The dynamic mechanical and structural properties of polymeric micelles, formed by hydrophobically end-capped poly(ethylene oxide) (PEO) in water, were studied as a function of concentration and temperature. A discontinuous liquid-solid transition is observed during a temperature quench at a critical temperature (T-c) that increases with increasing micelle concentration. The transition is fast except after a quench to a temperature just below T-c where it may take as long as 24 h. A body-centered-cubic phase is formed relatively quickly after the liquid-solid transition, i.e., in the jammed system. The fraction of crystalline material in the solid increases with increasing concentration or decreasing temperature. The viscosity of the liquid phase has a power law concentration dependence similar to that of polymer stars with a relatively small numbers of arms.