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[求助]
请好心人帮忙翻译一段话，非常感谢谢谢
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Changing solvent composition also affects the cmc’s;Small- and wide-angle X-ray scattering and small-angle neutron diffraction studies have shown that EAN’s nonpolar domains remain intact up to quite high water content. Therefore, it could be expected that the EAN/water mixtures would be capable of dissolving high concentrations of surfactant, like pure EAN. However, as water is added the volume fraction of the apolar region is lowered, reducing alkyl chain solubility. Neutron diffraction has also revealed strong hydrogen bonding between EAN and water, with each water molecule forming, on average, 1.5 hydrogen bonds with EAN in a 50/50 wt % EAN/water mixture. If these intersolvent hydrogen bonds form in preference to hydrogen bonds between the mixed solvent and the surfactant head group, this could further lower surfactant solubility. Both effects favor lower cmc’s. Similarly, ΔG°mic and ΔG°ads become more negative with increased water concentration, indicating that aggregation and adsorption are favored, in accordance with reduced surfactant solubility. Surfactant cmc’s are the highest, and ΔG° mic and ΔG° adsvalues the least negative, in the 75 wt %EAN/25 wt % H2O mixture. As the volume of the alkyl regions in this mixture is lower than for pure EAN, which will reduce surfactant solubility, incorporation of water into the charged domains must increase surfactant head group solubility. These two effects are competing, and as the water content is further increased the reduced hydrophobic volume dominates and cmc’s are reduced. |
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2楼2013-03-26 20:10:36
