Chemists develop radical way to make it easier, more profitable to recycle plastic

The United States generates more plastic trash than any other country - about 46.3 million tons of it - or 287 pounds per person a year, according to a 2020 study. The country's 9% rate of recycling will never keep up. Why so low? The chemistry of today’s plastics makes most difficult to recycle. Even thermoplastics that can be melted down weaken with each re-use. And that leads to the real barrier to recycling – economics. There’s just no profit incentive. But now a group of chemists at the University of North Carolina at Chapel Hill have turned the tables by discovering a method to break down plastics to create a new material that is stronger and tougher than the original – meaning it’s potentially more valuable. 

"Our approach views plastic waste as a potentially valuable resource for the production of new molecules and materials," said Frank Leibfarth, assistant professor of chemistry in the UNC College of Arts & Sciences.  "We hope this method could drive an economic incentive to recycle plastic, literally turning trash into treasure."  Leibfarth and UNC-Chapel Hill professor Erik Alexanian, who specializes in chemical synthesis, describe the approach that could close the loop on plastic recycling in the journal Science. Carbon-hydrogen bonds are some of the strongest chemical bonds in nature. The stability makes it difficult to turn natural products into medicines and challenging to recycle commodity plastics. But by modifying the carbon-hydrogen bonds that are common in polymers, the building blocks for modern plastic used in grocery bags, soda and water bottles, food packaging, auto parts and toys, the life span of polymers could be expanded beyond single-use plastic. With a newly identified reagent that could strip hydrogen atoms off medicinal compounds and polymers, the UNC chemists were able to make new bonds in places previously considered unreactive.