Responsive Polypseudorotaxane Hydrogels Triggered by a Compatible Stimulus of CO2

Realizing the reversible transformation of the supramolecular hydrogels is essential for their application as smart materials. The reversible sol-gel transition of the polypseudorotaxane (PPR) hydrogels is achieved through adding a CO 2 -switchable guest molecule into the PPR hydrogel of poly(ethylene glycol) (PEG) and α-cyclodextrins (α-CDs). Alternating treatments with CO 2 and heating drive such reversible transition due to the competitive complexation as evidenced by 2D NOESY 1 H NMR and isothermal titration calorimetry as well as X-ray diffraction. The present work describes a straightforward way to obtain switchable PPR hydrogels triggered by a compatible stimulus of CO 2 . These stimuli-responsive PPR hydrogels have potential applications as biomaterials.