(598c) Transient Stimulation of Hydrogel Environments for Non-Equilibrium Mechanical Control | AIChE

(598c) Transient Stimulation of Hydrogel Environments for Non-Equilibrium Mechanical Control


FitzSimons, T. - Presenter, University of Texas At Austin
Rosales, A., University of Texas At Austin
Betancourt, T., Texas State University
Thapa, K., Texas State University
Synthetic hydrogels offer an intriguing platform for biomaterial applications due to their wide chemical library and top-down design. One of the most important considerations for these systems is the crosslinking chemistry. Recent research has highlighted the utility of dynamic crosslinking, such as guest-host interactions, ionic bonding, and reversible covalent chemistries. Our lab specializes in the incorporation of reversible covalent chemistries into hydrogel networks in order to control the viscoelastic properties for a variety of applications. In this research, we show that transient stimulation of a reversibly crosslinked hydrogel can control the resulting hydrogel mechanics in a reversible way, whether that be through nanoparticle controlled temperature spikes or chemical-fuel induced sequestering. The starting hydrogel in this system relies on an inert poly(ethylene-glycol) (PEG) star polymer functionalized with either conjugate acceptors or thiols. These crosslink through a reversible thia-conjugate addition mechanism. Our work demonstrates how temperature can effectively control the crosslinking reaction, and the incorporation of photothermal nanoparticles allows near-IR light to be the temperature change trigger. Additionally, the conjugate acceptors naturally hydrolyze in the native aqueous hydrogel environment. Through a combination of hydrolytically labile orthogonal chemistries, the concentration of conjugate acceptor can be controlled in a transient fashion. This setup allows a mechanical change in the hydrogel in the presence of a reactive fueling molecule that spontaneously reverts to the original state when that reactive fuel is consumed. Our research demonstrates how transient non-equilibrium systems can be an effective way to stimulate hydrogel mechanical changes that naturally revert back to the originally state.