German researchers make a polystyrene that is half plant-based and built to break down

Researchers led by the Helmholtz-Zentrum Hereon in Germany have developed a version of polystyrene that is about half plant-based, can be made with less energy and is designed to break down at the end of its life, Hereon said. The study was published in the journal Chem Circularity.

Polystyrene is made in huge amounts and rarely recycled

Nearly 20 million tonnes of polystyrene are produced each year, for protective packaging, building materials and laboratory Petri dishes. It is mostly made from crude oil, is rarely recycled because new material is often cheaper, and resists breaking down in the environment.

Sugar-derived ingredients and a microwave

The team added itaconic anhydride, a compound that can be made by fermenting plant sugars, so that the new plastic contains about 50% bio-based material. Instead of heating reaction vessels, they used microwaves to drive the reaction, which is faster and uses less energy.

They also built in a compound called DOT, which acts as deliberate breaking points in the polymer. At the end of its use, the material can be chemically split into small fragments for further processing, and bacteria can digest those fragments, unlike conventional polystyrene.

“The new polymer was developed according to the design-for-degradation principle, meaning it is engineered for controlled breakdown at the end of its service life.” — Professor Francesca Toma, Director, Institute of Functional Materials for Sustainability, Hereon

So far, coin-sized Petri dishes

Early tests show the material works in standard injection-moulding machines. The team has so far made miniature Petri dishes about the size of a one-euro coin, and preliminary tests with human stem cells suggest it performs as well as commercial polystyrene for cell culture.

It is still a lab-scale result, with work from BTU Cottbus-Senftenberg, Freie Universität Berlin and Helmut Schmidt University. Other teams are tackling plastic from the recycling side, such as a sensor that verifies recycled content in plastic.