Immobilization of β-Cyclodextrin as Insoluble β-Cyclodextrin Polymer and Its Catalytic Performance

Insoluble β-cyclodextrin polymers were prepared from β-cyclodextrin (β-CD) using epichlorohydrin (EPI) as crosslinking agent under basic conditions. The polymers were characterized by Fourier Transform Infrared (FTIR), Thermogravimetry (TG), X-ray diffraction (XRD) and TG-FTIR. The results demonstrated that the polymerization between EPI and β-CD indeed occurred, and a number of CD rings were interconnected to form a three-dimensional network. Moreover, different factors influencing the polymerization, e.g. molar ratio of EPI to β-CD, the concentration of NaOH and reaction temperature, have been investigated. The polymer prepared under the optimal conditions (the molar ratio EPI: β-CD of 44, the NaOH concentration 50% in mass, and the temperature at 65 °C) showed excellent thermal stability and insolubility in organic solvents or strong acid/base. In addition, the β-cyclodextrin polymers also presented high catalytic activity for aqueous oxidation of benzyl alcohol with hypochlorite as oxidant.