Fig. 2: Phosphate-enabled mechanochemical mineralization of PTFE.

a, Screening of various phosphate salts as activators for PTFE. The total yield of released fluoride (both F⁻ and PO₃F²⁻) and their ratio were determined by quantitative ¹⁹F NMR spectroscopy (in 10% D₂O in H₂O using NaOTf as an internal standard). b, Identification of the C/F/P contents of PTFE mix by quantitative ¹³C/¹⁹F/³¹P NMR spectroscopy (in 10% D₂O in H₂O using KOAc or NaOTf as an internal standard) and Raman spectroscopy of water-insoluble black residue after aqueous extraction. Further analysis of PTFE mix by solid-state ¹⁹F/³¹P NMR spectroscopy and powder X-ray diffraction (XRD). ^aActivator stoichiometry was kept constant at 1.25 equiv. P per F. ^bReaction was also performed in a 15-ml zirconia jar with 2 × 6 g zirconia balls affording 98% F_tot release (F⁻:PO₃F²⁻ = 5.5:1). ^cReaction was also performed in a 15-ml zirconia jar with 2 × 6 g zirconia balls affording 99% F_tot release (F⁻:PO₃F²⁻ <1:20). ^dThe observed bands are denoted as D (disordered carbon) and G (graphitic carbon). ^ePrepared mechanochemically from KF and KPO₃. NA, not applicable; ND, not detected.