Chemical modification of pullulan by isocyanate compounds

The modified pullulan derivatives having N-phenylurethane and N-hexylurethane groups in the side-chain (PI-PL and HI-PL) have been synthesized by the reactions of pullulan with phenyl isocyanate (PIC) and hexyl isocyanate (HIC), respectively. The structure of the derivatives was characterized by gel permeation chromatography, IR and 1H NMR spectroscopy. From the measurement of differential scanning calorimetry of PI-PL and HI-PL with various degrees of addition (DA) in the range of 0–3, it was revealed that both the derivatives showed a clear glass transition temperature (Tg), which decreased with the increasing DA of PIC and HIC. The pullulan derivatives were water-resistant and had good solubility in general organic solvents.