The demand for more effective methods to recycle as well as reduce plastic waste spurred Northwestern University researchers to advance routes for plastic upcycling. These processes efficiently deconstruct and rebuild polymers for reuse and now include a technique to enhance the effects of an enzyme that breaks down polyester, commonly used to manufacture soda bottles and clothing, into its fundamental components.

The researchers worked with PETase a polyethylene terephthalate-based enzyme that can be synthesized in a laboratory and developed an upcycling process without the use of other solvents. An encapsulating layer composed of industrially scalable random copolymers with hydrophobic components was synthesized toSimulation shows the PETase enzyme (magenta) encapsulated by random heteropolymers. Controlling the polymer composition leads to differences in enzyme binding. Source: Monica Olvera de la Cruz/Northwestern University shield the enzyme from the detrimental effects imposed by elevated process temperatures. The synthesized polymer was then mixed with chemically synthesized enzymes.

“We found that if you put the complex of the polymer with the enzyme together, and close to a plastic, and then you heat it up slightly, the enzyme was able to break it down into small, monomeric units,” said lead researcher Monica Olvera de la Cruz. “In addition to operating in an environment like where it could clean microplastics, our method has protected against high temperature degradation, and one student was able to do the testing.”

Simulations and experiments demonstrated that PETase-random copolymer complexes have enhanced activity on both small molecule substrates and solid PET films.

The development described in the Proceedings of the National Academy of Sciences (PNAS) could help engineer solutions for removing microplastics from rivers and oceans.