Dilinoleic Acid/Butanediol Copolymer

Dilinoleic acid/butanediol copolymer is a synthetic polymer made by combining dilinoleic acid (a fatty acid derivative) with butanediol (a humectant). It functions primarily as a film-forming agent in skincare formulations.When applied to skin, this ingredient creates a thin, flexible polymeric layer on the surface. It is rarely used as a standalone active and instead appears in formulations where film-forming and texture benefits are desired.

This copolymer works by depositing on the skin surface and cross-linking to form a continuous polymeric film. This barrier helps to occlude moisture and create a smoothing effect, similar in principle to other film-forming agents used in cosmetics.The flexibility of the polymer (due to the butanediol component) means the film can move with the skin rather than becoming rigid or cracking, which is important for comfort and wearability.

This ingredient is typically encountered as part of a complete formulation rather than used in isolation. Follow the instructions of the product containing it. As a film-former, it works best on clean, dry skin and may be layered with other treatments. Reapplication may be needed after cleansing, as the polymer film will be removed during washing.

This ingredient is generally well-tolerated and is unlikely to cause irritation in most skin types. Those with very sensitive skin should patch test first, as with any new product.