Study Of Schiff Base Catalyst On Ring-opening Polymerization Of Lactide

Polylactide is a very important kind of polymer material.Because of its excellent biocompatibility and biodegradability,it has been used in the fields of packaging material,controllable drug carrier and tissue engineering stent.The ring-opening polymerization of lactide is the most classical and versatile method for the synthesis of poly lactide,which has been widely used for its excellent controllability.In the past decades,Schiff base catalysts have been widely studied in the application of the ring-opening polymerization of lactide.The excellent performance of the catalyst with excellent stereo selectivity has been widely confirmed.We prepared a series of ligand compounds by using the salicylaldehyde derivative and amine,and a series of single metal center cobalt catalysts.In addition,a series of single metal center zinc catalysts were prepared by using zinc silylamido complexes and aza(oxazoline).The catalytic properties were studied by using the polymerization of lactide with left-and right-handed enantiomers,and racemic lactide.The factors which affect the polymerization rate in the catalysts were discussed.Four factors,such as flexibility of the ligand amine bridge,the valence state of the central metal atom,the ratio of the cocatalyst and the solvent water content have played the improtant roles on the polymerization rate of the catalyst.We also found that the polymerization products have an isotactic selectivity.The end group analysis indicated that the real initiator of the polymerization reaction is PO(propylene oxide).