Unimolecular Combination of an Atom Transfer Radical Polymerization Initiator and a Lactone Monomer as a Route to New Graft Copolymers

Abstract

The synthesis, polymerization, and copolymerization of a new cyclic ester, γ-(2-bromo-2-methyl propionyl)-e-caprolactone (3), containing a pendent-activated alkyl bromide functional group is described. This new compound serves as both a monomer for “living” ring-opening polymerization (ROP) as well as an initiator for the controlled atom transfer radical polymerization (ATRP). Three distinctive routes to poly(e-caprolactone)−graft−poly(methyl methacrylate) copolymers were surveyed by either sequential or concurrent living polymerization procedures. The first approach involves the ROP of e-caprolactone with various compositions of 3, followed by the polymerization of methyl methacrylate via ATRP from the activated alkyl bromide sites along the polyester backbone. Alternatively, α-lactone functional methyl methacrylate macromonomers were prepared by ATRP of methyl methacrylate initiated from 3. The macromonomers were copolymerized with e-caprolactone via ROP to form the target graft copolymers. Finally, the...