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

Abstract

Abstract The functional aluminum alkoxide, Et 2 AlO(CH 2 ) 2 O‐C(O)C(CH 3 )CH 2 , 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 1 H‐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 &amp; Sons, Inc.