Synthesis and characterization of novel block copolymer from trans ‐4‐hydroxy‐ L ‐proline and poly(ethylene glycol)

A series of novel ABA‐type block copolymers were synthesized by polymerization of trans ‐4‐hydroxy‐ L ‐proline (HyP) in the presence of various molecular weight poly(ethylene glycol)s (PEGs), a bifunctional OH‐terminated PEG using stannous octoate as catalyst. The optimal reaction conditions for the synthesis of the copolymers were obtained with 5 wt % stannous octoate at 140°C under vacuum (20 mmHg) for 24 h. The synthesized copolymers were characterized by IR spectroohotometry, proton nuclear magnetic resonance, differential scanning calorimetry, and Ubbelohde viscometer. The glass transition temperature ( T g ) of the copolymers shifted to significantly higher temperature with increasing the number average degree of polymerization and HyP/PEO molar ratio. In contrast, the melting temperature ( T m ) decreased with increasing the HyP/PEO molar ratio. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1581–1587, 2001