Polytetrafluoroethylene: Synthesis and Characterization of the Original Extreme Polymer

Abstract

This Review aims to be a comprehensive, authoritative, and critical review of general interest to the chemistry community (both academia and industry) as it contains an extensive overview of all published data on the homopolymerization of tetrafluoroethylene (TFE), detailing the TFE homopolymerization process and the resulting chemical and physical properties. Several reviews and encyclopedia chapters on the properties and applications of fluoropolymers in general have been published, including various reviews that extensively report copolymers of TFE (listed below). Despite this, a thorough review of the specific methods of synthesis of the homopolymer, and the relationships between synthesis conditions and the physicochemical properties of the material prepared, has not been available. This Review intends to fill that gap. As known, PTFE and its marginally modified derivatives comprise some 60−65% of the total international fluoropolymer market with a global increase of ca. 7% per annum of its production. Numerous companies, such as Asahi Glass, Solvay Specialty Polymers, Daikin, DuPont/Chemours, Juhua, 3F, 3M/ Dyneon, etc., produce TFE homopolymers. Such polymers, both high-molecular-mass materials and waxes, are chemically inert and hydrophobic and exhibit an excellent thermal stability as well as an exceptionally low coefficient of friction. These polymers find use in applications ranging from coatings and lubrication to pyrotechnics, and an extensive industry (electronic, aerospace, wires and cables, and textiles) has been built around them. South Africa, being the third largest producer of fluorspar (CaF 2 ), the precursor to hydrogen fluoride and fluorine, has embarked on an industrial initiative to locally beneficiate its fluorspar reserves, with the local production of fluoropolymers being one projected outcome. As our manuscript focuses specifically on the homopolymerization of TFE (the starting point for all fluoropolymer industries), it will be of considerable use to start-up companies and other commercial entities looking to enter the fluoropolymer market, as well as to end-user companies. The manuscript commences with a short discussion on the synthesis and production of TFE (both at industrial and laboratory scales), including the safety aspects surrounding handling (because that monomer is regarded as explosive if brought into contact with oxygen due to the formation of peroxides), transport, and storage, and then expands into detailed discussions dealing with aspects such as the various additives used (buffers, chain transfer agents, surfactants, etc.), the solvent environment, and the reaction conditions. A further section reports the properties of PTFE with respect to the polymerization conditions as well as an overview on the specialized techniques used to characterize PTFE. Finally, the applications of PTFE in various fields, ranging from electrical insulation to tribological to medical applications, as well as chemically resistant coatings and pyrotechnics, are discussed.

The Promising Future of Fluoropolymers

“…Since reported in many reviews, [3,5,6,9,15] the syntheses of fluorinated monomers [as tetrafluoroethylene (TFE), vinylidene fluoride (VDF), chlorotrifluoroethylene (CTFE), 3,3,3-trifluoropropene (TFP), hexafluoropropylene (HFP), trifluoroethylene (TrFE)] are not mentioned in this review. They are commercially available and conventional alkenes that contain one or several fluorine atoms born by ethylenic carbon atoms have also been designed on demand for specific applications.…”

Poly(vinylidene fluoride)-based complex macromolecular architectures: From synthesis to properties and applications

“…PVDF is an exceptional member of the fluoropolymer family with the second largest production volume of fluoroplastics after polytetrafluoroethylene (PTFE) [13]. In addition to its extraordinary properties and diverse range of applications, PVDF reveals piezoelectric (when is stretched), pyroelectric, and ferroelectric properties that can be implemented in electronics and energy harvesting devices [14][15][16], haptics and actuators [17].…”

Solid–Liquid Europium Ion Extraction via Phosphonic Acid-Functionalized Polyvinylidene Fluoride Siloxanes

“…To fully take advantage of their unique properties, recent studies have focused on their development and incorporation in different kinds of consumables and products. One of the major members of this polymer family is poly(vinylidene fluoride), PVDF, which is the second most produced fluoropolymer after polytetrafluoroethylene (PTFE) [ 41 , 42 , 43 , 44 ]. This is because PVDF almost displays the same properties as those of PTFE, while its starting monomer, vinylidene fluoride (VDF), is much less dangerous than TFE (not explosive and with a lower toxicity) and also shows a comparable reactivity [ 45 ].…”