About the Speaker:

Junpeng was born and raised in a small town near Xi’an, China, where the Terracotta Army is located. He obtained his B.S. at the University of Science and Technology of China in 2010. After that, he went to Duke University to work on polymer mechanochemistry with Steve Craig and obtained his Ph.D. degree in chemistry in 2015. In his Ph.D. studies, Junpeng has designed and synthesized a series of stress-responsive polymers; more importantly, he has quantified the force-induced reactivity and elucidated the mechanisms by applying the technique of single-molecule force spectroscopy to the systems. In 2016, after his Ph.D. studies, he worked as a postdoc with Luping Yu at the University of Chicago, where he designed and synthesized a series of porous conjugated polymers and assembled them as cathode materials for lithium ion batteries. In early 2017, he moved to MIT and worked for Jeremiah Johnson as a postdoc. In the Johnson group, Junpeng has developed a method that allows for the quantification of different orders of cyclic defects in polymer networks, and the method enables the accurate prediction of polymer network elasticity. In January 2019, Junpeng started his independent career in the Department of Polymer Science at the University of Akron.

About the Seminar:

Title:

Olefin Metathesis–Based Chemically Recyclable Polymers: From Monomer Design to Material Properties

Abstract: 

Synthetic polymers such as plastics, nylon, and synthetic rubber have been used in nearly every aspect of modern life; the dominant use of these polymeric materials is driven by their durability and versatile thermomechanical properties. However, the excellent thermal and chemical stability of commercial polymers makes them challenging to recycle and reuse. Currently, over 300 million tons of plastics are produced each year and 95% of them are not recycled. Consequently, most polymer products are consigned to landfills or thrown into the ocean, causing serious environmental concerns. Moreover, the production of polymers consumes finite fossil resources such as petroleum and coals, and
the inability to recycle these materials causes concerns regarding the sustainability of their use. Sustainable polymers have received considerable attention as an option for sustainable materials. Despite the developments, few chemically recyclable polymers can match the stability and mechanical properties of the polymeric materials in current use. This presentation will showcase our recent effort in overcoming these challenges. We developed a new class of depolymerizable polymers from fused-ring cyclooctenes; the fused-ring system lowers the ring strain energies of the monomers and allows the corresponding polymers to depolymerize into the monomers. Importantly, the polymers show excellent
thermal stability, and their thermomechanical properties can be tuned—by varying the functional group on the fused ring—to access the properties of both rubber and plastics.