The macroscopic properties of polymers emerge from a combination of molecular (covalent and noncovalent associations, van der Waals forces) and macromolecular (entanglement, reptation) interactions. Light uniquely offers precise, tunable, and external spatiotemporal control over molecular interactions, which can be translated into macroscopic responses. Photochemical crosslinking and cleavage allow precise tailoring of the structure of elastic polymer networks. Recently, researchers have developed strategies to tune the temporal properties of viscoelastic networks that rely on changes in the composition and structure of the crosslinks, accessing multiple timescales for stress relaxation. I will describe my group’s design of photoswitchable dynamic covalent crosslinks that enable external, spatiotemporal, and reversible control of viscoelasticity in hydrogels and vitrimers. I will discuss our efforts to elucidate the molecular mechanism underlying these macroscopic changes, as well as rational optimization of the structures to enable applications in 3D cell cultures and recyclable elastomers.

Reactivity-property relationships in photocontrolled polymer networks

256th National Meeting (2018)

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