[해외논문]
Phase-transition characteristics of amphiphilic poly(2-ethyl-2-oxazoline)/poly(ϵ-caprolactone) block copolymers in aqueous solutions
Journal of polymer science Part B, Polymer physics ,
v.38 no.18 ,
2000년, pp.2400 - 2408
Kim, Chulhee
(Department of Polymer Science and Engineering, Inha University, Inchon 402-751, Korea)
,
Lee, Sang Cheon
(Department of Polymer Science and Engineering, Inha University, Inchon 402-751, Korea)
,
Kang, Suk Won
(Department of Polymer Science and Engineering, Inha University, Inchon 402-751, Korea)
,
Kwon, Ick Chan
(Biomedical Research Center, Korea Institute of Science and Technology, 39-1 Hwawolkok-dong, Songbuk-Ku, Seoul 136-791, Korea)
,
Jeong, Seo Young
(Biomedical Research Center, Korea Institute of Science and Technology, 39-1 Hwawolkok-dong, Songbuk-Ku, Seoul 136-791, Korea)
Amphiphilic diblock and triblock copolymers of various block compositions based on hydrophilic poly(2-ethyl-2-oxazoline) (PEtOz) and hydrophobic poly(ϵ-caprolactone) were synthesized. The micelle formation of these block copolymers in aqueous media was confirmed by a fluorescence technique and...
Amphiphilic diblock and triblock copolymers of various block compositions based on hydrophilic poly(2-ethyl-2-oxazoline) (PEtOz) and hydrophobic poly(ϵ-caprolactone) were synthesized. The micelle formation of these block copolymers in aqueous media was confirmed by a fluorescence technique and dynamic light scattering. The critical micelle concentrations ranged from 35.5 to 4.6 mg/L for diblock copolymers and 4.7 to 9.0 mg/L for triblock copolymers, depending on the block composition. The phase-transition behaviors of the block copolymers in concentrated aqueous solutions were investigated. When the temperature was increased, aqueous solutions of diblock and triblock copolymers exhibited gel–sol transition and precipitation, both of which were thermally reversible. The gel–sol transition- and precipitation temperatures were manipulated by adjustment of the block composition. As the hydrophobic portion of block copolymers became higher, a larger gel region was generated. In the presence of sodium chloride, the phase transitions were shifted to a lower temperature level. Sodium thiocyanate displaced the gel region and precipitation temperatures to a higher temperature level. The low molecular weight saccharides, such as glucose and maltose, contributed to the shift of phase-transition temperatures to a lower temperature level, where glucose was more effective than maltose in lowering the gel–sol transition temperatures. The malonic acid that formed hydrogen bonds with the PEtOz shell of micelles was effective in lowering phase-transition temperatures to 1.0M, above which concentration the block copolymer solutions formed complex precipitates. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2400–2408, 2000
Amphiphilic diblock and triblock copolymers of various block compositions based on hydrophilic poly(2-ethyl-2-oxazoline) (PEtOz) and hydrophobic poly(ϵ-caprolactone) were synthesized. The micelle formation of these block copolymers in aqueous media was confirmed by a fluorescence technique and dynamic light scattering. The critical micelle concentrations ranged from 35.5 to 4.6 mg/L for diblock copolymers and 4.7 to 9.0 mg/L for triblock copolymers, depending on the block composition. The phase-transition behaviors of the block copolymers in concentrated aqueous solutions were investigated. When the temperature was increased, aqueous solutions of diblock and triblock copolymers exhibited gel–sol transition and precipitation, both of which were thermally reversible. The gel–sol transition- and precipitation temperatures were manipulated by adjustment of the block composition. As the hydrophobic portion of block copolymers became higher, a larger gel region was generated. In the presence of sodium chloride, the phase transitions were shifted to a lower temperature level. Sodium thiocyanate displaced the gel region and precipitation temperatures to a higher temperature level. The low molecular weight saccharides, such as glucose and maltose, contributed to the shift of phase-transition temperatures to a lower temperature level, where glucose was more effective than maltose in lowering the gel–sol transition temperatures. The malonic acid that formed hydrogen bonds with the PEtOz shell of micelles was effective in lowering phase-transition temperatures to 1.0M, above which concentration the block copolymer solutions formed complex precipitates. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2400–2408, 2000
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