MS&E Faculty Search Presentation: Dr. Shu Wang

UW-Madison Department of Materials Science and Engineering welcomes Dr. Shu Wang. Their presentation on “Bridging Molecular Mechanochemistry and Network Fracture Mechanics” will be on Monday, Jan. 27 in MS&E 265 from 4 p.m. to 5 p.m.

Abstract

Polymer networks, spanning applications from automobile tires to hydrogels, are ubiquitous in daily life and are designed to endure significant loads and deformations. However, repeated stresses over time can lead to crack formation, potentially resulting in catastrophic failure under substantial loads and ultimately limiting their lifespan. Understanding the mechanisms that govern fracture in polymer networks is therefore critical for improving their durability. While fracture is often perceived as a macroscopic mechanical problem, the advancement of a crack in a polymer network requires breaking polymer chains and chemical bonds—a process intrinsically tied to their chemistry. The extent to which the molecular details of covalent polymer networks dictate their macroscopic mechanical properties remains an open question. In this talk, I will begin with a brief historical perspective on the fracture of polymer networks and introduce a molecular view that ties network fracture to polymer chain scission, supported by experimental evidence. I will then present a semi-quantitative model linking chain scission reactivity and network topology to intrinsic fracture energy. Beyond polymer chains, I will highlight the critical role of crosslinker chemistry, demonstrating how the same mechanochemical reactions can either weaken or strengthen the network depending on their placement. These findings provide a framework for designing covalent polymer networks with tailored mechanical properties.

Bio

Shu received his Ph.D. in Chemistry from Duke University in 2022 under the guidance of Prof. Stephen L. Craig and Prof. Michael Rubinstein. During his graduate studies, Shu developed a keen interest in rupturing large molecules—not merely for the fun of it, although he found it immensely satisfying, but to understand how the scission of chemical bonds impacts the tear resistance of the polymeric materials they compose. Building on his growing expertise in polymer chemistry and physics, Shu is currently exploring polymer mechanics as a postdoctoral associate with Prof. Xuanhe Zhao at the Massachusetts Institute of Technology. His research accomplishments have been recognized with several awards, including the Henkel Award, the Shaffer Hunnicutt Fellowship, and the Charles Bradsher Fellowship from Duke University.