Researchers Develop a Plastic That Digests Itself

A team led by researchers at the University of California San Diego have developed a type of biodegradable plastic that can begin digesting itself when it makes contact with soil or compost. 

The soft plastic material is a type of thermoplastic polyurethane (TPU), commonly found in memory foam products and soft products like cushions, floormats and even shoes. The updated TPU that researchers created includes spores of Bacillus subtilis. The bacteria remains dormant in the plastic until it reaches compost, where it interacts with nutrients and begins to break down the plastic.

“It’s an inherent property of these bacteria,” Jon Pokorski, co-author of the study and a nanoengineering professor at Jacobs School of Engineering at UC San Diego, said in a statement. “We took a few strains and evaluated their ability to use TPUs as a sole carbon source, then picked the one that grew the best.”

The research team combined the bacteria and the TPU in a plastic extruder, where the materials were melted and mixed together to create the pieces of biodegradable plastic.

Then, researchers tested the plastic by placing strips of it in compost. The team set up two compost areas with the same temperature, 37 degrees Celsius, and similar humidity levels of 44% to 55%. One area was sterile while the other was microbially active. 

The results showed that the plastic reached over 90% biodegradation in a 5-month timeframe in both compost types. The researchers published their findings in the journal Nature Communications.

“What’s remarkable is that our material breaks down even without the presence of additional microbes,” Pokorski said. “Chances are, most of these plastics will likely not end up in microbially rich composting facilities. So this ability to self-degrade in a microbe-free environment makes our technology more versatile.”

Next, the researchers plan to continue to determine the feasibility of scaling up this development while also finding ways to speed up the biodegradation time. They also hope to try this method on other types of plastics.

While the development could help reduce the impact of new plastic products in the future, many scientists still underscore the importance of reducing plastic production altogether.

Steve Fletcher, director of the Revolution Plastics Institute at the University of Portsmouth who was not involved in the study, told BBC News, “Care must be taken with potential solutions of this sort, which could give the impression that we should worry less about plastic pollution because any plastic leaking into the environment will quickly, and ideally safely, degrade. Yet, for the vast majority of plastics, this is not the case.”