Kim, C Lee, SC Kang, SW Kwon, IC Jeong, SY 2024-01-21T13:33:56Z 2024-01-21T13:33:56Z 2021-09-05 2000-09-15 0887-6266 https://pubs.kist.re.kr/handle/201004/141094 Amphiphilic diblock and triblock copolymers of various block compositions based on hydrophilic poly(2-ethyl-2-oxazoline) (PEtOz) and hydrophobic poly(epsilon-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. (C) 2000 John Wiley & Sons, Inc. English JOHN WILEY & SONS INC DIBLOCK COPOLYMERS MICELLAR SOLUTIONS GELATION MICELLIZATION GEL TEMPERATURE SOLUBILITY SYSTEMS OXIDE) WATER Phase-transition characteristics of amphiphilic poly(2-ethyl-2-oxazoline)/poly(epsilon-caprolactone) block copolymers in aqueous solutions Article 10.1002/1099-0488(20000915)38:18<2400::AID-POLB70>3.3.CO;2-Z 1 JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS, v.38, no.18, pp.2400 - 2408 JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS 38 18 2400 2408 scie scopus 000089004200007 2-s2.0-0034273351 Polymer Science Polymer Science Article DIBLOCK COPOLYMERS MICELLAR SOLUTIONS GELATION MICELLIZATION GEL TEMPERATURE SOLUBILITY SYSTEMS OXIDE) WATER amphiphilic diblock and triblock copolymers poly(2-ethyl-2-oxazoline) phase-transition behaviors gel-sol transition precipitation