Raw bioTAL (left) can be combined with other chemicals and processed into a biorenewable, recyclable PDK plastic (right). Credit: Jeremy Demarteau/Berkeley Lab
Key points:
- Researchers at Berkeley Lab have used bacteria to bring biorenewability to recyclable plastics.
- After four years of trying, researchers successfully engineered E.coli to make biological alternatives for the starting ingredients in an infinitely recyclable plastic.
- The study is the first to demonstrate that the pathway to 100% bio-content in recyclable plastics is feasible.
Researchers at Lawrence Berkeley National Laboratory have successfully engineered microbes to make biological alternatives for the starting ingredients in an infinitely recyclable plastic known as poly(diketoenamine), or PDK.
Unlike traditional plastics, PDK can be repeatedly deconstructed into pristine building blocks and formed into new products with no loss in quality. PDKs initially used building blocks derived from petrochemicals, but those ingredients can be redesigned and produced with microbes instead.
Now, after four years of effort, scientists have manipulated E. coli to turn sugars from plants into some of the starting materials—a molecule known as triacetic acid lactone, or bioTAL—and produced a PDK with roughly 80% bio-content.
“We’ve demonstrated that the pathway to 100% bio-content in recyclable plastics is feasible,” said Jeremy Demarteau, a project scientist on the team. “You’ll see that from us in the future.”
PDKs can be used for a variety of products, including adhesives, flexible items like computer cables or watch bands, building materials, and tough thermosets—rigid plastics made through a curing process. Researchers were surprised to find that incorporating the bioTAL into the material expanded its working temperature range by up to 60 degrees Celsius compared with the petrochemical version. This opens the door to using PDKs in items that need specific working temperatures, including sports gear and automotive parts, such as bumpers or dashboards.
“Our new results are extremely encouraging,” said Corinne Scown, a staff scientist in Berkeley Lab’s Energy Technologies Area and a vice president at JBEI. “We found that with even modest improvements to the production process, we could soon be making bio-based PDK plastics that are both cheaper and emit less CO2 than those made with fossil fuels.”
Those improvements would include speeding up the rate at which microbes convert sugars to bioTAL, using bacteria that can transform a wider variety of plant-derived sugars and other compounds, and powering the facility with renewable energy.