Date(s) - 02/01/2022
3:00 pm - 4:00 pm
Dr. Chase Thompson
NRC Postdoctoral Fellow, Polymers and Complex Fluids Group
National Institute of Standards and Technology
Dr. Chase Thompson received his B.S. in Polymer Science from the University of Southern Mississippi in 2015. In the same year, he began working on his doctorate under the guidance of Dr. LaShanda Korley at Case Western Reserve University in the Macromolecular Science and Engineering department where he focused on the confinement and control of supramolecular polymers in networks and composites. Following a move to the University of Delaware, Chase completed his Ph.D. in Materials Science and Engineering in the summer of 2020. He is currently a National Research Council (NRC) Postdoctoral Fellow at the National Institute of Standards and Technology (NIST) where he works in the Polymers and Complex Fluids Group under the guidance of Dr. Sara Orski. Chase’s primary focus at NIST is the design, synthesis, and characterization of model polyolefins to deconvolute the complex structure-property relationships in these commodity thermoplastics, especially where these efforts could assist in the identification, separation, and compatibilization of post-consumer plastic waste.
A material’s structure defines its assembly, morphology, and characteristics in the bulk; understanding this intricate relationship between chemical composition and material properties is vital to the development and application of functional materials. In this talk, I first discuss our efforts to explore the structure-property relationships in synthetic supramolecular polymer systems that are inspired by natural materials. A focus on how minute changes in system chemistry can be used as a convenient pathway for tuning the assembly patterns of the non-covalent interactions is highlighted. Interpenetrating networks (IPNs) and nanocomposites are both discussed as routes for controlling the dynamic character of the final material by providing handles for shifting their morphology and supramolecular associations. Changes in the materials’ chemistry are observed to understand how interactions between chemical motifs define the micro- and macroscopic properties of the system. These changes in material composition are highlighted as tools for shifting the stimuli-responsive behavior of the polymer films.
In the latter half of the talk, I discuss efforts towards applying these same structure-property concepts toward the design, synthesis, and characterization of model polyolefins Polyolefins are one of the most important classes of thermoplastic polymers in the 21st century yet decoding the structure of industrially-produced polyolefins remains a challenge due to their high crystallinity and the presence of branches along the polymer backbone. These issues are further compounded by the distribution of branches that shift the poly(ethylene) architecture (e.g. gradient, blocky). To address these challenges in characterizing structurally complex polyolefins we have devised a method for the synthesis of regioregular linear low-density poly(ethylene) (LLDPE) models through ROMP that produces polyolefin block copolymers and homopolymers with precise branch spacing at every 8th carbon. The synthetic challenges and intensive characterization of these block copolymers—both their unsaturated and saturated derivatives—are described, especially regarding how changes in branch composition affect dilute solution properties as measured using high temperature-gel permeation chromatography (HT-GPC). These materials have important applications in improving the separation of mixed polyolefin streams to better understand how different branching behavior dictates their bulk polymer properties.