Macromolecular engineering of polylactones and polylactides. XXV. Synthesis and characterization of bioerodible amphiphilic networks and their use ascontrolled drug delivery systems

Well-defined alpha,omega-methacryloyl poly-epsilon-caprolactone (PCL) and p oly(D,L)-lactide P(D,L)LA dimacromonomers have been synthesized by living r ing-opening polymerization of the parent monomers initiated by diethylalumi num 2-hydroxyethylmethacrylate (Et2Al-O-(CH2)(2)-O-C(O)-C(CH3)=CH2) and ter minated by reaction of the propagating Al alkoxide groups with methacryloyl chloride. These dimacromonomers have been copolymerized with a hydrophilic comonomer, i.e., 2-hydroxyethylmethacrylate, in bulk at 65 degrees C by us ing benzoyl peroxide as a free-radical initiator. The swelling ability of t he amphiphilic PHEMA/PCL or P(D,L)LA networks has been investigated in both aqueous and organic media. Effect of network composition and molecular wei ght of the dimacromonomer on the swelling kinetics and the equilibrium solv ent uptake has been studied. Lipophilic dexamethasone acetate and the hydro philic sodium phosphate counterpart have been incorporated into the amphiph ilic gels and their release has been studied in relation to the gel charact eristics. (C) 1999 John Wiley & Sons, Inc.