1 of 5

• A number of fluorinating agents also react with PTFE, $$\ce{XeF2}$$ and $$\ce{CoF3}$$ being examples
$$\ce{2Mg + -(C2F4){-} → 2MgF2 + 2C}$$
The formation of $$\ce{MgF2}$$ is extremely exothermic. The heat given off along with the carbon soot provides a new, much hotter, target for the attacking missile to lock onto.
As to whether there is anything more resistant, I suspect that is unlikely. The $$\ce{C-F}$$ bond is shorter than the $$\ce{Si-F}$$ bond and therefore better serves to encase and protect the carbon backbone. While there are some other polymers that have better mechanical or thermal properties, I am not aware of any that have better chemical resistance.