# Is there ANY chemical that can destroy PTFE, or Teflon?

Polytetrafluoroethylene was discovered by accident. It now is an important material in the industry mainly because of its extremely high bonding energy, which prevents corrosion, halts reaction, and reduces friction (yeah carbon-fluorine bonds!)

And people would have definitely put it to the test, making it contain some of the most vicious and chemically diabolical substances ever created. There is a whole HOST of items it can contain that some chemists have gone so far as to say they were 'evil':

1. Dioxygen Difluoride
Known as the gas of Lucifer, there is a whole list of people blown up and killed while just trying to work with one of its components, fluorine. It ignites stuff at temperatures that most of the stuff that we breathe in would be in liquid form. No one really knows about its atomic structure (obviously).

2. Fluoroantimonic Acid
With a staggering pH of -25, it chews through stuff you might not even believe could be corroded; like wax or glass. It can even strip hydrogen off of methane

...There are a lot of other chemical demons it can contain, but this is not the point. Let this suffice: Chemical Resistance Comparison (Spoiler: Fluorine is good at this corrosion thing.)

With this kind of hyper-resistance to about anything chemically destructive, is there anything that can destroy Teflon through only chemical means? A chemical that reacts exothermically to release heat, which melts the PTFE does not count. You get the drift.

Also, I am very curious as to whether there is anything more resilient than Teflon? Polytetrafluoroethylene is made of many carbon-fluorine bonds in series. However, carbon-fluorine is second only to the Si-F bond. Is there an "overclocked" Teflon made of silicon-fluorine bonds that is even stronger?

EDIT: Now I know that some, but very few, solvents can make a mark on Teflon; but my question has not been answered: Is there any more resistant substances?

(More Teflon bragging: Here. Take that aqua regia)

• – Mithoron Jul 19 '15 at 22:25
• possible duplicate of Are PTFE stir bars resistant to all lab solvents? – Mithoron Jul 19 '15 at 22:28
• FWIW, Wikipedia claims that chlorine trifluoride (your standard go-to stuff for making things, that don't normally burn, burn) reacts with teflon. Frankly, I'm surprised by your claim that FOOF doesn't, since it's generally even nastier. Maybe you need to keep the temperature low enough? – Ilmari Karonen Jul 20 '15 at 3:31
• Just some personal experience... a PTFE dish was irrevocably stained (scrape it and it was still brown) by cooking it in a mixture of jet fuel and m-toluidine. So whatever happened, we definitely didn't have a cleanable PTFE dish any more - but it happens (and they were not used again for such a test). (Of course it could have absorbed the solution like a sponge - but I wouldn't know how they could be separated.) – DetlevCM Jul 20 '15 at 12:31
• @Hyperluminal - "With a staggering pH of -25, it chews through stuff you might not even believe could be corroded; like wax or glass. It can even strip methane of hydrogen." ... I thought you said fluoroantimonic acid is an acid. If it's an acid, how can it strip methane of protons? – Dissenter Aug 17 '16 at 16:15

• 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 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 author states, "PTFE is the most chemically resistant polymer known".

• I like your reaction better with reducing metals better. It explains why white PTE-coated magnetic stirbars begin to turn black after repeated Grignard or dissolving metal reactions. – Ben Norris Jul 20 '15 at 0:20

Corrosion Resistant Products, Ltd., with the help of Dupont, has established this source of information on what can and cannot eat teflon.

Here's a list:

• Sodium and potassium metal - these reduce and defluorinate PTFE, which finds use in etching PTFE
• Finely divided metal powders, like aluminum and and magnesium, cause PTFE to combust at high temperatures

These reactions probably reduce PTFE in a manner that starts:

$$\ce{(CF2CF2)_{n} + 2Na -> (CF=CF)_{n} +2NaF}$$

• The world's most powerful oxidizers like $\ce{F2}$, $\ce{OF2}$, and $\ce{ClF3}$ can oxidize PTFE at elevated temperatures, probably by:

$$\ce{(CF2CF2)_{n} + 2nF2 -> 2nCF4}$$

Similar things can occur under extreme conditions (temperature and pressure) with:

• Boranes
• Nitric acid
• 80% NaOH or KOH
• Aluminum chloride
• Ammonia, some amines, and some imines

I am aware that this answer does not describe a ‘chemical that can destroy PTFE’. However, since you are also asking ‘is there anything that can destroy Teflon through only chemical means?’, and in order to complete the other answers, I would like to add that PTFE can be easily destroyed by means of radiation chemistry. (Radiation chemistry is the study of the chemical effects of radiation on matter. It is not to be confused with radiochemistry, which is the chemistry of radioactive materials.)

