Substitution of corn starch with polycaprolactone via chlorination and water resistance of the substituted starch

Corn starch was chlorinated using methanesulfonyl chloride in dimethylforma mide (DMF) and then substituted with polycaprolactone (PCL) in various solv ents [dimethylsulfoxide (DMSO), water and dimethylacetamide (DMAc)] contain ing a catalyst [sodium hydroxide (NaOH) or lithium chloride (LiCl)] to impr ove water resistance. The reaction yield based on the product weight was hi ghest (85%) when DMAc and LiCl were used. Fourier transform infrared (FTIR) spectra showed that starch was monosubstituted with PCL in the aqueous NaO H solution, whereas it was to crosslink by PCL in the case using DMAc and L lCl. The intrinsic viscosity of the products in DMSO supports these trends. By introducing the hydrophobic PCL onto starch, solvent resistance of the substituted starches to water and other aqueous media increased. The crossl inked starch displayed higher water resistance than the monosubstituted sta rch. (C) 2001 John Wiley & Sons, Inc.