To realize adhesion between hard materials, we have focused
on semihard materials based on polyacrylamide xerogel
possessing host and guest molecules due to two reasons.
First, xerogels will show the adhesion through the host−guest
interaction by the addition of small amounts of water on the
surface because the flexibility and the molecular mobility of the
xerogel surface restore under the wet condition. Second,
xerogels (tensile strength ∼12 MPa) are much harder than
hydrogels (∼6.3 kPa). Once xerogels adhere each other
through the host−guest interaction, the strong adhesion
strength that hydrogel cannot perform will be formed after
drying. Herein we demonstrate the strong adhesion strength
between the interfaces of xerogels via host−guest interactions.
Furthermore, we create self-healing semihard xerogels that
recover to material strengths close to the initial strength
through supramolecular cross-linking.