| Project/Area Number |
17550137
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional materials chemistry
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| Research Institution | Tokyo University of Science |
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Principal Investigator |
ABE Masahiko Tokyo University of Science, Faculty of Sci. and Tech., Professor (40089371)
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| Co-Investigator(Kenkyū-buntansha) |
土屋 好司 東京理科大学, 理工学部, 客員研究員 (50398822)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,810,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Surfactant / Worm-like Micelle / Redox reaction / Ferrocene / Vicoelasticity / Transmission Electron Microscopy / Molecular Assembly / Electrochemistry / レオロジー / cryo-TEM / 電気分解 / 酸化・還元 / サリチル酸ナトリウム |
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| Research Abstract |
A novel way of controlling fluid viscoelasticity using a "Faradaic (redox) reaction was studied. The system is based on a cationic redox-switchable ferrocenyl surfactant [(11-ferrocenylundecyl) trimethylammonium bromide, FTMA] that self-assembles into worm-like micelles in the presence of sodium salicylate (NaSal). The ferrocenyl group (reduced form) in the molecule is hydrophobic, while the ferricinium cation (oxidized form) acts as a hydrophilic moiety. This property gives remarkable change in the hydrophilic-lipophilic balance of FTMA, thereby changing its aggregation state.
An aqueous solution of mixed FTMA(reduced form) and NaSal exhibited a remarkable viscoelasticity. The viscoelastic behavior corresponded to a Maxwell-model and the zero shear viscosity was four orders of magnitude (15 Pass) higher that the viscosity of water (1x 10-3 Pass). Considerably elongated aggregates that are entangled with each other were observed on the FF-TEM micrograph. The high viscoelasticity observed for the mixed solution can therefore be ascribed to an entangled network of worm-like micelles.
This highly viscoelastic aqueous mixture was electrolyzed at +0.5 V vs. SCE. The viscosity of the system dramatically decreased and the elasticity disappeared after electric oxidation. The oxidized sample was a Newtoniam fluid and its viscosity had a value of 2.5x 10-3 Pass, which is about 1/6000 of the zero shear viscosity of the reduced sample. This remarkable viscoelasticity decrease is caused by a significant change in the aggregation state of FTMA and NaSal mixture from worm-like micelles to monomers and/or other smaller aggregates due to the enhanced hydrophilicity of FTMA. The method that we report are applicable to the controlled release of substances such as dyes and perfumes entrapped in an entangled network of worm-like micelles, ink for inkjet printers, flow rate controlling systems using electrical signals, clutches for transmission and valves.
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