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Preparation of poly(ethylene glycol)‐ block ‐poly(caprolactone) copolymers and their applications as thermo‐sensitive materials
Author(s) -
Kim Moon Suk,
Seo Kwang Su,
Khang Gilson,
Cho Sun Hang,
Lee Hai Bang
Publication year - 2004
Publication title -
journal of biomedical materials research part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.849
H-Index - 150
eISSN - 1552-4965
pISSN - 1549-3296
DOI - 10.1002/jbm.a.30049
Subject(s) - copolymer , materials science , ethylene glycol , polymerization , polymer chemistry , caprolactone , monomer , polymer , chain transfer , chemical engineering , radical polymerization , composite material , engineering
The polymerization of ϵ‐caprolactone (ϵ‐CL) was initiated by the terminal alcohol of methoxy poly(ethylene glycol) (MPEG) as an initiator via activated ring‐opening polymerization in the presence of HCl · Et 2 O as a monomer activator. The molecular weights of the poly(ϵ‐caprolactone) (PCL) in MPEG–PCL diblock copolymers controlled with the feed ratio of ϵ‐CL to MPEG. The polymerization was preceded by living fashion with no termination or chain transfer. This polymerization procedure offered MPEG–PCL diblock copolymers with well‐defined structures. The gel‐to‐sol transitions of MPEG–PCL diblock copolymer solutions were also examined. The diblock copolymers synthesized with various MPEG and PCL lengths were dissolved in water at 80°C in various concentrations. The polymer solutions formed gel at room temperature. The formed gel became fluids again by increasing the temperature. The gel‐to‐sol transition showed strong dependence on the length of the MPEG and PCL diblock segments. When the polymer solution was injected into rat, it became a gel at body temperature. The formed gel maintained for 1 month. We confirmed that MPEG–PCL diblock copolymers with well‐defined structures served as new thermo‐sensitive biomaterials. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 154–158, 2004