Interfacial vs Bulk Phenomena Effects on the Surface Tensions of Aqueous Magnetic Surfactants in Uniform Magnetic Fields
Interfacial vs Bulk Phenomena Effects on the Surface Tensions of Aqueous Magnetic Surfactants in Uniform Magnetic Fields
复制标题
均匀磁场中界面与本体现象对水性磁性表面活性剂表面张力的影响
DOI：
10.1021/acs.langmuir.0c01215
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发表时间：
2020
期刊：
影响因子：
3.9
通讯作者：
Scovazzo, Paul
中科院分区：
文献类型：
--
作者：
Reed, Derek M.;Fortenberry, Alex;Wolfe, Emily A.;Stanhope, Rachel A.;Daniel, Carla I.;Hern, Caleb M.;Smith, Adam E.;Scovazzo, Paul
文献清楚地报道了磁性表面活性剂系统对磁场的响应。该手稿调查，如果响应是因为磁场直接改变的界面性质，或者如果表面活性的性质是独立的顺磁性流体的响应。它使用均匀和梯度磁场来确定离子磁性表面活性剂的磁致表面张力的变化，而不受本体顺磁流体效应的影响。磁诱导的表面张力的降低是小的相比，大量的顺磁流体的影响。报告的表面张力下降明显小于之前文献中发现的结果，后者报告了界面和体顺磁效应的结合。磁致表面张力变化是磁性部分与表面活性剂的两亲性结构的缔合度α的函数。因此，对这个问题的建议答案是，当α接近零时，磁性表面活性剂系统的磁性接近普通顺磁流体的行为。对于α接近1的磁性表面活性剂，存在可测量的界面响应。例如，在这项研究中，与α =不可检测的磁性表面活性剂相比，α = 0.92的磁性表面活性剂具有2.5倍的磁致表面张力变化，即使它们具有相似的磁矩。
The literature clearly reports that magnetic surfactant systems respond to magnetic fields. This manuscript investigates if the responses are because the magnetic fields directly alter the interfacial properties or if the surface-active properties are independent of the paramagnetic fluid responses. It uses uniform and gradient magnetic fields to determine the magnetically induced changes to the surface tensions independent of bulk paramagnetic fluid effects for ionic magnetic surfactants. The magnetically induced decrease in surface tensions is small compared to the bulk paramagnetic fluid effects. The reported decrease in surface tensions is significantly smaller than those previously found in the literature, which reported a combined interfacial and bulk paramagnetic effect. The magnetically induced surface tension changes are a function of the degree of association, α, of the magnetic moiety with the surfactant’s amphiphilic structure. Therefore, the proposed answer to the question is that as α approaches zero, the magnetic properties of the magnetic surfactant system approaches the behavior of an ordinary paramagnetic fluid. For magnetic surfactants with α approaching one, there is a measurable interfacial response. For example in this study, a magnetic surfactant with α = 0.92 had a 2.5 times greater magnetically induced change in surface tension compared to a magnetic surfactant with α = undetectable, even thought they had similar magnetic moments.