The six-arm star-shaped amphiphilic block copolymers poly(-caprolactone)-b-poly(2-hydroxyethyl methacrylate) (6sPCL-b-PHEMA) were prepared by a combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP).The synthesis procedure was composed of three step reactions:First

6sPCL homopolymers were prepared via ring-opening polymerization of -caprolactone by using dipentaerythritol with 6 hydroxyl functional groups as an initiator; Second

6sPCL was functionalized to get macroinitiator 6sPCL-Br for ATRP; Third

atom transfer radical polymerization of 2-hydroxyethyl methacrylate (HEMA) from the macroinitiator 6sPCL-Br was conducted by using copper (Ⅰ) bromide ( Cu(I)Br) and 2

2'-bipyredine (Bpy) as catalyze system to synthesize the star block copolymer 6sPCL-b-PHEMA.Molecular structure of 6sPCL-b-PHEMA was confirmed by 1H nuclear magnetic resonance (1H-NMR) and Fourier transform infrared (FTIR) spectroscopy.Thermal behavior and hydrophilicity of obtained 6sPCL-b-PHEMA were measured by DSC and water contact angle

respectively.The melting point (Tm)

crystallization temperature (Tc) and crystallinity (Xc) of the 6sPCL-b-PHEMA were reduced with an increasing of the length of the PHEMA block until the polymers changed into amorphous

in addition

the hydrophilicity of the polymers increased visibly.