Polyquaternium-11 is a cationic, water-soluble copolymer (quaternized vinylpyrrolidone–dimethylaminoethyl methacrylate) valued for its strong substantivity to keratinous substrates and its ability to form clear, flexible, non-tacky films. In skincare, these films improve slip, laydown, and after-feel, helping reduce tack in humectant-rich systems and enhancing perceived smoothness without heavy occlusion. Because the polymer remains largely on the stratum corneum surface, it is used as a skin-conditioning and sensory aid in lightweight body lotions, toners, and color cosmetics where a uniform film improves rub-in and reduces pilling.

In hair-care, Polyquaternium-11 is a workhorse conditioning/antistatic and styling polymer. Its positive charges electrostatically anchor to the negatively charged hair surface (especially on chemically or physically damaged fibers), decreasing inter-fiber friction, improving wet and dry combability, and delivering styling hold with frizz control through uniform film formation. The polymer is compatible with anionic, nonionic, and amphoteric surfactants, enabling robust deposition from shampoos as well as strong performance in mousses, gels, and sprays. These structure–performance links are well documented for cationic conditioning polymers and are directly reflected in PQ-11 technical literature and INCI references.