Interdisciplinary team of researchers explores new methods of plastic upcycling

CATEGORIES: News, Research
Discarded plastic containers piled up.

by Mike M. McMahon, Institute for Sustainability and Energy at Northwestern

By the year 2050, the World Economic Forum projects that plastic waste in the world’s oceans will outweigh fish pound for pound.

Plastic is everywhere: in our homes, offices, schools. The material is cheap, versatile, lightweight, and durable. In fact, it is so durable that, unlike many other kinds of materials, most types of plastic do not decompose. This raises a host of environmental and human health concerns as plastic particles can drift throughout the environment indefinitely, often traveling up the food chain and ending up on our dinner plates and in our drinking water.

Now a team of scientists from the multi-institutional Program on Plastics, Ecosystems, and Public Health (PEPH) at the Institute for Sustainability and Energy at Northwestern University (ISEN) is taking an innovative approach to tackling the challenge of plastic waste. The new initiative, known as the Institute for Cooperative Upcycling of Plastics (iCOUP) and housed at Ames National Laboratory, is made possible by a recent $12.8 million research award from the U.S. Department of Energy’s transformative Energy Frontier Research Center (EFRC) program.

“iCOUP is highly interdisciplinary. We’ve brought together catalysis scientists, material scientists, polymer scientists, theorists, and spectroscopists to try to tackle the problem of selective conversion of plastics—specifically polyolefins—into more valuable materials,” says Aaron Sadow, director of iCOUP and a scientist in the Division of Chemical and Biological Sciences at Ames National Laboratory, as well as a professor of chemistry at Iowa State University.

Sadow has been a PEPH researcher since the program’s founding at Northwestern in 2019. Other PEPH researchers on the iCOUP leadership team include: Erik Luijten, chair and professor of materials science and applied mathematics at Northwestern; Kenneth R. Poeppelmeier, Charles E. & Emma H. Morrison Professor of Chemistry at Northwestern; and Max ​Delferro, chemist and group leader in the Chemical Sciences and Engineering Division at Argonne National Laboratory and deputy director of iCOUP.

The goal of iCOUP is to create catalysts that transform discarded single-use plastics into more valuable products—a process known as upcycling.

“Plastics—or polymers—are made up of very long, chain-like molecules. Think of each molecule as a string of units that have been concatenated together. If you want to process them, you need to convert these large chains back into smaller segments,” explains Erik Luijten of Northwestern. “The more uniform these segments are in length, the higher quality product you have to work with.”

Currently, these types of products are often made by stitching together (or “polymerizing”) smaller molecules—a process that can be quite expensive. iCOUP researchers are turning this approach on its head.

“Instead of stitching together a bunch of small molecules, we’re breaking down larger molecules in a uniform way and repurposing them,” says Kenneth R. Poeppelmeier of Northwestern. The result is waxes and oils that could then be used to create higher-value products like lubricants and cosmetics. “There should be no reason any plastics should be accumulating anywhere. They’re valuable, highly-engineered resources. Instead of just throwing them out and accumulating as waste, we want to add value back into these materials.”

iCOUP’s objectives rely on cutting-edge team science, striking at the intersection of environmental stewardship and economic efficiency.

“We conducted a preliminary analysis showing the value of converting a plastic bag into a lubricant through upcycling and found four to eight dollars per pound of additional value created. That’s huge,” adds Max Delferro of Argonne National Laboratory. “Of course, it also has the benefit of keeping plastics out of landfills and the environment.”

Although research at iCOUP is focused on basic research rather than commercialization, several of the world’s largest industry players and plastic producers have expressed interest in the group’s innovative approach.

“We’re feeling very optimistic that some of our fundamental scientific advances are going to make their way into new types of applied technology,” says Sadow. “In general, we need to be smarter about how we treat our resources, and plastics are a prime example. They’re designed to make more waste than we need to. We can make much better use of energy, carbon, and natural resources. Our hope is that iCOUP can support a more circular economy and more efficient use of these valuable materials.”

While the group has already published key academic articles on the subject, the EFRC funding will allow them to pursue new methods for breaking carbon-carbon bonds in polymer chains and understanding those methods from physical, chemical, and materials perspectives. In addition to PEPH researchers, the iCOUP team is comprised of members from UC Santa Barbara, University of South Carolina, Cornell University, and University of Illinois, Urbana-Champaign.