Fluorinated polymers for the circular economy
27.11.2024
Fluorinated polymers are valued in everyday life for their non-stick properties and durability, among other things. However, this becomes a challenge when it comes to recycling them. A research team at the University of Bayreuth has investigated a solution to this problem. Their concept involves chemically transforming fluorinated plastics and thereby recovering the fluorine.
In this interview, Dr. Alex Plajer explains what the new fluorinated polymers are made of, what they could be used for in the future and what opportunities this opens up for the circular economy.
Dr. Plajer, what are the key properties of the new class of fluorinated polymers?
Dr. Alex J. Plajer: The new fluorinated polymers that we are researching are a little more slippery and water-repellent than polyesters without fluorine. However, these polymers are not yet competitive with Teflon, Nafion or similar.
In the study, we looked in particular at the advantage of chemical recycling of fluorinated plastics, as this process is not yet very popular for these plastics. New concepts are therefore needed, and we are currently working on this. With the new concept, we are chemically transforming plastics so that they can ultimately be reused as raw materials.
How do the new polymers differ from previously fluorinated polymers?
Dr. Plajer: The chains of the vast majority of commercialized fluoroplastics (Teflo, Nafion, PVDF) consist only of carbon atoms, and the fluorine depends on these chains. Our plastics, on the other hand, contain ester bridges that make our material degradable and recyclable. Such products are not yet available on the market.
How does this accelerated degradation process work?
Dr. Plajer: We add a very strong base to the fluoroplastics and can thus extract the fluorine. This does not work with water or acids, but only with very strong bases.
What opportunities does the recovered fluorine open up for the circular economy?
Dr. Plajer: The chemical industry wants solutions that are easy to integrate, i.e. they want to adapt their processes as little as possible. In other words, companies need exactly the same basic materials that they already use so that they don't have to adapt the process for producing fluorinated chemicals. The degradation products we generate are in exactly the form that the chemical industry needs them.
What steps still need to be taken before you can really move from the laboratory phase to implementation?
Dr. Plajer: One challenge is certainly the length of the chains: our polymers are not yet long enough. We know that we can manufacture these products and that they offer the possibility of chemical recycling, but the chains are not yet particularly long. We are currently an order of magnitude below what other plastics show that could be commercialized. We therefore need to improve the chemical manufacturing process for polymers.
The second challenge is the price: our products simply cannot yet compete with other plastics, and recycling is also not yet financially viable in some cases because the prices for non-sustainable polymers are so low. The production of our basic building blocks must therefore become cheaper in order to be able to compete.
Where do you see the greatest potential for the use of these new fluorinated polymers in everyday life?
Dr. Plajer: That's a tough question, because we actually like using plastic so much because it is non-degradable, for example for Goretex clothing or Teflon heart valves. I see our products being most useful in short-lived applications, for example as coatings. However, our applications are not yet ready for commercialization. Our main concern is to rethink the idea of recycling and the sustainability concept of fluorine. Because if fluorinated chemicals are so difficult to break down and there is no recycling strategy for them, then these chemicals simply go back into nature and can no longer be recovered. That's why we need to handle them responsibly.
How do you see the future of flourished polymers in terms of environmental compatibility and sustainability, especially when you look at the current criticism of perpetual chemicals?
Dr. Plajer: There are special applications where it will not be possible to replace flourished chemicals: Teflon in a technical seal or Nafion in a fuel cell cannot be replaced with the current state of the art. Then again, there are also applications where these fluorinated substances are unnecessary – in pizza boxes or dental floss, for example. Degradable alternatives could also be used here, which of course still have the advantage of fluorination, but also have the corresponding degradation mechanisms.
Nevertheless, just because a polymer is degradable does not mean that it should be used irresponsibly. When we talk about "degradable plastic bags", we are signaling to society that you can simply dispose of them in the forest. Of course that's not the case! We lose the raw material, the material and all the work that has gone into this product.