Preparation of biodegradable polylactide-co-poly(ethylene glycol) copolymer by lactide reacted poly(ethylene glycol)

Poly-DL-lactide-poly (ethylene glycol)-poly-D, L-lactide triblock copolymer (PELA) was synthesized with the initiator of potassium poly (ethylene glyc ol)ate. The effects of various factors, such as amount of solvent and initi ator, reaction time and temperature, sort of solvent and molecular weight o f poly (ethylene glycol) (PEG)on the polymerization reaction were investiga ted. The polymerization was conducted in the super-saturated solution of mo nomer and monomer was successively dissolved and polymerized. 'Therefore th e reaction rate was controlled by the dissolving rate. An effort to solve p olymerization of DL-lactide in THF initiated by potassium poly (ethylene gl ycol)ate with relatively low molecular weight of PEG was made. The copolyme rs were characterized by GPC, DSC, IR and H-1-NMR. (C) 1999 Elsevier Scienc e Ltd. All rights reserved.