Structural control of poly(methyl methacrylate)-g-poly(lactic acid) graft copolymers by atom transfer radical polymerization (ATRP)

Atom transfer radical copolymerization of methyl methacrylate (MMA) and (meth)acrylate-terminated poly(lactic acid) (PLA) macromonomers was investigated. The relative reactivity of methacrylate-terminated macromonomer (1/r(MMA) = 1.75) and acrylate-terminated macromonomer (1/r(MMA) = 0.61) was close to that of 2-hydroxyethyl methacrylate and 2-hydroxyethyl acrylate, respectively. The difference in reactivity in ATRP and conventional radical polymerization is discussed in terms of the diffusion control effect. A mixture of methacrylate-terminated macromonomer and acrylate-terminated macromonomer was copolymerized with MMA by ATRP to give a homogeneously branched PMMA-g-PLA graft copolymer with low polydispersity (M-w/M-n = 1.15).