By: Yuhao Chen

Hi! My name is Yuhao Chen and I am a Chemistry graduate student in Dr. Travis Williams’ group at the University of Southern California. As a group famous for catalysis studies, we focus on not only exploring robust catalytic systems for upgrading ‘dirty environmental waste’ into ‘valuable products’ in the laboratory bench, but also transferring our science into the industrial scale. For me personally, I am discovering a new catalytic condition to aid the fight against plastic waste and reclaim value from those post-consumer products.

Polyolefin waste, a typical type of plastic waste, has become an increasing and omnipresent concern for our society, since polyolefin is so widely used in our daily lives in items such as water bottles, packaging and vehicle manufacturing. Based on reports from the EPA, there is more than 18 million tons of polyolefin waste not getting recycled each year! Unfortunately, due to the particular inertness of polyolefin, we are really short of any sustainable recycling method for this material, leading to disposal by landfilling, oceanic dumping and burning which result in irreversible environmental issues.  Some new solutions have come out in recent years, such as costly UV radiation and concentrated acid treatments, but the enormous safety and efficiency concerns dramatically limit their applications.

Therefore, this led to me to wonder whether it is possible to determine a mild and inexpensive catalytic system to convert polymer waste into desirable ‘chemical feedstock’ compounds. In order to discover a promising catalytic system, we need to get full understanding of the molecular structure of the polyolefin polymer to determine what makes it so unreactive. This is where our chemists start to develop new catalytic systems with proper mechanisms. After a series of screening experiments, along with kinetic monitoring data, we started to realize the barriers that led to so many failed previous attempts in the past few years! With these valuable determinations, we began to build our catalytic system based on transition metals, a group of promising candidates in the world of catalysis. We are now actively investigating the interactions between metal catalysts and other components in the system, which we consider the best clues to improve our system and overcome the reaction barriers.

The clean ‘chemical feedstock’ samples we can recover from the dirty environmental waste .

So far, I have gotten some fairly impressive results in the past spring – this vigorous plastic polymer was observed to be depolymerized using our mild catalytic system, with very decent efficiency. Over this summer, I aim to further develop our catalytic system with an interdisciplinary perspective – combining organic chemistry with more computational strategies to analyze to the detailed role of each catalytic component in our system and optimize the reaction product selectivity.

I feel very thankful for receiving the Wrigley Institute’s Norma and Jerol Sonosky Summer Fellowship for this year, enabling me to continue my research over this summer. I am really proud of being involved in such meaning research, as our group is getting closer to solve a tough environmental problem which has been challenging our society over the past 30 years!