03/24/2026
By Dongming Xie
Chemical Engineering Seminar - Rheology with Impact: Hydrogen-Bonded Sheets Strike Back
Prof. Steve Lustig, Department of Chemical Engineering, Northeastern University
Day: Thursday, March 26, 2026
Time: 3:30-4:45 p.m.
Location: Shah Hall 303
Abstract:
The design of next-generation protective materials demands a deep understanding of nanoscale structural dynamics under extreme, multi-axial deformations. Using multichannel AM-FM atomic force microscopy, we have characterized the nanostructure of Kevlar® KM2® Plus fibers subjected to controlled rheometric deformations and high-rate ballistic impacts. Spatially resolved measurements quantify key features – including fibril widths, void dimensions, crystal misorientation angles, and pleat lengths – revealing independent contributions from both tensile and transverse compressive strains to fibrillar response. These findings, supported by statistical mechanics analyses of morphological distributions, challenge conventional focus on axial tensile properties alone and highlight the critical role of transverse compression and associated heat dissipation mechanisms in enhancing ballistic resilience. Such insights underscore the need for materials that synergistically optimize tensile strength, compressive toughness, and thermal management at the nanoscale.
Building on these principles, we introduce graphamid – a groundbreaking two-dimensional (2D) polyaramid polymer that extends the paradigm from 1D chain architectures to covalently linked molecular sheets. A homopolymer composed of hexafunctional benzene nodes interconnected via amide linkages, graphamid forms extended covalent organic frameworks with dense intermolecular hydrogen-bonding networks, enabling exceptional mechanical performance, high temperature stability, and out-of-plane transport properties far surpassing traditional aramids like Kevlar®. Synthesized uniquely in our laboratory from the novel monomer 2,4,6-triaminobenzene-1,3,5-tricarbaldehyde (TABTCA) via reversible acid-catalyzed polycondensation to graphimine followed by oxidation, graphamid represents the first realization of highly compacted, imine- and amide-linked 2D polymers under ambient conditions. These advances open transformative pathways for lightweight, ultra-strong, heat-resistant films and composites in high-performance protective applications.
Biography:
Steve Lustig joined the Department of Chemical Engineering at Northeastern University as an associate professor in September 2016. Before moving to Boston, he was an adjunct professor at the University of Delaware in the Department of Chemical and Biomolecular Engineering and the Department of Materials Science and Engineering, where he taught statistical thermodynamics, polymer physics and green engineering for 8 years. He was a principal investigator at the DuPont Central Research & Development laboratories at Experimental Station in Wilmington, Delaware for 26 years. In 2013 he was awarded the AIChE Industrial Research & Development Institute Award for his work at DuPont. He is a Fellow of the Royal Society for Chemistry and was elected to the National Academy of Inventors in 2025.