ETH research team develops energy-efficient and fast PEF production method

Rosenboom is a fresh PhD graduate in the research group of ETH professor Massimo Morbidelli at the Department of Chemistry and Applied Biosciences. "The question is how we can reduce the negative environmental impact of plastic while maintaining its benefits for our society," he added.

Massimo Morbidelli's group at ETH Zurich university for science and technology is investigating a promising bioplastic called polyethylene furanoate (PEF). PEF is chemically very similar to PET but consists of 100% renewable raw materials such as forestry and agricultural wastes. PEF bottles, for example, require less material, are lighter and more stable than their PET competitors and make beverages last longer. Although PEF is not biodegradable, it can be incinerated in an environmentally friendly manner besides recycling, as no additional CO2 emissions are produced.

The fact that PEF has not yet been able to establish itself on the market is primarily due to its time- and energy-intensive production. ETH doctoral students Jan-Georg Rosenboom and Peter Fleckenstein, together with ETH professor Giuseppe Storti, have now developed a method that could enable the commercial breakthrough of PEF. Their research results were published in the journal Nature Communications.

"Our method reduces production time from several days to a few hours. In addition, discoloration in the end product can be avoided in contrast to previous processes," says Jan-Georg Rosenboom and explains: "Instead of making the usual "rope-like" polymer chains with two end points react, we first tie rings from the latter, which thus have no ends anymore. These rings can then be polymerized to PEF much more quickly and in a controlled manner. This is because no chemical by-products are produced and have to be removed, when the rings are opened and connected to form the final long "polymer rope". The very fast reaction within minutes enables PEF products that are superior in material properties to PET and reduces energy requirements.”

PEF bioplastics are indistinguishable from conventional PET on the outside. (Photograph: ETH Zurich / Jan-Georg Rosenboom)

In addition, the method of ring opening allows a precise adjustment of the product quality, which was not possible with the previous production process. Thus, the new method could also be interesting for the production of other types of plastics and bioplastics. Due to its good material properties, the PEF could possibly also replace multilayer materials that are difficult to recycle.

Currently, the scientists are working with Sulzer to investigate how the new process could be implemented in industrial mass production. Despite the many advantages offered by PEF, it cannot solve all existing problems on its own, says Rosenboom, stressing: "Education and an improved awareness of how to handle plastics will continue to be crucial in order to stop the increasing environmental pollution. However, progress in manufacturing and recycling technologies will facilitate the transition towards a sustainable society".

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Reference:Rosenboom JG, Hohl DK, Fleckenstein P, Storti G, Morbidelli M: Bottle-grade polyethylene furanoate from ring-opening polymerisation of cyclic oligomers. Nature Communications, 24 July 2018, doi: 10.1038/s41467-018-05147-y