Temperature-sensitive hydrophilic/ hydrophobic multi-arm block copolymer hydrogel온도민감성 친수성/소수성 multi-arm 블록 공중합체의 하이드로겔에 관한 연구

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In this study, temperature-sensitive biodegradable multi-arm $poly((_{DL}-lactide-co-glycolide)-b-ethylene glycol)$ (multi-arm PLGA-PEG) and four-arm poly $(ethylene glycol-b-(_{DL}-lactide-co-glycolide))$ (4arm PEG-PLGA) block copolymers were synthesized to study the effect of the molecular architecture and composition on the gelation and micellization behaviors in aqueous solution. In chapter 1, three types of multi-arm (3arm, 4arm, and 6arm) PLGA-PEG block copolymers were prepared by the coupling reaction of multi-arm PLGA and CMPEG. The successful syntheses and molecular weights of multi-arm PLGA, CMPEG and multi-arm PLGA-PEG were confirmed by ${^1}H-NMR$. The PLGA length, the relative hydrophobicity in PLGA block, and the PEG length in multi-arm PLGA-PEG were varied by the mole ratio of $_{DL}-lactide$, glycolide, and multifunctional initiator and by the molecular weight of PEG. The synthesized multi-arm PLGA-PEG aqueous solutions showed micellization at low concentration and sol-gel-sol transition at high concentration. As the PLGA block length, the ratio of lactide to glycolide, and the number of arms increased, the sol-gel transition curve shifted to the left and critical gel concentration (CGC) decreased due to the increase of hydrophobicity. In viscosity measurement, the temperature at which the viscosity changed abruptly was in good agreement with phase transition temperature by the tube-tilting method. Viscosity was also increased with increasing the polymer concentration, the ratio of lactide to glycolide, the PLGA length, and the number of arms. This increase in gel strength is due to the enhanced integrity of gels caused by the increased hydrophobic interaction and covalent-bond. Multi-arm block copolymers with longer PLGA, stronger hydrophobicity in PLGA, and more arms formed micelles at lower concentration and their formed micelle aggregated larger micelle groups with increasing temperature, which was also evidenced by the population of mice...
Advisors
Kim, Sung-Chulresearcher김성철researcher
Description
한국과학기술원 : 생명화학공학과,
Publisher
한국과학기술원
Issue Date
2008
Identifier
295353/325007  / 020045194
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 생명화학공학과, 2008.2, [ xi, 104 p. ]

Keywords

drug delivery; hydrogel; temperature-sensitive; star polymer; 약물전달; 하이드로겔; 온도민감성; 스타형 고분자; drug delivery; hydrogel; temperature-sensitive; star polymer; 약물전달; 하이드로겔; 온도민감성; 스타형 고분자

URI
http://hdl.handle.net/10203/29258
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=295353&flag=dissertation
Appears in Collection
CBE-Theses_Ph.D.(박사논문)
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