Segmented terpolymers, poly(alkyl methacrylate)-g-POIY(D-lactide)/Poly-(dimethylsiloxane) (PLA/PDMS), were prepared with a combination of the "grafting through" technique (macromonomer method) and controlled/living radical polymerization (atom transfer radical polymerization or reversible addition-fragmentation transfer polymerization). Two synthetic pathways were used. The first was a single-step approach in which a low-molecular-weight methacrylate monomer (methyl methacrylate or butyl methacrylate) was copolymerized with a PLA macromonomer and a PDMS macromonomer. The second strategy was a two-step approach in which a graft copolymer containing one macromonomer was chain-extended by a copolymerization of the second macromonomer and the low-molecular-weight methacrylate. The kinetics of both synthetic approaches were investigated, showing that the polymerizations exhibited a controlled/living behavior. Furthermore, the molecular structure of the terpolymers (composition, molecular weight distribution, and microstructure) was investigated by two-dimensional liquid chromatography. Well-defined terpolymers with controlled branch distribution, composition (F-w,F-PMMA/F-w,F-PLA/F-w,F-PDMS similar to 50/30/20) molecular weight (M-n similar to 50,000 g . mol(-1)), and a narrow molecular weight distribution (M-w/M-n similar to 1.3) were prepared via both pathways. (C) 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1939-1952, 2004.