Abstract: A novel method to prepare polyrotaxane in solution by α-cyclodextrins and dumbbell-like poly(ethylene glycol) derivative with reversible acylhydrazone bond and big end stopper (2’,4- dinitrophenyl) is described. Stimulated by the pH change to acidic in water at 60 ℃, the reversible acylhydrazone bond could undergo reversible hydrolysis. During this process, α-cyclodextrins can pass through the dynamic reversible bond and thread onto the polymer chain. Because of the relative strong supramolecular interactions between α-cyclodextrins and ethylene glycol units in water, more and more α-cyclodextrins thread onto the polymer chain, leading to the formation of polyrotaxane. Through the combination of 1H NMR, wide-angle X-ray diffraction, 13C CP/MAS NMR and differential scanning calorimetric tests, the formation of polyrotaxane prepared by dynamic method is confirmed. Differing from the traditional routes, the preparation of pseudo(poly)rotaxane is no longer a prerequisite to construct polyrotaxane in this dynamic method. The novel polyrotaxane with reversible covalent bond, which has its inherent dynamic property, has potential use in smart materials and self-healing materials.

Key words: α-Cyclodextrin, Poly(ethylene glycol), Reversible acylhydrazone bond, pH responsive, Polyrotaxane