A double supramolecular crosslinked polymer gel exhibiting macroscale expansion and contraction behavior and multistimuli responsiveness

Supramolecular crosslinked polymer gels show special properties largely as a result of the combined mechanical properties contributed by the covalently linked polymer chains and the reversible, stimuli-responsive supramolecular crosslinks. Most supramolecular crosslinked polymer gels contain only one kind of physical cross-link. Herein we report a novel supramolecular polymer gel containing two types of physical crosslinks based on two kinds of non-covalent interactions that are orthogonal: DAN·DeUG quadruply hydrogen-bonding interactions and benzo-21-crown-7/dialkylammonium salt host-guest interactions. One of the crosslinked networks is used to maintain the gel state while the other modulates the crosslink density through external stimuli, thereby causing a volume change of the gel. This double supramolecular crosslinked polymer gel shows macroscale expansion and contraction behavior and multistimuli responsiveness. Therefore, we successfully demonstrate that the macroscopic property change of supramolecular systems can be induced by controlled self-assembly on a molecular scale.