Depolymerisation of PTFE to C2F4 (and related low molecular weight fluorocarbons) by vacuum pyrolysis is an energy intensive process; at 510 °C the half-life of conversion of PTFE to monomers has been estimated as ~ 30 min. Although this provides a viable route for reprocessing of PTFE, it is not an effective approach to recycle this material in any other way. In this regard, defluorination holds promise as means to harvest fluorine atoms from PTFE while also creating structurally modified materials. Such an approach could allow waste PTFE to be directly used as a fluorine source in chemical synthesis, providing an alternative (and more circular) approach to current synthetic methods that almost exclusively rely on mineral sources of CaF2 e.g. fluorite. Chemical approaches to the defluorination of PTFE include reactions with Mg in supercritical CO2 above 510 °C, 3 Ca(OH)2 in supercritical water above 650 °C, with zinc powder as a template at 700 °C, or with Mg2Si at 600 °C to form silicon carbide nanoparticles. Low temperature reactions (<100 °C) require strong reductants such as s-block metals in liquid ammonia, lithium-mercury amalgam, sodium naphthalide, benzoin dianion, or alkyl lithium reagents. At the most extreme, destruction of PTFE occurs in military grade pyrotechnic materials such as Magnesium-Teflon-Viton pyrolants. Common to these methods is the proposed formation of inorganic metal fluoride MF(s) (M = Li, Na or K) or MF2(s) (M = Mg, Ca) as a reaction by-product. Only in a limited number of cases, however, has the formation of metal fluorides been confirmed by spectroscopic methods (e.g. powder XRD, XPS, SS Li NMR).