Tsai-Wei Lin, University of Illinois at Urbana-Champaign
Yun-Ju Chen, University of Illinois Urbana-Champaign
Min-Hsien Lin, University of Illinois Urbana-Champaign
Dynamic bonds, which can break and reform or undergo exchange, have long been a key motif in polymer science. Their role in controlling the mechanical properties of polymer networks has been historically important in the context of rubber, and as a route to tune or control the viscoelastic properties in both melt networks and swollen gels. There has recently been a dramatic increase in chemistries – and consequently applications – available to polymer scientists as they realize the possibilities of this class of materials. These advances have benefited from progress in polymer physics, where molecular-level physical insights can guide molecular-level design of dynamic networks.
This talk will highlight examples from our recent research where computational and theoretical polymer physics is used to understand both dynamic and thermodynamic phenomena in dynamic networks, in close collaboration with several experimental and theoretical colleagues. We show how the kinetic and mechanistic attributes of dynamic bonds can be engineered to control material dynamics. In the glassy state, we show how activated segmental motions couple to molecular bond exchange events. In the rubbery state, we can predict how competition between bond exchange mechanisms can be used to engineer stimuli-responsive molecular rearrangements. Finally, we predict how bond exchange motifs can be harnessed to affect equilibrium properties, and can be used to promote polymer miscibility. These examples highlight not only the promise of this important class of materials, but the abundance of scientific questions that remain to be addressed in our understanding of these fascinating systems.
