Speaker: Shiwang Cheng, Michigan State University
Polymer nanocomposites are important lightweight materials with numerous applications in energy, environment, medication, healthcare, and infrastructure. Their dynamics are among the most important parameters to consider for designing advanced polymer nanocomposites. Compared with large efforts and significant progress on the dynamics of polymer nanocomposites in the linear response region, the understanding of the dynamic properties of polymer nanocomposites at large deformation falls largely behind. Central questions remain to be answered: (i) What are the relevant molecular parameters controlling the dynamics and mechanics of polymer nanocomposites at large deformation? (ii) In which way does the external deformation impact the spatial rearrangement of nanoparticles? This presentation will offer some of our recent work [1-5] with new insights toward answering these fundamental questions. Our focuses are bound polymers and bridging polymers. The microstructure rearrangement of polymer nanocomposites under the influence of external deformation, i.e. uniaxial extension and capillary extrusion, will also be discussed.
 S. Cheng, Dynamics of Polymer Bridges in Polymer Nanocomposites Through a Combination of Dielectric Spectroscopy and Rheology in Dynamics of Composite Materials, edited by A. Schönhals, and P. Szymoniak (Springer International Publishing, Cham, 2022), pp. 63.
 R. Sun, M. Melton, N. Safaie, R. C. Ferrier, S. Cheng, Y. Liu, X. Zuo, and Y. Wang, Phys. Rev. Lett. 126, 117801 (2021).
 J. Yang, M. Melton, R. Sun, W. Yang, and S. Cheng, Macromolecules 53, 302 (2020).
 R. Sun, M. Melton, X. Zuo, and S. Cheng, ACS Macro Letters 9, 1224 (2020).
 L. Song, S. Patil, Y. Song, L. Chen, F. Tian, L. Chen, X. Li, L. Li, and S. Cheng, Macromolecules, DOI: 10.1021/acs.macromol.2c00689 (2022).
Dr. Shiwang Cheng is an Assistant Professor in the Department of Chemical Engineering and Materials Science at Michigan State University. He obtained B.E. (2009) in Macromolecular Science and Engineering at the University of Science and Technology of China, and a Ph.D. (2013) in Polymer Science at the University of Akron. After that, he worked as a postdoc at Oak Ridge National Laboratory between 2014 and 2017 on the dynamics of polymer nanocomposites, focusing on the glassy dynamics at the polymer/nanoparticle interface. Since joining MSU in 2017, Dr. Cheng’s group has mainly worked on the dynamics and mechanics of multicomponent polymeric materials in complex geometries or far from equilibrium for applications in energy, environment, and manufacturing. Dr. Cheng was awarded the Peter Debye Prize for Young Investigator from the International Dielectric Society in 2018, the Ralph E. Powe Junior Faculty Enhancement Awards from Oak Ridge Associated Universities in 2019, and the ACS-PRF Doctoral Young Investigator Grants from the American Chemical Society in 2020.