Heterogeneous ring-opening polymerization of lactones for biomedical applications

Catalysis of the ring-opening reaction of L-lactide and epsilon-caprolactone to form the corresponding biodegradable polyesters is frequently performed using organometallic compounds such as tin(II) 2-ethylhexanoate, which operates by a living, coordination insertion mechanism. For biomedical applications, non-toxic calcium salts have been researched but these rarely approach the same efficiency. The use of heterogeneous immobilized catalysts offers an alternative approach, but competing reactions such as transesterification affect the final molecular weight and polydispersity. The formation of hybrid materials by using silica as the initiation site offers the prospect of biomaterials with novel properties. (C) 2009 Society of Chemical industry