MACROMOLECULAR ENGINEERING OF POLYLACTONES AND POLYLACTIDES .3. SYNTHESIS, CHARACTERIZATION, AND APPLICATIONS OF POLY(EPSILON-CAPROLACTONE) MACROMONOMERS

Well-defined omega-methacryloylpoly(epsilon-caprolactone) (or PCL) macromonomers have been prepared by using an aluminum alkoxide that bears a methacrylic double bond. The initiator results from the equimolar reaction of triethylaluminum with 2-hydroxyethyl methacrylate (HEMA). The coordination-insertion type of polymerization is living and yields exclusively linear macromonomers of a predictable molecular weight with a narrow molecular weight distribution. IR and H-1 NMR studies show that the methacryloyl group associated with the active alkoxy group of the initiator is selectively attached to one chain end. Should the living polymerization be terminated by methacryloyl chloride, and a alpha,omega-dimethacryloyl-PCL, i.e. a alpha,omega-macromonomer is obtained. PCL macromonomers and HEMA are easily copolymerized in the presence of AIBN, resulting in a hydrophilic poly(HEMA) backbone grafted with hydrophobic PCL subchains.