State transition of macroscopic supramolecular hydrogel by the host-guest coverage effect

In this work, a hydrophobic guest monomer containing adamant end-group was synthesized and introduced into the acrylamide hydrogel system to prepare macroscopic guest hydrogel. The swelling, transparency, and mechanical properties of the guest hydrogels can be significantly changed by soaking the guest hydrogel into hydrophilic cyclodextrin solution because the hydrophobic guest groups were recognized and covered by the hydrophilic host molecules. In addition, the surface lubrication property could be adjusted by changing the proportion of acrylamide and adamantane monomers in the hydrogel system. More importantly, cyclodextrin can bind with adamantane through host-guest interactions, enabling the adjustment of the hydrophilicity/hydrophobicity properties of the hydrogel system. By controlling the assembly time, the hydrogel with different lubrication behaviors can be obtained. The controllable surface friction that this specific binding of host-guest interaction has broad application prospects in intelligent device, bionic lubrication and other fields.