Ion specific effects in trivalent counterion induced surface and solution self-assembly of the anionic surfactant sodium polyethylene glycol monododecyl ether sulfate.
Ion specific effects in trivalent counterion induced surface and solution self-assembly of the anionic surfactant sodium polyethylene glycol monododecyl ether sulfate.
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DOI：
10.1021/la500937g
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发表时间：
2014-04
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通讯作者：
Hui Xu;J. Penfold;R. Thomas;J. Petkov;I. Tucker;J. Webster;I. Grillo;Alvin V. Terry
中科院分区：
文献类型：
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作者：
Hui Xu;J. Penfold;R. Thomas;J. Petkov;I. Tucker;J. Webster;I. Grillo;Alvin V. Terry
用中子反射法和小角中子散射法研究了Al（3+）、Cr（3+）、Sc（3+）、Gd（3+）和La（3+）对阴离子表面活性剂聚乙二醇单十二烷基醚硫酸钠表面吸附及Al（3+）、Cr（3+）和Sc（3+）溶液自组装的影响。三价反离子与阴离子表面活性剂之间的强结合和络合导致在相对低的反离子浓度下在空气-水界面处显著的胶束生长和表面多层结构的形成。广泛相似的表面和溶液行为观察到不同的三价抗衡离子。表面和溶液结构的演变详细地取决于反离子的性质，其水合半径和结合强度。例外地，Cr（3+）抗衡离子的加入具有不太明显的效果。这是由于在初级水合壳层内对Cr（3+）离子的交换具有更大的阻力，这导致静电相互作用的屏蔽和减少的表面电荷-电荷结合。
The effect of different trivalent counterions, Al(3+), Cr(3+), Sc(3+), Gd(3+), and La(3+), on the surface adsorption and Al(3+), Cr(3+), and Sc(3+) for solution self-assembly of the anionic surfactant sodium polyethylene glycol monododecyl ether sulfate has been studied by neutron reflectivity and small angle neutron scattering. The strong binding and complexation between the trivalent counterions and the anionic surfactant result in significant micellar growth and the formation of surface multilayer structures at the air-water interface at relatively low counterion concentrations. Broadly similar surface and solution behaviors are observed for the different trivalent counterions. The evolution in the surface and solution structures in detail depends upon the nature of the counterion, its hydrated radius and its strength of binding. Exceptionally the addition of Cr(3+) counterions have a less pronounced effect. This is attributed to a greater reluctance for exchange within the primary hydration shell for Cr(3+) ions, which results in a shielding of the electrostatic interactions and a reduced surfactant-counterion binding.