Used as a fluorosurfactant in fire-fighting foams, particularly in aqueous film-forming foam (AFFF) formulations. It helps suppress flammable liquid fires by forming a film that prevents oxygen from reaching the fuel. Also employed in specialty coatings and polymers to improve surface smoothness, water resistance, and oil repellency. Its strong surface activity allows for effective performance at low concentrations. Due to environmental persistence concerns, its use is being phased out in some regions in favor of shorter-chain alternatives.