Effect and mixing of counter anions at the surface of aqueous solution of imidazolium-based ionic liquids
Effect and mixing of counter anions at the surface of aqueous solution of imidazolium-based ionic liquids
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DOI：
10.1016/j.colsurfa.2013.02.062
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发表时间：
2013-06
期刊：
影响因子：
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通讯作者：
Huihui Li;Y. Imai;T. Takiue;H. Matsubara;M. Aratono
中科院分区：
文献类型：
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作者：
Huihui Li;Y. Imai;T. Takiue;H. Matsubara;M. Aratono
本研究的目的是找出决定1-烷基-3-甲基咪唑离子液体（IL, CnmimX）在空气/水界面上的反阴离子混合的主要因素。首先，通过对c10mimbr - c10mimbf4混合物表面张力数据的热力学分析，估计了其吸附膜的性能。与c6mimbr - c6mimbf4混合物相比，吸附膜中BF4−的摩尔分数低于理想状态，过量吸附能为负。同时，在c6mimbr - c6mimbf4体系中，在吸附膜上形成BF4−和咪唑环并排离子对的可能性大大降低。这些变化主要是由于BF4−与C10mim+之间的氢键相互作用减少，Cnmim+疏水部分的碳数从6增加到10。此外，发现c10mimbr - c10mimbf4体系的过量吸附能小于十二烷基三甲基铵（C12TA） br - c12tabf4体系，后者仅存在对抗阴离子和表面活性剂阳离子之间的远程哥伦比亚相互作用。因此，我们得出结论，短程氢键相互作用在il的界面活性中起重要作用。
The purpose of this study was to find the primary factor determining the mixing of the counter anions of 1-alkyl-3-methylimidazolium-based ionic liquid (IL, CnmimX) at the air/water interface. First, the properties of the adsorbed films of the C10mimBr–C10mimBF4mixtures were estimated by using the thermodynamic analysis of their surface tension data. The mole fraction of BF4−was lower in the adsorbed films than in the ideal state and the excess Gibbs energy of adsorption was negative, which was in marked contrast to those of the C6mimBr–C6mimBF4mixtures. Meanwhile, the possibility of forming side-by-side ion pair of BF4−and imidazolium ring at the adsorbed films, as we found in the C6mimBr–C6mimBF4system, was greatly reduced in the present case. These changes were mainly attributed to the reduction in the hydrogen-bonding interaction between BF4−and C10mim+, as the carbon number in the hydrophobic part of Cnmim+was increased from 6 to 10. In addition, it was found that the values of excess Gibbs energy of adsorption were less negative in the C10mimBr–C10mimBF4system than in the dodecyltrimethylammonium (C12TA)Br–C12TABF4system, where the long-range Columbic interaction solely exists between the counter anions and surfactant cations. Thus, we concluded that the short-range hydrogen-bonding interaction played an essential role in the interfacial activity of ILs.