Integration of hydrogels with functional nanoparticles using hydrophobic comb-like polymers as an adhesive layer

Surface functionalization of hydrogels is a strategy that can partly endow hydrogels with desired properties while keeping the intrinsic hydrophilicity and biocompatibility of the hydrogel network intact. Herein, we report a ubiquitous strategy to functionalize the surfaces of hydrogels with functional nanoparticles. By taking advantage of quaternization reactions confined to hydrogel/oil immiscible interfaces, comb-like polymers are covalently bonded to the surfaces of hydrogels. The comb-like polymers on the hydrogel surface form a modified hydrophobic layer, which can further act as an adhesive layer and contribute to the integration of hydrogels with functional nanoparticles. For example, the integration of hydrogels with superhydrophobic silica nanoparticles endows the hydrogels with controllable surface wettability and water adhesion. Meanwhile, a hydrogel-based supercapacitor is also prepared via integration of hydrogels with conductive polyaniline nanoparticles. Moreover, the universality of the current approach to different hydrogel systems is confirmed. Consequently, it is expected that this study can provide a general strategy for the fabrication of multifunctional hydrogels.