A novel approach to grafting polymerization of ε-caprolactone onto starch granules

A new biodegradable starch graft-copolymer, starch-g-poly(ε-caprolatone) (St-g-PCL), was synthesized in situ by the ring-opening graft-polymerization of a ε-caprolactone (CL) monomer onto starch granules in the presence of Sn(Oct)2. The polymerization was carried out in three different polymerization methods: in bulk, in toluene suspension or in suspension/bulk polymerization, where a suspension/bulk process resulted in highest PCL grafting efficiency in 40 wt%. The structure of St-g-PCL was characterized by IR, DSC, SEM and WAXD. Both of the CL monomer and amylose corn starch were of industrial grade, without further purifications. The medium-resistance of St-g-PCL and the mechanical properties of the PCL composite blending with St-g-PCL were better than that of the PCL/starch blending composite.