text: Because of the non-covalent host-guest interaction, the polymer backbone can have enough flexibility to diffuse. If a crack exists in the materials, after compressing the two materials around the crack, because of the fast exchange of the host-guest molecular structure, the crack will rejoin again revealing good self-healing properties. Harada et al reported a self-healing hydrogel constructed by vinyl-group-modified cyclodextrin and adamantane. Another strategy is to use the interaction between the polymer backbone and host molecule (host molecule threading onto the polymer). If the threading process is fast enough, self-healing can also be achieved.