Why does PTFE still matter? Revisiting its structure–property–performance-applications relationships beyond the PFAS debate

This review aims to present polytetrafluoroethylene (PTFE), its recent syntheses and processes, properties, applications, and its position in the per- and polyfluoroalkyl substances (PFAS) context. It is the most widely produced fluoropolymer, with production volumes increasing every year. In this review, this specialty polymer is described as endowing exceptional characteristics (chemical, thermal, UV, and aging resistance, waterproofness, rheological, mechanical, tribological, surface properties, and moisture vapor permeability). These outstanding features are well explained by numerous studies linking them to their crystallinity and packing structure, which are closely associated with a constantly evolving chemical synthesis process (fluorinated surfactants are no longer used nowadays). Moreover, the high molar mass of PTFE (several million g.mol -1 ) prevents its penetration through the human membrane, in addition to its insolubility in all solvents, non-toxicity, and non-bioaccumulation, showing its safe behavior (i.e., biocompatible) and Food and Drug Administration (FDA) approval. Furthermore, although considered a PFAS, this material meets the 13 Organization for Economic Co-operation and Development (OECD) polymer of low concern (PLC) criteria and, so far, is not subject to regulatory restrictions. Because of such features, PTFE can be used in many advanced applications satisfying stringent requirements (in terms of durability, safety, operational efficiency, and sustainability). Then, PTFE is a must-have material in the medical field and in transportation (aerospace, aircraft, railway, and automotive). It is also essential in electronics, the Internet of Things, clean energy storage and conversion, and other high-tech applications, making it an irreplaceable material in many areas of daily life.