Infinitely recyclable plastics may soon become a reality

In a breakthrough discovery that could revolutionize the world of materials, scientists have found a way to engineer microbes to produce ingredients needed for recyclable plastics. This technology has the potential to replace environmentally damaging petrochemicals with sustainable alternatives. 

This research, published today in Nature Sustainability, may drastically change the way we handle plastic waste.

This novel research was conducted through a collaboration among experts from three facilities at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab): the Molecular Foundry, the Joint BioEnergy Institute (JBEI), and the Advanced Light Source. 

Recyclable plastics

The experts aimed to develop biological alternatives to the basic ingredients in an infinitely recyclable plastic known as poly(diketoenamine), or PDK.

Brett Helms, a staff scientist at the Molecular Foundry and the project leader, noted: “This is the first time that bioproducts have been integrated to make a PDK that is predominantly bio-based.”

“And it’s the first time that you see a bio-advantage over using petrochemicals, both with respect to the material’s properties and the cost of producing it at scale.”

Focus of the study

Unlike traditional plastics, PDK can be deconstructed and remolded into new products repeatedly without losing any of its quality. While PDKs were initially developed using building blocks derived from petrochemicals, the team has discovered a way to produce these ingredients using microbes. 

Four years of research and experimentation allowed them to successfully manipulate E. coli bacteria to convert plant sugars into one of the necessary starting materials, a molecule known as triacetic acid lactone (bioTAL). As a result, they were able to produce a PDK with a bio-content of around 80 percent.

Jeremy Demarteau, a project scientist on the team who contributed to biopolymer development, stated with confidence that they are moving toward a completely sustainable solution. “We’ve demonstrated that the pathway to 100% bio-content in recyclable plastics is feasible. You’ll see that from us in the future.”

What the researchers discovered 

PDKs can be utilized in a wide range of products, from adhesives and flexible items like computer cables or watch bands, to construction materials and rigid plastics known as “tough thermosets.” 

Interestingly, the research team found that the integration of bioTAL into the material enhanced its working temperature range by up to 60 degrees Celsius when compared with the petrochemical version. 

This expanded temperature range could make PDKs suitable for use in applications that require specific operating temperatures, including sports gear and automobile parts such as bumpers and dashboards.

Implications of the study

The implications of this research are significant when considering the global plastic waste problem. 

The United Nations Environment Program estimates that approximately 400 million tons of plastic waste are produced globally each year, a figure predicted to exceed 1 billion tons by 2050. 

The vast majority of the 7 billion tons of plastic waste already in existence remains unrecycled and is discarded into landfills or incinerated.

Jay Keasling, a professor at UC Berkeley, senior faculty scientist in Berkeley Lab’s Biosciences Area, and the CEO of JBEI, highlighted the urgency of finding sustainable solutions. 

“We can’t keep using our dwindling supply of fossil fuels to feed this insatiable desire for plastics,” said Professor Keasling. “We want to help solve the plastic waste problem by creating materials that are both biorenewable and circular – and providing an incentive for companies to use them. Then people could have the products they need for the time they need them, before those items are transformed into something new.”

Encouraging results

The findings from this study also draw on a 2021 environmental and technological analysis, which proposed that PDK plastic could be commercially competitive with traditional plastics if produced on a large scale.

Corinne Scown, a staff scientist in Berkeley Lab’s Energy Technologies Area and a vice president at JBEI, is optimistic about the future of PDK plastics. 

“Our new results are extremely encouraging,” said Scown. “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.”

In order to make these leaps in production, advancements would include improving the speed at which microbes convert sugars to bioTAL, utilizing bacteria capable of transforming a broader variety of plant-derived sugars and other compounds, and powering production facilities with renewable energy sources. 

With these enhancements, the future of infinitely recyclable plastics could be within our grasp, promising a cleaner and more sustainable world.

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