title: Preparation of poly(ethylene glycol)-block-poly(caprolactone) copolymers and their applications as thermo-sensitive materials.
abstract: 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.
authors.affiliation: Nanobiomaterials Laboratory, Korea Research Institute of Chemical Technology, P.O. Box 107, Yuseong, Daejeon 305-600, Korea.
authors.forename: Moon Suk
authors.initials: MS
authors.lastname: Kim
authors.forename: Kwang Su
authors.initials: KS
authors.lastname: Seo
authors.forename: Gilson
authors.initials: G
authors.lastname: Khang
authors.forename: Sun Hang
authors.initials: SH
authors.lastname: Cho
authors.forename: Hai Bang
authors.initials: HB
authors.lastname: Lee
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D004337:Drug Carriers; D005027:Ethylene Oxide; D005782:Gels; D006358:Hot Temperature; D006851:Hydrochloric Acid; D007202:Indicators and Reagents; D007279:Injections, Subcutaneous; D009682:Magnetic Resonance Spectroscopy; D011091:Polyesters / Q000138:chemical synthesis*; D011092:Polyethylene Glycols / Q000138:chemical synthesis*; D011108:Polymers / Q000138:chemical synthesis; D051381:Rats; D012996:Solutions
chemical_list: D001672:Biocompatible Materials; D004337:Drug Carriers; D005782:Gels; D007202:Indicators and Reagents; D011091:Polyesters; D011108:Polymers; D012996:Solutions; C016240:polycaprolactone; D011092:Polyethylene Glycols; D005027:Ethylene Oxide; D006851:Hydrochloric Acid