Atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP) were combined to synthesize poly(epsilon-caprolactone-co-octadecyl methacrylate-co-dimethylaminoethyl methacrylate) copolymers possessing a triblock or random block structure. Various synthetic pathways (sequential or simultaneous approaches) were investigated for the synthesis of both copolymers. For the preparation of these copolymers, an initiator with dual functionality for ATRP/anionic ring-opening polymerization, 2-hydroxyethyl 2-bromoisobutyrate, was used.. Copolymers were prepared with good structural control and low polydispersities (weight-average molecular weight/number-average molecular weight < 1.2), but one limitation was identified: the dimethylaminoethyl methacrylate (DMAEMA) block had to be synthesized after the E-caprolactone block. ROP could not proceed in the presence of DMAEMA because the complexation of the amine groups in poly(dimethylaminoethyl methacrylate) deactivated tin(II) hexanoate, which was used as a catalyst for ROP. (c) 2005 Wiley Periodicals, Inc.