Dadmun Group Explores the Future of Plastic Recycling with Polymer Chemistry
Professor Mark Dadmun and his research group recently published papers in both ChemSusChem and Nature Communications. These papers describe the group’s ongoing efforts to tackle more efficient plastic recycling through polymer chemistry.
Plastics, which are made of polymers, have been increasingly woven into modern life since the 1950’s. Single-use plastics originally gained popularity with consumers through a combination of convenience and affordability. However, the durability of plastics, a key feature that contributed to their success, has led to concerns over their persistence in the waste stream.
Since the 1980’s, plastic recycling has been explored as a possible solution. Unfortunately, early recycling methods were ineffective with plastics, and modern recycling rates remain low at only around 9% globally.
Plastic recycling has been a long-term area of research for Dadmun, whose lab broadly focuses on investigating how the specific molecular structures of a polymer impact its properties. Understanding how to control these structures is critical to effectively recycling polymer materials, but when Dadmun sought to apply his earlier work to recycling, he was met with roadblocks.
“In the early 2000’s, the general sentiment was that we were never going to recycle polymers,” said Dadmun. “It’s only been in the last 10 years that perspectives have changed and the idea that we can and will develop new materials or new processes for plastics recycling has been supported.”
Dadmun’s group has used this shift to apply their research to the problems of modern chemical recycling. Chemical recycling directly manipulates the molecular structure of plastic polymers, breaking them down into their component parts and allowing them to be used to create new materials.
“Polymers are long-chain molecules, hundreds to thousands of individual units bonded together, and it’s that really big structure that gives them many of their properties,” said Dadmun. “Unzipping that long chain of molecules is straightforward but expensive, and this is the problem polymer scientists have been trying to solve.”
One approach is to break down all the individual units of the polymer and try to link them back together. However, this method can be inefficient as it requires the breaking and reforming of thousands of chemical bonds. Dadmun’s recent work investigates the possibility of breaking polymers down into larger groupings of units to be repolymerized, a process that should be more time and energy efficient.
The first of Dadmun’s recent publications focuses on understanding how a polymer breaks down into individual units. Shelby Watson-Sanders, a recent PhD graduate and member of Dadmun’s research group, co-authored the publication that describes this work.
“My interest in plastic waste initially sparked from a paper that addressed the release of estrogen chemicals from plastic when heated in the microwave. This revelation made me aware that plastic is ubiquitous and could pose health risks,” said Watson-Sanders. “In this work, we observed that our consumer waste plastic flakes broke apart into a powder and remained undissolved in solution until later in the reaction.”
Watson-Sanders went on to discover that some parts of the plastic broke down more easily, while others remained intact. These results suggested a possible explanation for the creation of micro and nanoplastics and led to the development of the second paper, published in Nature Communications. Watson-Sanders noted that the results of this work and the subsequent second publication prompted her to evolve her dissertation into an exploration of recycling plastic waste and the potential consequences of neglecting consumer waste.
In addition to Watson-Sanders, the team working on this research included undergraduate student Kendra Day. At this year’s Department of Chemistry Undergraduate Research Symposium, Day described this research in her award-winning presentation. She graduated this spring and will begin graduate studies at Cornell University in the fall. In the future, Dadmun and his team hope this ongoing work will contribute to more effective methods for polymer recycling. This could, in turn, contribute to increased plastic recycling and decreased plastic waste in the environment, as well as the development of new materials.