Tetrafluoroethylene (PTFE) is a completely fluorinated polymer produced when the monomer tetrafluoroethylene (TFE) undergoes free radical vinyl polymerization. As a monomer, TFE is made up of a pair of double-bonded carbon atoms, both of which have two fluorine atoms covalently bonded to them. Thus the name: “tetra” means there are four atoms bonded to the carbons, “fluoro” means those bonded atoms are fluorine, and “ethylene” means the carbons are joined by a double bond as in the classic ethylene structure.
When TFE polymerizes into PTFE, the carbon-to-carbon double bond becomes a single bond and a long chain of carbon atoms is formed. This chain is the polymer’s backbone. With a ratio of four fluorine atoms to every two carbon atoms, the backbone is essentially shielded from contact. It’s almost impossible for any other chemical to gain access to the carbon atoms. Even if an agent could gain access, the carbon-to-fluorine bonds have high bond disassociation energy, so they’re almost unbreakable. This makes PTFE the most chemically resistant thermoplastic polymer available. PTFE is inert to almost all chemicals and solvents, allowing PTFE parts to function well in acids, alcohols, alkalies, esters, ketones, and hydrocarbons. There are only a few substances harmful to PTFE, notably fluorine, chlorine trifluoride, and molten alkali metal solutions at high pressures.