Ring-Opening Polymerization of Cyclic Esters Lactones

Ring-Opening Polymerization of Cyclic Esters (Lactones) 

Cyclic esters of oo-hydroxycarboxylic acids can be polymerized by ring-opening to give linear aliphatic polyesters. According to the type of initiator and monomer the polymerization occurs either by alkyl or by acyl cleavage  

The polymerizability depends on the ring size and on the number, size, and position of the substituents. 

The ring-opening polymerization of dilactide (dimeric cyclic ester of lactic acid) allows the preparation of high molecular weight, optically active polyesters of lactic acid. The configuration of the asymmetric carbon atoms of the monomer is retained when the polymerization is initiated with SnCl4 or Et2Zn, for example  

Ring-Opening Polymerization of Dilactide with Cationic Initiators in Solution 

---