New recyclable plastic could solve growing pollution crisis

By Stephen Beech via SWNS

A new infinitely recyclable plastic could solve the growing pollution crisis, according to a new study.

Scientists have engineered microbes to make the ingredients for recyclable plastics – replacing finite, polluting petrochemicals with sustainable alternatives.

Most plastics can’t currently be recycled, and many use finite, polluting petrochemicals as the basic ingredients.

The United Nations estimates that around 400 million tons of plastic waste are produced globally every year, and that number is predicted to climb to more than one billion tons by 2050.

Of the seven billion tons of plastic waste already created, only about 10 percent has been recycled, while most is discarded into landfills or burned.

Now an American research team has successfully engineered microbes to make biological alternatives for the starting ingredients in an infinitely recyclable plastic known as poly(diketoenamine), or PDK.

Project leader Dr. Brett Helms, of the Lawrence Berkeley National Laboratory, said: “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.”

He explained that, 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 trying, the researchers 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 percent bio-content.

Jeremy Demarteau, a project scientist on the team, said: “We’ve demonstrated that the pathway to 100 percent bio-content in recyclable plastics is feasible.

“You’ll see that from us in the future.”

He said PDKs can be used for several products - including adhesives, flexible items such as computer cables or watch bands, and even building materials.

Researchers were surprised to find that incorporating the bioTAL into the material expanded its working temperature range by up to 60 degrees Celsius compared to the petrochemical version.

They say that opens the door to using PDKs in items that need specific working temperatures, including sports gear and automotive parts such as bumpers or dashboards.

Professor Jay Keasling, senior faculty scientist in Berkeley Lab’s Biosciences Area, said: “We can’t keep using our dwindling supply of fossil fuels to feed this insatiable desire for plastics.

“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.”

The study, published in the journal Nature Sustainability, also builds on a 2021 environmental and technological analysis, which showed that PDK plastic could be commercially competitive with conventional plastics if produced at a large scale.

Corinne Scown, a staff scientist in Berkeley Lab’s Energy Technologies Area, added: “Our new results are extremely encouraging.

“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.”