Autonomous Shrinking/Swelling Phenomenon Driven By Macromolecular Interchain Cross-Linking via β-Cyclodextrin-Triazole Complexation

Molecular recognition-induced autonomous dynamic motions, which feature in living systems, have been attracting much interest because such biological functions can promote the consequent development of sophisticated functional materials. To realize molecular recognition-induced autonomous dynamic motions using synthetic materials and manipulate them, herein, we designed poly(NIPAM-co-triaz-CD), which bears a cyclodextrin (CD) host and a triazole guest in the side chains of the polymer itself; subsequently, we investigated its phase transition behavior. 2D NOESY NMR analysis evidenced that triazole in the polymer side chains was included into the CD cavity, and DLS measurements indicated that the CD triazole complexation resulted in the formation of interchain cross-linking. Poly(NIPAM-co-triaz CD) exhibited autonomous shrinking/swelling of the polymer chains that occurred by itself in water due to the interchain cross-linking via the CD triazole complexation. Thus, this study enabled the poly(NIPAM) itself to generate the artificial molecular recognition-induced autonomous phenomenon. These findings not only present a unique methodology for polymer phase transition phenomena but also provide a new platform for designing molecular recognition polymeric materials.