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We developed a mechano-responsive hydrogel that is driven by the dissociation of a host–guest complex. The hydrogel comprised a thermoresponsive linear polymer with adamantane as a guest molecule in its side chain and a nonthermoresponsive network structure with β-cyclodextrin as a host molecule. Immobilization of the thermoresponsive polymer in the hydrogel via host–guest interaction resulted in a partial restriction of its phase transition, even above its lower critical solution temperature (LCST). The hydrogel demonstrated a decrease in transmittance when mechanical stress was applied at a temperature above its LCST, indicating that the phase transition of the thermoresponsive polymer was induced by the dissociation of the host–guest complex under mechanical stress. Moreover, this mechano-responsive behavior was repeatable by cooling the hydrogel to redissolve the thermoresponsive polymer. The strategy of the mechano-responsive phase transition will be useful for various applications that demand the control of desired functions by applied stress.

Chitosan (CS), an amino-polysaccharide, has applications in various areas such as drug delivery, biotechnology, food technology, and numerous industrial applications. Monoliths have been developed continuously for several decades, and today, they hold an impressively strong position in highly efficient separation, ion exchange, catalysis, and chromatography. In our previous study, a hierarchical chitin (CT) monolith was fabricated using chemically modified CT through the thermally induced phase separation (TIPS) method. This report generated a template-free approach to prepare highly effective, stable, and reusable hierarchically porous CS monoliths by deacetylation of CT monoliths. The acquired CS monoliths exhibited a high surface area at 144.1 m 2 g −1 owing to the presence of hierarchical macro-and mesopores. The monoliths demonstrated efficient removal of metal ions from an aqueous solution in a flow system (adsorption capacity at 92.1 mg g −1 ). To gain durability of CS monoliths in acidic and basic environments, epichlorohydrin (ECH) was used as a cross-linking agent. The cross-linked monoliths also exhibited excellent performance in the adsorption of Cu(II) ions from the solution (64.4 mg g −1 ) and good reusability in multiple adsorption−desorption cycles without losing significant performance (with 90.7 ± 6.1% adsorption efficiency and 88.5 ± 7.2% desorption efficiency). The fabricated CS monolith can be modified and applied to various fields such as protein separation, catalysis, and drug delivery.

Thermoresponsive poly(N-isopropylacrylamide) hydrogels reinforced with supramolecular cellulose fibers were fabricated. Adamantane was immobilized on the surface of the cellulose fibers, and β-cyclodextrin was introduced into the hydrogel matrix. The interfacial host–guest interaction between the filler and the matrix effectively enhanced the mechanical strength of the hydrogels both in the swelling and deswelling states.