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Just to add a bit to Ben's excellent answer...

  • A number of fluorinating agents also react with PTFE, $\ce{XeF2}$ and $\ce{CoF3}$ being examples
  • Ben mentioned the reaction of magnesium metal. Typically with metals they must be in intimate contact with the PTFE surface, so molten metals or metals dissolved in anhydrous solvents will react.

The magnesium reaction is of special interest because it serves as the basis of the the thermite flare. A pyrotechnic device commonly used in the countermeasures aircraft use to evade heat seeking missiles. The reaction of metals with PTFE is given by the following equation (I think this is the general description for the reaction of metals with PTFE; I'm suspect of the reaction proposed by Ben involving the formation of poly-perfluoroacetylene).

$$\ce{2Mg + -(C2F4){-} → 2MgF2 + 2C}$$

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 (135 pm) than the $\ce{Si-F}$ bond (160 pm) 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. In Polymers for Electronic & Photonic Application from 2013, the authors state "PTFE is the most chemically resistant polymer known".