ANIONIC-POLYMERIZATION OF L-LACTIDE EFFECT OF LITHIUM AND POTASSIUM AS COUNTERIONS

The polymerization of L-lactide was carried out with t-BuOK and t-BuOL i in the presence and absence of crown ethers. Each polymerization sho wed living nature only in the limited sense of having a decreasing amo unt of active species at high conversion. The initiator efficiency was lour in each case because of the deprotonation reaction between the t ert-butoxide ion and L-lactide. Although termination did not take plac e with lithium containing initiators to 90% conversion, intra- and int ermolecular transesterification was observed to a significant degree. With potassium containing initiators both termination and transesterif ication occurred.