Linear and star-like amphiphilic diblock copolymers were synthesized by the ring-opening polymerization of epsilon-caprolactone and gamma-2-[2-(2-methoxyethoxy) ethoxy] ethoxy-epsilon-caprolactone monomers using zinc undecylenate as a catalyst. These polymers have potential applications as micellar drug delivery vehicles, therefore the properties of the linear and 4-arm star-like structures were examined in terms of their molecular weight, viscosity, thermodynamic stability, size, morphology, and drug loading capacity. Both the star-like and linear block copolymers showed good thermodynamic stability and degradability. However, the star-like polymers were shown to have increased stability at lower concentrations with a critical micelle concentration (CMC) of 5.62 x 10(-4) g L-1, which is less than half the concentration of linear polymer needed to form micelles. The star-like polymeric micelles showed smaller sizes when compared with their linear counterparts and a higher drug loading capacity of doxorubicin, making them better suited for drug delivery purposes. (C) 2016 Wiley Periodicals, Inc.