Phase Separation of Ternary Self-Assembled Monolayers into Hydrophobic 1-Dodecanethiol Domains and Electrostatically Stabilized Hydrophilic Domains Composed of 2-Aminoethanethiol and 2-Mercaptoethanesulfonic Acid on Au(111)
| Autor: | Daisuke Hobara, Yosuke Ooi, Masahiro Yamamoto, Naoya Nishi, Pham Hong Phong, Takashi Kakiuchi |
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| Rok vydání: | 2005 |
| Předmět: |
chemistry.chemical_classification
animal structures Analytical chemistry Self-assembled monolayer Surfaces and Interfaces Sulfonic acid Condensed Matter Physics Mole fraction chemistry.chemical_compound Crystallography Sulfonate chemistry Desorption Monolayer Electrochemistry General Materials Science Self-assembly Ternary operation Spectroscopy |
| Zdroj: | Langmuir. 21:10581-10586 |
| ISSN: | 1520-5827 0743-7463 |
| Popis: | Ternary self-assembled monolayers (SAM) composed of 2-aminoethanethiol (AET), 2-mercaptoethanesulfonic acid (MES), and 1-dodecanethiol (DDeT) form two types of domains as if it were a two-component SAM: DDeT-rich hydrophobic domains and electrostatically stabilized hydrophilic domains composed of MES and AET on Au(111). MES and AET behave virtually as a single surface-active species. Two distinct reductive desorption peaks in cyclic voltammograms (CV) and binarized images of scanning tunneling microscopy clearly show nanometer scale, yet macroscopically distinguishable, phase separation over a wide range of the mixing ratio of DDeT and MES-AET in the bathing solution. X-ray photoelectron spectroscopy measurements indicate that the ratio of MES to AET in the hydrophilic domains is unity and that both terminal groups are in the charged states, that is, the sulfonate group and the ammonium group. With decreasing the total concentration of the thiols, the mole fraction of DDeT in the bathing solution at which the surface coverage of MES-AET domains is equal to that of DDeT domains dramatically decreases. This suggests that the adsorption kinetics plays a crucial role in the formation of the domains structure. |
| Databáze: | OpenAIRE |
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