PTFE is exceptionally sensitive to radiation. PTFE experiences significant damage at lower radiation exposure levels than other polymers. In general, PTFE is considered usable without any significant restrictions only for absorbed doses of up to $100\ \mathrm{Gy}$.

The general radiation effects on polymers are formation of gas, cross-linking of polymer chains, and scission of polymer chains. In contrast to most other polymers, all hydrogen atoms in PTFE are substituted by fluorine atoms; therefore, the elimination of hydrogen or hydrogen fluoride and the corresponding formation of double bonds do not occur. The elimination of fluorine due to $\ce{C-F}$ bond break is possible; however, since $\ce{C-C}$ bonds are clearly weaker than $\ce{C-F}$ bonds, $\ce{C-C}$ bond break predominates. Therefore, the primary effect of radiation on PTFE is the scission of the polymer chain (breaking of the large polymer molecule into smaller parts). Due to the absence of π-electrons, the excited states are not particularly stabilized, resulting in high radiation-chemical yields. Because of the absence of unsaturated bonds, the absence of functional groups that can be easily eliminated, and the general chemical inertness, PTFE cannot be cross-linked like an elastomer. Therefore, the scission of the polymer chain is not compensated for by the formation of new bonds. With advancing chain scission, the molar weight of the polymer is dramatically reduced from an initial value of about $6\times10^6\ \mathrm{g\ mol^{-1}}$. It is divided by $4$ after $250\ \mathrm{Gy}$ exposure and by about $20$ for a dose of $1000\ \mathrm{Gy}$.*

The effect of molecular weight reduction is primarily on mechanical properties. Tensile strength is reduced by $25\ \%$ after $500\ \mathrm{Gy}$ exposure and by $50\ \%$ for a dose of about $900\ \mathrm{Gy}$. For doses above $1500\ \mathrm{Gy}$, imminent material failure has to be assumed because of a brittle behaviour with unstable crack propagation.

If possible, PTFE components should be avoided in high radiation environments (nuclear power plants, nuclear fuel cycle facilities, irradiation facilities, or particle accelerators).

• The irony here is that one of the earliest uses of PTFE was as valve coatings in uranium enrichment facilities. – Mark Jul 20 '15 at 22:47

A PTFE surface can be chemically altered for bonding to other materials by solvated electrons in liquid ammonia (leaving the bulk PTFE intact). Classically alkali metals have been used for this, but a more controlled reaction is obtained from an electrolytically generated magnesium solution. See http://pubs.rsc.org/en/content/articlelanding/1996/cc/cc9960000403.

It is a minor point to an excellent question and post, but are you considering pH and Hammett Acidity Function as the same thing for superacids here? The molarity of protons required to have a pH of -25 is pretty mind-boggling. I think given the common confusion over pHs under 0 it's an important distinction to point out. Without doubt H2FSbF6 is going to pH somewhere in the negatives in many, many hydrofluoric diluted concentrations, but the only real way to rate with specificity it is with Hammett. And it could certainly be found to be in the range you ascribe its pH to.

As far as materials that can chemically attack PTFE, in my work in the agrichemical manufacture industry I've yet to come across one, however I find it interesting that when designing piping for concentrated HCl PTFE is consistently rated a 'good' choice for gasketing and EPDM is rated 'better.' Is there a worry with prolonged concentrated HCl exposure? I'm answering a question with a question and my name isn't Socrates, so I apologize, but it is something I've wondered in passing.

• Welcome to the chemistry stack exchange . Please take the tour. chemistry.stackexchange.com/tour If you post the question as a second question you are more likely to get an answer. Your point seemed to be well taken so I see no issue with leaving this as an answer. – Agriculturist Aug 17 '16 at 16:03

Similar polyflourines have been decomposed by ball-milling PTFE with dry potassium hydroxide. There s an interesting article by Zhang et al. [1] which is really informative and makes me thing that PTFE would respond similarly. Everything breaks down to the mineral elements with no nasty interims formed. The energy and pressure of the steel balls smashing the KOH into the polyflourines causes the reactions to go with no aqueous stage needed. It could be the answer to reducing the PTFE waste impact on the environment.

### References

1. Zhang, K.; Huang, J.; Yu, G.; Zhang, Q.; Deng, S.; Wang, B. Destruction of Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoic Acid (PFOA) by Ball Milling. Environ. Sci. Technol. 2013, 47 (12), 6471–6477. https://doi.org/10/gf5w4f.

HF can attack PTFE slowly, but once it gets going, it can self-propagate. The PTFE decomposes to more HF, which then attacks itself. I find it ironic that PTFE is listed as a container for hydrofluoric acid, but the PTFE is slightly permeable to the acid.
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