Preparation and characterization of a novel responsive hydrogel with a β-cyclodextrin-based macromonomer

Based on a combination of poly(N-isopropylacrylamide), which could respond to an external temperature, and β-cyclodextrin (β-CD), which could form a molecular inclusion complex, a novel hydrogel, having both thermal and pH sensitivities and containing β-CD and N-isopropylacrylamide (NIPA) segments, was synthesized. For the incorporation of β-CD into the polymer network, a macromonomer was prepared first by the reaction of a β-CD-based polymer with maleic anhydride in dimethylformamide and then by copolymerization with NIPA in an aqueous solution. Elemental analysis, IR spectroscopy, differential scanning calorimetry, and swelling measurements were employed for the characterization of the hydrogel chain structure and its physical properties. With methyl orange as a model compound in inclusion tests, it was found that the hydrogel not only possessed a remarkable supramolecular inclusion ability (with respect to that of the small molecule cyclodextrin) but also could sensitively respond to various external stimuli, including the temperature, pH, and ionic strength. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 361–367, 2003