Star-shaped hydroxy-terminated poly(epsilon-caprolactone)s (ssPCL), with arms of different lengths, were obtained by ring-opening polymerization (ROP) of epsilon-caprolactone initiated by pentaerythritol, and were condensed with alpha-methyl-omega-(3-carboxypropionyloxy)-poly(ethylene oxide)s ((M) over barn = 5550-5000) to afford four-armed PCL-PEO star diblock copolymers (ssPCL-PEO). The polymers were characterized by H-1 and C-13 NMR spectroscopy and size-exclusion chromatography (SEC). The melting behavior of ssPCLs was studied by differential scanning calorimetry (DSC). X-ray diffraction and DSC techniques were used to investigate the crystalline phases of ssPCL-PEOs.