A novel amphiphilic branch-ring-branch tadpole-shaped [linear-poly(e-caprolactone)]-b-[cyclic-poly(ethylene oxide)]-b-[linear-poly(e-caprolactone)] [(l-PCL)-b-(c-PEO)-b-(l-PCL)] was synthesized by combination of glaser coupling reaction with ring-opening polymerization (ROP) mechanism. The self-assembling behaviors of (l-PCL)-b-(c-PEO)-b-(l-PCL) and their p-shaped analogs of poly(e-caprolactone)/poly(ethylene oxide)]-b-poly(ethylene oxide)-b-[poly(e-caprolactone)/poly(ethylene oxide) with comparable molecular weight in water were preliminarily investigated. The results showed that the micelles formed from the former took a fiber look, however, that formed from the latter took a spherical look. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012