Poly(N,N-dimethylacrylamide)-polyethylene (AE) diblock copolymers were synthesized by the combination of living anionic and reversible addition-fragmentation transfer (RAFT) polymerizations. By direct dispersion of the copolymers into water above the melting transition of polyethylene and cooling to 25 °C, disklike micelles were obtained and visualized by cryogenic transmission electron microscopy (cryo-TEM). Spherical micelles were formed from a control noncrystalline poly(N,N-dimethylacrylamide)-poly(ethylene- alt-propylene) (AP) sample with similar composition and overall molecular weight. In combination with differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS), the disklike morphology in AE micelles was ascribed to the crystallization of polyethylene, driving the formation of disklike structures in this stepwise "micellization-crystallization" protocol. Further, as evidenced by small-angle neutron scattering (SANS), chain exchange between micelles was absent at elevated temperature, and thus the crystallization upon cooling was confined within each "frozen" micelle.