Hydrolysis and Oxidation in Vitrimers: Linking Chemical Degradation to Constitutive Behavior and Recyclability

Epoxy thermosets are widely used in engineering applications due to their superior adhesive strength, structural integrity, and chemical resistance. However, their permanently crosslinked molecular structure prevents reshaping or recycling after use, creating significant sustainability challenges. The emergence of covalently adaptable thermosets, known as vitrimers, offers a promising pathway toward recyclable thermoset materials. Yet, the same dynamic bond exchange mechanisms that enable vitrimer reprocessability also make them susceptible to long-term degradation in harsh environments. Prolonged exposure to elevated temperatures, oxygen, and moisture can alter their chemical structure and compromise mechanical performance. Despite their promise for applications in aerospace, naval systems, and other demanding environments, a fundamental understanding of how environmental aging affects vitrimer durability and recyclability is lacking. The objective of this project is to establish a comprehensive framework to elucidate how aging processes influence the mechanical integrity, bond exchange dynamics, and long-term reliability of vitrimers, enabling their sustainable deployment in high-performance applications. The project integrates experimental characterization, theoretical modeling, and computational simulations to investigate the coupled effects of hydrolytic and thermo-oxidative aging on vitrimer behavior. Systematic experiments across multiple length scales will quantify the evolution of mechanical properties under controlled environmental exposures, establishing direct links between degradation mechanisms and macroscopic performance. Concurrently, a diffusion–reaction framework will be developed and coupled with a transient network theory-based constitutive model to capture the interplay between irreversible chemical degradation and dynamic bond exchange reactions. These efforts aim to uncover the mechanistic pathways governing vitrimer aging and to provide predictive capability for long-term material performance in extreme service conditions. The outcomes will include design guidelines for enhancing durability, maintaining recyclability, and optimizing performance under environmental stressors. Educational activities will involve training graduate and undergraduate students in polymer mechanics, chemistry, and materials science through research activities in the PI’s laboratory. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2554138 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Trisha Sain | Institution: Michigan Technological University, HOUGHTON, MI | Award Amount: $462,358 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2554138 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2554138.html