Preparation of poly(ethylene glycol)-block-poly(caprolactone) copolymers and their applications as thermo-sensitive materials

✍ Scribed by Kim, Moon Suk ;Seo, Kwang Su ;Khang, Gilson ;Cho, Sun Hang ;Lee, Hai Bang

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 112 KB
• Volume: 70A
• Category: Article
• ISSN: 0021-9304
• DOI: 10.1002/jbm.a.30049

✦ Synopsis

The polymerization of epsilon-caprolactone (epsilon-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. Et2O as a monomer activator. The molecular weights of the poly(epsilon-caprolactone) (PCL) in MPEG-PCL diblock copolymers controlled with the feed ratio of epsilon-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 degrees 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.