Upcycling polyethylene plastic waste into valuable molecules

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Researchers develop a one-pot, low temperature catalytic method to turn polyethylene polymers into alkylaromatic molecules.
When we started using plastics about 70 years ago, not much thought -- if any -- was given to the implications of their lifespan and the fact that they can take centuries to decompose. Consequently, as plastics have diversified and become easier to manufacture, the planet is now straddling some 8.3 billion tons of the stuff -- almost every bit of plastic ever produced -- without enough technology or incentives to shrink that growing pile. Plastic is cheaper and easier to produce and throw away than it is to recycle.

UC Santa Barbara researchers Susannah Scott and Mahdi Abu-Omar are poised to shift this decades-old paradigm. How? With a one-pot, low-temperature catalytic method that upcycles polyethylene -- a polymer that is found in about a a third of all plastics produced, with a global value of about $200 billion annually -- into high-value alkylaromatic molecules that are the basis of many industrial chemicals and consumer products. Adding value to what would otherwise become trash could make plastic waste recycling a more attractive and practical pursuit with an environmentally beneficial outcome.

"Here's a potential solution," said Scott, who with her colleagues has now published their research in the journal Science. Their effort, she said, is one in a growing list of possible measures that can be taken to turn plastic's linear, wasteful economy into a more sustainable, circular one.

"This is a demonstration of what can be done," she said.

A Second Life for Waste Plastics

There's no denying that modern existence owes a lot to plastics, from the packaging that keeps foods fresh, to the sterile materials used in medical applications, to the cheap, lightweight parts that go into many of our affordable, durable goods.

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"There are many positive things about plastics that we have to keep in view," said Scott, a professor of chemistry and of chemical engineering at UC Santa Barbara, who holds the UCSB Mellichamp Chair in Sustainable Catalytic…
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