SYNTHESIS AND ENZYMATIC-HYDROLYSIS OF LACTIC-ACID DEPSIPEPTIDE COPOLYMERS WITH FUNCTIONALIZED PENDANT GROUPS

Since poly(lactic acid) is the biodegradable polyester having low immu nogenicity and good biocompatibility, it is utilized as a medical mate rial. However, poly(lactic acid) is a water-insoluble crystalline poly mer having no reactive side-chain group. Thus, the use of poly(lactic acid) is limited. To modify the properties of poly(lactic acid) and to introduce the functionalized pendant groups to poly(lactic acid), we synthesized two kinds of lactic acid-depsipeptide copolymers with reac tive pendant groups, namely poly[LA-(Glc-Lys)] and poly[LA-(Glc-Asp)l. This was done through ring-opening copolymerizations of L-lactide wit h the corresponding protected cyclodepsipeptides, cyclo[Glc-Lys(Z)] an d cyclo[Glc-Asp(OBzl)], and subsequent deprotection of benzyloxycarbon yl and benzyl groups, respectively. By changing the mole fraction of t he corresponding depsipeptide units, the solubility, thermal transitio n and degradation behavior of the modified poly(lactic acid) could be varied. (C) 1997 John Wiley & Sons, Inc.