Polylactide (PLA) is an aliphatic polyester composed of lactide (LA) repeat units. It is the biodegradable and biocompatible material and has attracted much attention recently for the biomedical

pharmaceutical and environmental applications. The review summarizes recent developments in the catalytic polymerization of lactide. Emphasis is placed on the new initiators/catalysts for the ring opening polymerization (ROP) of lactide. Single-site that has high rates or stereocontrol catalysts is provided. Because the stereochemistry of monomeric units in the polymer chains plays a decisive role in the mechanical

physical and degradation proterties of PLA materials

Different polylactide architectures

namely stereoregular PLLA and PDLA

atactic

heterotactic

syndiotactic and stereoblock PLAs are produced depending on the catalysts and the LA monomers used. In this review

we mainly focus on single site catalysts

including aluminum

rare earth metal and the environmentally friendly iron

zinc

magnesium and nonmetallic catalysts for the stereoselective polymerization of lactide. Catalysts displaying low toxicity and biocompatibility are emphasized. It can be reasonably anticipated that the synthesis and practical applications of environmentally friendly PLA will keep increasing at the industrial scale. In this respect

further development in the stereocontrolled ROP of lactide using well-defined single site complexes and nonmetallic catalytic systems will be an attract topic.