In recent years, much attention has been directed toward supramolecular chemistry. Although there have been a number of reports on supramolecular complexes and polymers, there are much less on supramolecular materials. More recently, we have found that supramolecular materials formed by host-guest interactions show unique properties, such as highly tough, flexible, and self-healing properties1. When β-cyclodextrin(CD) monomer and guest monomer containing adamantane were copolymerized with acrylamide, we obtained a self-healable gel, because the gel is formed by host-guest interactions2. We have also obtained a highly flexible gel by controlling a host-guest ratio. Recently, we found that [c2]daisy chains (doubly threaded host-guest dimers) can be used for stimuli-responsive materials3. When daisy chains composed by azobenzene as a guest and α-CD as a host are incorporated in the polymer network with tetra-armed polyethylene glycol, the network polymers show photo-responsive properties. When the gel was irradiated by UV light, the gel contracted, but when the contracted gel was irradiated by visible light, the gel stretched again to give an original state. Moreover, we found that freeze-dried gel (xero-gel) stretched 10,800 times faster than in water. Host-guest parts are incorporated in the gel only by mechanical bonds. Therefore, the system is the first example of artificial muscle moved through sliding between molecules, like sarcomere composed by actin and myosin filaments.

Supramolecular materials: Self-healing and stimuli-responsive polymeric materials through host-guest interactions

253rd National Meeting (2017)

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