Phosphorylation of Corn Starch in an Ionic Liquid

Corn starch was phosphorylated by reaction with sodium dihydrogenphosphate or disodium hydrogen phosphate using 1-butyl-3-methylimidazolium chloride (BMIMCI) as reaction medium. The parameters varied included the molar ratio of reactant, reaction time and temperature and were investigated regarding the degree of substitution for the phosphorylated starch. The degree of substitution of starch phosphates prepared ranged from 0.03 to 0.55. The product was characterized by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. It was found that the native crystallinity of corn starch was largely distroyed during the dissolution and functionalization process in the ionic liquid system under the reaction conditions.