Syntheses and application of polylactides

Polylactides can be prepared by direct polycondensation of lactic acid, or better, by ring-opening polymerization of cyclic dilactides (usually called lactides). These lactides exist in the form of four stereoisomers two of which (L,L- and rac. -D,L-) are technically produced in large quantities. These lactides can by polymerized via four different classes of initiators and reaction mechanisms. The characteristics mechanistic and preparative features of the cationic polymerization, anionic polymerization and of the coordination-insertion mechanism are described. Furthermore, copolymerizations of lactides with glycolide or epsilon -caprolactone and their analytical problems are discussed. Finally, a new type of wound dressing based on transparent are resorbable films of copolylactides is mentioned. (C) 2001 Published by Elsevier Science Ltd. All rights reserved.