A series of well-defined amphiphilic diblock copolymers consisting of hydrophobic polyisobutylene (PIB) and hydrophilic poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) segments was synthesized via the combination of living carbocationic polymerization and reversible addition fragmentation chain transfer (RAFT) polymerization. Living carbocationic polymerization of isobutylene followed by end-capping with 1,3-butadiene was first performed at -70 degrees C to give a well-defined allyl-Cl-terminated PIB with a low polydispersity (M-w/M-n =1.29). This end-functionalized PIB was further converted to a macromolecular chain transfer agent for mediating RAFT block copolymerization of 2-(diethylamino)ethyl methacrylate at 60 degrees C in tetrahydrofuran to afford the target well-defined PIB-b-PDEAEMA diblock copolymers with narrow molecular weight distributions (M-w/M-n 1.22). The self-assembly behavior of these amphiphilic diblock copolymers in aqueous media was investigated by fluorescence spectroscopy and transmission electron microscope, and furthermore, their pH-responsive behavior was studied by UV-vis and dynamic light scattering. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1478-1486