Kami Hull & Megan Robertson

WelchX Pilot Grant, Univ. of Texas at Austin & Univ. of Houston

Traditional plastic recycling is inefficient, energy-intensive and environmentally harmful. One approach requires separating the plastic waste by type and reprocessing it at high temperatures to create new products. These recycled plastics have inferior properties, however, limiting their use. Alternatively, recyclers can reduce the plastic waste into its starting materials (monomers), but this takes a great deal of energy and typically uses catalysts that produce toxic waste. Professors Kami Hull and Megan Robertson are seeking to change this.

The two researchers met at the WelchX retreat, quickly bonding over a common passion and compatible skills. Working collaboratively across institutions, Dr. Hull and Dr. Robertson have launched a research project aimed at creating a method to upcycle polystyrene, a widely used plastic that is not biodegradable and recycled in limited quantities, and thus a large contributor to plastic pollution.

Dr. Hull brings expertise in small molecules and organometallic chemistry; Dr. Robertson (who also received a Welch Catalyst for Discovery Program Grant) has polymer chemistry, materials science and sustainability expertise.

The goal of this project is to determine the feasibility of “upcycling” polymers to create higher-value materials with new properties that can lead to practical uses, and to do this in a green, sustainable way. One example is to use reagents such as oxygen and hydrogen peroxide along with transition metal catalysts.

Polystyrene is used in everything from appliances to food storage to packing materials; however, less than 1 percent of it is recycled. Because of its weak benzylic carbon-hydrogen bond, the collaborators hope to develop a method to oxidize polystyrene and modify it to create new polymers and small molecules with industrial utility, potentially converting it to polyolefins, polyesters or mixtures of the two.

“With this one-year WelchX Pilot grant, we hope to demonstrate that it is possible to upcycle polystyrene in a cost-effective, sustainable manner,” Dr. Hull said. “Ultimately, we would hope to partner with plastics manufacturers and recyclers to scale the process for real-world use.”

The team is looking to utilize the differential reactions of 1°, 2° and 3° C–H bonds to promote the selective metal-mediated oxidation and subsequent functionalization of polyolefins without degrading/depolymerizing the polymer backbone.

Dr. Hull’s lab is seeking to develop the proposed functionalization protocols on small molecule model systems and on commercially available polystyrene. Her team is optimizing the reaction conditions and investigating the extent of polymer degradation. Meanwhile, the Robertson group is scaling the polymer functionalization reactions, determining the properties of the polymers, and optimizing the protocol for copolymer properties. In addition, her lab plans to optimize the developed reaction protocols on polystyrene from recycled streams.

The two teams are coordinating in virtual biweekly meetings, in-person sessions, and student exchanges through which students can visit the other laboratory.

“The WelchX retreat provides the perfect opportunity to meet colleagues from across the state who have related, yet distinct, research interests,” said Dr. Robertson. “It truly is an incubator for new collaborations in Texas. With this opportunity, our research groups hope to make a real difference in plastic sustainability for society.”