Self-Healing, Expansion-Contraction, and Shape-Memory Properties of a Preorganized Supramolecular Hydrogel through Host-Guest Interactions

Supramolecular materials cross‐linked between polymer chains by noncovalent bonds have the potential to provide dynamic functions that are not produced by covalently cross‐linked polymeric materials. We focused on the formation of supramolecular polymeric materials through host–guest interactions: a powerful method for the creation of nonconventional materials. We employed two different kinds of host–guest inclusion complexes of β‐cyclodextrin (βCD) with adamantane (Ad) and ferrocene (Fc) to bind polymers together to form a supramolecular hydrogel (βCD‐Ad‐Fc gel). The βCD‐Ad‐Fc gel showed self‐healing ability when damaged and responded to redox stimuli by expansion or contraction. Moreover, the βCD‐Ad‐Fc gel showed a redox‐responsive shape‐morphing effect. We thus succeeded in deriving three functions from the introduction of two kinds of functional units into a supramolecular material. Nonconventional intelligence: Multifunctional supramolecular materials are expected to be the next generation of intelligent soft materials. Supramolecular polymeric materials were created through host–guest interactions (instead of conventional covalent cross‐linking) to form two different kinds of host–guest inclusion complexes. The resulting gels displayed the properties of self‐healing, expansion–contraction, and shape memory (see picture).