Research Projects

Permanently crosslinked polymers are widely used in many industries for their excellent mechanical strength, thermal stability, and resistance to deformation. However, these materials are inherently non-recyclable: once the covalent crosslinks are formed, the network structure is fixed, preventing reshaping or reuse without breaking down the entire polymer backbone. This irreversibility creates major challenges for sustainability, waste reduction, and circular use. To overcome these limitations, researchers are developing new polymer networks that combine strong mechanical properties with the ability to rearrange their internal structure under suitable conditions. One promising class is vitrimers, a tunable self-healing polymers that combine mechanical strength and solvent resistance at low temperatures with stress relaxation and recyclability at higher temperatures. This unusual behavior comes from their dynamic associative crosslinks, which undergo addition–elimination reactions that form new bonds before breaking old ones. This keeps the crosslink density constant while letting the network rearrange under stress, allowing full stress relaxation and reshaping without degrading the chains. Unlike conventional thermosets, vitrimers can fully relax stress and be remolded. Their adaptable network structure also helps dissipate shockwaves efficiently, making them attractive for impact-absorbing and self-healing bulk materials and coatings for demanding uses like aerospace components. This balance of durability and recyclability has generated strong interest in understanding how these materials work. While dynamic crosslinks give the network strength and recovery, the chemical difference between the crosslinking groups and the polymer chains often causes microphase separation, forming ordered structures inside the bulk material. This self-organization strongly affects the mechanical and flow behavior. Experiments have shown that such nanostructures can form percolating domains that support both solid-like rigidity and flow under stress. For example, Ricarte and colleagues showed that percolating nanostructures within graft-rich regions create networks that combine strength with reshaping. These findings show that both dynamic crosslinking and microphase separation are key to controlling how chains relax and how the material behaves overall. Although earlier studies have explored dynamic crosslinks in simple systems, the detailed molecular mechanisms behind chain relaxation in microphase-separated, reversible networks remain unclear. Closing this gap is essential for designing new recyclable, self-healing, high-performance polymers with tunable mechanical properties.