Mechanochemical Defluorination of Polytetrafluoroethylene (PTFE) With Base Metals

We report highly efficient mechanochemical redox reactivity between polytetrafluoroethylene (PTFE) and base metals, enabling simultaneous polymer decomposition, fluorination of metals without F₂ or HF, and mechanochemical dealloying. While milling with metals has recently emerged as a mechanochemical platform for PTFE defluorination, most such work has relied on highly reactive, air-sensitive metals, such as alkali elements. We now demonstrate a proof-of-principle for direct and efficient transformation of PTFE into a mixture of sp²-carbon and a metal fluoride by ball-milling with stoichiometric amounts of safe-to-handle, abundant, inexpensive metals such as zinc. The reactivity is applicable to other metals, as shown by aluminum, lead and cadmium, and the process is also extendable into a two-step, one-pot mechanochemical strategy to generate NaF as a recycled fluorine source, along with a ZnO/carbon mixture which can undergo carbothermal reduction to recover zinc, suggesting an opportunity to develop a zinc-based PTFE defluorination cycle. Moreover, ball-milling with PTFE is shown to transform brass into a mixture of copper metal and ZnF₂, providing a proof-of-principle for mechanochemical dealloying of mixed-metal materials using fluoropolymer waste as a reagent. This work introduces a different, mechanochemistry-based paradigm for straightforward, atom-economic, and potentially more sustainable PTFE defluorination, presenting its valorization as a mechanochemical fluorinating agent.