Brush Polymers as Nanoscale Building Blocks for Hydrogel Synthesis
Fei Jia, Jake Song, Joshua M. Kubiak, Michika Onoda, Peter J. Santos, Koki Sano, Niels Holten‐Andersen, Ke Zhang, Robert J. Macfarlane
Abstract
High branch functionality (f) materials have garnersed significant attention as building blocks for hydrogels as their ability to form abundant network connections yields mechanically robust gels that can potentially tolerate the negative effects of topological defects. Herein, we report the synthesis of hydrogels using brush polymers and investigate the influence of both f and polymer topology on the mechanical properties of resulting hydrogels. Our study suggests that both the high f and the extended conformation of polymer brushes that are attributed to the nanoscale shape of the brush polymers enable them to exhibit elevated gel stiffness and can effectively minimize the effects of topological defects, induce gelation at much lower cross-link concentrations, and display restrained swelling compared with gels made with more flexible polymers. In addition, because the brush polymers adopt discrete nanoparticle-like morphologies in solution, tailoring the location of the cross-linking groups at different points along the brush surface allows for different topological connectivities (e.g., side-to-side and end-to-end) to be generated, further controlling the resulting mechanical properties of the cross-linked networks. Brush polymers are therefore promising building blocks for hydrogels with highly tunable mechanical and physical properties and for the investigation of structure–property relationships affected by the gel network topology.