Microwave-assisted solvent-free or aqueous-based synthesis of biodegradable polymers

Microwave radiation was used as the energy source for various types of chemical derivatizations of polysaccharides and for the synthesis of biodegradable polyesters in solvent-free or aqueous-based reaction systems. A medium to high degree of substitution was obtained for starch acetates, starch succinates, carboxymethyl konjac, aminated starch, and aminated chitosan. Ring-opening polymerization of lactide and epsilon-caprolactone proceeded rapidly even at low power output in the presence of tin octanoate catalyst. Complete monomer conversion and high molecular weight were achieved in less than 6 minutes under nonisothermal conditions. The yield rapidly increased with increasing power output and showed no significant change in a wide range of batch sizes. Polycaprolactone was successfully grafted from starch and konjac acetate in 3 minutes, yielding as high as 24% grafting efficiency and 25% grafting degree.