Polymer hydrogels are an important class of material that holds great potential in biological and biomedical applications, due to their highly tunable mechanical properties and the structural similarities between hydrated polymer networks and the extracellular matrix. However, although many different crosslinking strategies have been developed to synthesize polymer hydrogels, it is still currently difficult to eliminate topological defects that negatively affect gel mechanical properties. Additionally, because linear polymers of sufficient length to generate robust hydrogels are inherently prone to chain entanglement, it can be difficult to fully isolate the effects of physical and chemical crosslinking on gel mechanical behavior. In this study, we introduce a unique structure of polymer hydrogel which aims to reduce both structural defects and intermolecular entanglements via the use of bottlebrush polymers (BBPs). These hydrogels demonstrate that the densely packed side chains on BBPs can both significantly minimize chain entanglement, as well as reduce the effects of topological defects on properties like gel modulus or swelling ratio. Compared with conventional linear or star polymer hydrogels, BBPs gels show much lower gelation point. In addition, with proper synthetic design, the effective crosslinking is able to significantly reduce small molecule diffusion through the gel, as well as maintain relatively robust polymer network structure upon swelling. The combination of these unique properties makes these BBP gels ideal for future biological or biomedical applications.

Hydrogels from crosslinked bottlebrush polymers

2019 Fall National Meeting

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