organic chemistry - Why are PTFE and FEP named "ethylene" when they don't have double bonds?

PTFE (Polytetrafluoroethylene) and FEP (Fluorinated ethylene propylene) have the following chemical formulas:

It's been years since I have taken organic chemistry, but I do remember alkenes have double bonds and alkanes have single bonds. Neither of these compounds have double bonds.

Why do these compound names contain "-ene" in them, instead of "Polytetrafluoroethane" or something?

Answer

Polymers follow a slightly different nomenclature system than you are used to in organic chemistry. Instead of naming the polymer after the monomers as they are, we name them after the monomers as they originally were. In other words, a polymer made from ethylene monomers is called polyethylene. Since PTFE and FEP are made from fluorinated ethylene and propylene, we just put "poly" in front of the monomer names. This is despite the fact that after the reaction, the bond order is reduced by one.