Used as a surfactant in the production of fluoropolymers and fluorinated elastomers, particularly in emulsion polymerization processes. It helps stabilize the polymerization reaction and control particle size. Commonly applied in manufacturing high-performance materials like PTFE (polytetrafluoroethylene), which are used in non-stick coatings, seals, gaskets, and electrical insulation. Due to environmental and health concerns, its use has been largely phased out in many regions and replaced with shorter-chain alternatives.