Supramolecular Reinforcement of Polymer–Nanoparticle Hydrogels for Modular Materials Design

Moldable hydrogels are increasingly used as injectable or extrudable materials in biomedical and industrial applications owing to their ability to flow under applied stress (shear‐thin) and reform a stable network (self‐heal). Nanoscale components can be added to dynamic polymer networks to modify their mechanical properties and broaden the scope of applications. Viscoelastic polymer–nanoparticle (PNP) hydrogels comprise a versatile and tunable class of dynamic nanocomposite materials that form via reversible interactions between polymer chains and nanoparticles. However, PNP hydrogel formation is restricted to specific interactions between select polymers and nanoparticles, resulting in a limited range of mechanical properties and constraining their utility. Here, a facile strategy to reinforce PNP hydrogels through the simple addition of α‐cyclodextrin (αCD) to the formulation is introduced. The formation of polypseudorotoxanes between αCD and the hydrogel components resulted in a drastic enhancement of the mechanical properties. Furthermore, supramolecular reinforcement of CD–PNP hydrogels enabled decoupling of the mechanical properties and material functionality. This allows for modular exchange of structural components from a library of functional polymers and nanoparticles. αCD supramolecular binding motifs are leveraged to form CD–PNP hydrogels with biopolymers for high‐fidelity 3D (bio)printing and drug delivery as well as with inorganic NPs to engineer magnetic or conductive materials. Cyclodextrin‐based supramolecular binding enhances the viscoelastic properties of polymer–nanoparticle hydrogels and provides modular exchange of building blocks. This paradigm expands the interactions available for the formation of this class of injectable nanocomposite hydrogels, enabling unique applications in 3D printing, magnetic materials, and conductive hydrogels.