AbstractThe biomedical applications of poly(ε‐caprolactone) (PCL) were limited for its high hydrophobicity and crystallinity. In this study, we copolymerized CL with amorphous 5‐hydroxyl‐trimethylene carbonate (HTMC) to solve the problem. The 5‐benzyloxy‐trimethylene carbonate (BTMC) was synthesized to copolymerize with CL, then hydrogenolyzed to obtain hydroxyl pendant groups. A serial of copolymers with different BTMC molar ratio were synthesized and their chemical structures and thermal properties were thoroughly studied with NMR, FT‐IR, GPC, XRD, DSC, and TGA. Finally we examined the water contact angle of the copolymers. DSC and XRD results showed that the PCL segments in the copolymers crystallized below 16.8%. BTMC molar content and the crystallinity of the copolymers increased after hydrolysis. With the introduced hydroxyl pendant groups, the deprotected copolymers improved their hydrophilic property significantly, and the copolymer with 9.3% HTMC molar content had static water contact angle as low as 36.5°. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012