Polymerization of β-cyclodextrin with maleic anhydride and structural characterization of the polymers

β-Cyclodextrin (β-CD) polymers were prepared by cross-linking β-CD with maleic anhydride (MA) in anhydrous N,N-dimethyl formamide (DMF) in the presence of NaH. The weight-average molecular weight (M_w) and the chemical structure of the polymers were determined using high performance size exclusion chromatography (HPSEC) with refractive index (RI) and multiangle laser-light scattering (MALLS) detectors, and ¹H NMR spectroscopy. The molecular weight of the polymer increased as the reaction temperature was raised. With a reaction of 4 h at 130 °C at a molar ratio of 1:7:7 for β-CD:NaH:MA, the reaction products were water-insoluble, and contained major polymer fractions with M_w greater than 200 kDa. Smaller and water-soluble polymer fractions were produced at 100 °C or lower reaction temperature. ¹H-NMR spectra revealed that the CD polymers contained both mono- and diesters of butenedioic acid, and diesters became prevalent as the reaction time and temperature were raised.