Injectable Poly(oligoethylene glycol methacrylate)-Based Hydrogels Fabricated from Highly Branched Precursor Polymers: Controlling Gel Properties by Precursor Polymer Morphology

The physicochemical properties of injectable hydrogels are typically modified by altering the chemistry of the precursor polymer and/or the amount or type of cross-linker, both of which can lead to hydrogels with altered mechanics, swelling, degradation, and other key physical properties. Herein, we describe an alternative approach to tune the properties of injectable hydrogels (here, based on hydrazone cross-linked poly(oligoethylene glycol methacrylate), or POEGMA) by altering the architecture of the precursor polymers through branching. Hydrogels prepared using highly branched precursor polymers had nearly identical chemical compositions but exhibited markedly different physical properties relative to linear precursor hydrogels on which we have previously reported. Specifically, increasing the degree of branching resulted in increased degradation time and stiffness but decreased gelation time and gel swelling. The mechanical properties of highly branched hydrogels are relatively insensitive to the mass...