Effect of the Headgroup Structure on Counterion Binding in Adsorbed Surfactant Films Investigated by Total Reflection X-ray Absorption Fine Structure Spectroscopy
Effect of the Headgroup Structure on Counterion Binding in Adsorbed Surfactant Films Investigated by Total Reflection X-ray Absorption Fine Structure Spectroscopy
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DOI：
10.1246/bcsj.20180167
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发表时间：
2018-07
影响因子：
4
通讯作者：
Y. Imai;Y. Tokiwa;Shusaku Ueno;H. Tanida;I. Watanabe;H. Matsubara;T. Takiue;M. Aratono
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文献类型：
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作者：
Y. Imai;Y. Tokiwa;Shusaku Ueno;H. Tanida;I. Watanabe;H. Matsubara;T. Takiue;M. Aratono
用全反射X射线吸收精细结构（XAFS）谱研究了二元混合反离子与表面活性剂吸附膜头基的竞争结合。溴离子反离子的扩展XAFS χ谱是完全水合溴离子（游离Br）和部分脱水溴离子与表面活性剂离子的头基结合（结合Br）的谱的线性组合。根据反离子混合体系中结合Br的分数，提出了三甲基铵（TA+）和3-甲基咪唑（MIM+）头基的反离子结合相对强度的两个系列：（a）TA-SO_4 < TA-Cl < TA-Br <TA-BF_4和（B）MIM-Br < TA-Br <TA-BF_4 <MIM-BF_4。对于TA头基，根据柯林斯定律，匹配头基和抗衡离子的水合作用得到系列（a），该定律指出，当离子的水合能力的绝对值匹配时，接触离子对形成的趋势变得更大。对于MIM hea.
Competitive binding of binary mixed counterions to the headgroups of adsorbed surfactant films has been investigated at solution surfaces by total reflection X-ray absorption fine structure (XAFS) spectroscopy. The obtained extended XAFS χ spectra for bromide counterions are linear combinations of the spectra of fully hydrated bromide ions (free Br) and partially dehydrated bromide ions bound to the headgroups of the surfactant ions (bound Br). From the fraction of bound Br in counterion mixed systems, two series of the relative strengths of counterion binding are proposed for the trimethylammonium (TA+) and 3-methylimidazolium (MIM+) headgroups: (a) TA–SO4 < TA–Cl < TA–Br < TA–BF4 and (b) MIM–Br < TA–Br < TA–BF4 < MIM–BF4. For the TA headgroup, matching the hydration of the headgroups and counterions gives series (a) according to Collins’ law, which states that the tendency of contact ion pair formation becomes larger when the absolute values of the hydration enthalpies of the ions match. For the MIM hea...