Q&A: Michiel Dusselier on creating green plastics

Summary

Postdoctoral researcher Michiel Dusselier has developed a new, cost-efficient and sustainable method of producing PLA, one of the best-known bioplastics

Building blocks

Michiel Dusselier (pictured) is a postdoctoral researcher in bioscience engineering at the University of Leuven. He’s developed a cost-efficient and greener method of producing PLA, one of the best-known bioplastics, or plastics derived from renewable sources such as vegetable fats and agricultural by-products.

First of all: what’s the problem with the current method of production for PLA?

The current production process is expensive because there are lots of intermediate steps. First a low quality PLA is made from lactic acid that is then broken down again to yield lactide molecules – the building blocks of PLA. Those building blocks are then polymerised to give a good quality PLA. Part of the lactic acid feedstock, however, is wasted in this process, as it needs certain conditions – high temperatures, costly vacuum pressures – that create by-products. In short, the current route presents an expensive detour that’s inefficient.

What’s different in your method?

It’s a radically new process that only takes one step to make lactide from lactic acid, thanks to a zeolite catalyst. This has many advantages: It allows us to skip a step, needs mild temperatures and pressure conditions and has minimal by-products. The purity of the lactide building blocks is very high, eliminating the need for additional expensive purification. The process is also – in theory – waste-free, as the few by-products formed can be recycled, and the zeolite is reusable.

How biodegradable is PLA? Can I just drop a cup made from it in the street?

No. Chemically speaking, perhaps, but it would still take a very, very long time to decompose. However, PLA is easily degradable via industrial composting. Also, if collected and sorted, it can readily be recycled into lactic acid, which can be used again to make new PLA. It’s very hard to do this with classic plastics.

The degradable aspect is also useful in medicine. For example, there are stitches made from PLA that are gradually absorb into the body. Furthermore, PLA is renewable, as the lactic acid is made from sugars from plants, not from oil or gas.

Can your method be applied to other plastics?

Our technology is indeed not only applicable to PLA, but also to other polyester plastics. As such, the process can facilitate the synthesis of underexplored and even new renewable polymer building blocks. These can lead to novel polyester plastics with different and enhanced properties. We hope polymer researchers worldwide will pick up on our technique, as until now, it’s been very hard to make some of these building blocks in the lab.