Preparation and Solution Behavior of a Thermoresponsive Diblock Copolymer of Poly(ethyl glycidyl ether) and Poly(ethylene oxide)
| Autor: | Shin-ichiro Imabayashi, Michihiro Ogura, Masayoshi Watanabe, Hiroyuki Tokuda |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Hydrodynamic radius
Ethylene oxide Polymers Chemistry Temperature Water Ether Surfaces and Interfaces Condensed Matter Physics Micelle Ring-opening polymerization Phase Transition Polyethylene Glycols Molecular Weight Solutions chemistry.chemical_compound Dynamic light scattering Polymerization Spectrophotometry Polymer chemistry Electrochemistry Copolymer General Materials Science Spectroscopy Ethers |
| Zdroj: | Langmuir. 23:9429-9434 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/la701384q |
| Popis: | A thermoresponsive diblock copolymer, poly(ethyl glycidyl ether)-block-poly(ethylene oxide) (PEGE-b-PEO), is synthesized by successive anionic ring-opening polymerization of ethyl glycidyl ether and ethylene oxide using 2-phenoxyethanol as a starting material, and its solution behavior is elucidated in water. In a dilute 1 wt % solution, the temperature-dependent alteration in the polymer hydrodynamic radius (RH) is measured in the temperature range between 5 and 45 degrees C by pulse-gradient spin-echo NMR and dynamic light scattering. The RH value increased with temperature in two steps, where the first step at 15 degrees C corresponds to the core-shell micelle formation and the second step at 40 degrees C corresponds to the aggregation of the core-shell micelles. The formation of the core-shell micelles is supported by the solubilization of a dye (1,6-diphenyl-1,3,5-hexatriene) in the hydrophobic core, which is recognized for a copolymer solution in the temperature range between 20 and 40 degrees C. In this temperature range, the core-shell micelles and the unimers coexist and the fraction of the former gradually increases with increasing temperature, suggesting equilibrium between the micelles and the unimers. In the concentrated regime (40 wt % solution), the solution forms a gel and the small-angle X-ray scattering measurements reveal the successive formation of hexagonal and lamellar liquid crystal phases with increasing temperature. |
| Databáze: | OpenAIRE |
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