Polyisobutylene-b-poly(N,N-diethylacrylamide) (PIB-b-PDEAAm) well-defined amphiphilic diblock copolymers were synthesized by sequential living carbocationic polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization. The hydrophobic polyisobutylene segment was first built by living carbocationic polymerization of isobutylene at -70 degrees C followed by multistep transformations to give a well-defined (M-w/M-n=1.22) macromolecular chain transfer agent, PIB-CTA. The hydrophilic poly(N,N-diethylacrylamide) block was constructed by PIB-CTA mediated RAFT polymerization of N,N-diethylacrylamide at 60 degrees C to afford the desired well-defined PIB-b-PDEAAm diblock copolymers with narrow molecular weight distributions (M-w/M-n 1.26). Fluorescence spectroscopy, transmission electron microscope, and dynamic light scattering (DLS) were employed to investigate the self-assembly behavior of PIB-b-PDEAAm amphiphilic diblock copolymers in aqueous media. These diblock copolymers also exhibited thermo-responsive phase behavior, which was confirmed by UV-Vis and DLS measurements. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1143-1150