Researchers at the University of Konstanz have developed a new plastic that is highly stable, biodegradable, and readily recyclable.
How can plastics be designed so that they maintain their useful properties while also being more easily recyclable? Chemist Stefan Mecking and his research group at the University of Konstanz are focused on studying eco-friendly solutions for plastics. In their recent paper in the international edition of Angewandte Chemie, the team introduces a new polyester that exhibits material properties that are suitable for industrial use and environmentally responsible.
Normally hardly compatible
Plastics are made of long chains of one or several chemical basic modules, so-called monomers. Plastics distinguished by high crystallinity and water repellency, therefore mechanically highly resilient and stable, are widely used. A well-known example is high-density polyethylene (HDPE), whose basic modules consist of non-polar hydrocarbon molecules. What may on the one side be advantageous properties for applications can also have adverse effects: It is very energy intensive and inefficient to recycle such plastics and recover the basic modules. Also, if such plastics leak into the environment, the degradation process is extremely long.
To overcome this supposed incompatibility between the stability and biodegradability of plastics, Mecking and his team insert chemical “breaking points” in their materials. They already showed that this greatly improves the recyclability of polyethylene-like plastics. However, good biodegradability is not automatically guaranteed. “Plastics often gain high resilience because they are ordered in densely packed crystalline structures,” Mecking explains: “Crystallinity in combination with water repellency usually strongly decelerates the biodegradation process, as it impairs the microorganisms‘ access to the breaking points.” However, this does not apply to the researchers’ new plastic.
Crystalline and yet compostable
The new plastic, polyester-2,18, consists of two basic modules: a short diol unit with two carbon atoms and a dicarboxylic
Reference: “Biodegradable High-Density Polyethylene-like Material” by Marcel Eck, Simon Timm Schwab, Taylor Frederick Nelson, Katrin Wurst, Steffen Iberl, David Schleheck, Christoph Link, Glauco Battagliarin and Stefan Mecking, 8 December 2022, Angewandte Chemie.
DOI: 10.1002/ange.202213438
