Macromolecular engineering of polylactones and polylactides. XV. Poly(D,L)‐lactide macromonomers as precursors of biocompatible graft copolymers and bioerodible gels

The functional aluminum alkoxide, Et2AlO(CH2)2O‐C(O)C(CH3)CH2, is a very effective initiator for the (D,L)‐lactide (LA) polymerization in toluene at 707deg;C. The coordination‐insertion type of polymerization is living and exclusively yields linear P (D,L)‐lactide macromonomers of a predictable molecular weight and a narrow molecular weight distribution. IR and 1H‐NMR studies show that the methacryloyl group of the initiator is selectively and quantitatively attached to one chain end, whereas the second extremity is systematically a hydroxyl function resulting from the hydrolysis of the living growing site. α,ω‐Dimethacryloyl‐P(D,L)‐lactides, i.e., α,ω‐macromonomers, have also been successfully synthesized by the additional control of the termination step, i.e., by reaction of Al alkoxide end groups with methacryloyl chloride. α‐Macromonomer and α,ω‐macromonomer P(D,L)‐lactides are easily free‐radical copolymerized with 2‐hydroxyethyl methacrylate (HEMA), resulting in a hydrophilic poly (HEMA) backbone grafted with hydrophobic P(D,L)‐lactide subchains and a biodegradable amphiphilic network, respectively. © 1994 John Wiley & Sons, Inc. Copyright © 1994 John Wiley & Sons, Inc.