coverage, especially for UVA and UVB protection.

Common applications include sunscreens, where UV absorbers provide skin protection, and materials protection, where they extend the life of polymers, coatings, and textiles. Considerations in selecting UV absorbers include photostability, spectrum of absorption, potential for skin or environmental sensitivity, regulatory status, and interactions with other ingredients.