Interfacial behavior of gemini surfactants with different spacer lengths in aqueous medium
Interfacial behavior of gemini surfactants with different spacer lengths in aqueous medium
复制标题
不同间隔基长度的Gemini表面活性剂在水介质中的界面行为
DOI：
10.1007/s00396-018-4459-8
复制
发表时间：
2019
影响因子：
2.4
通讯作者：
Shibata Osamu
中科院分区：
文献类型：
--
作者：
Nakahara Hiromichi;Nishino Ayami;Tanaka Ayaka;Fujita Yoshika;Shibata Osamu
一系列烷二基-1-s-双（二甲基十四烷基溴化铵）（简称14-s-14，2Br−）在288.2、298.2和308.2 K的温度下在水介质中进行了表征。表面活性剂的临界胶束浓度（cmc）通过测量作为浓度的函数的表面张力和电导率来确定。通过电导率的测定，对胶束的形成进行了理论解释。采用稳态荧光猝灭法和动态光散射法分别测定了胶束的聚集数和粒径。此外，测量表面电位（ΔV）与表面活性剂浓度的关系，以了解位于空气-水界面的吸附层的冷凝状态。Δ V值可以直接捕捉到体块上方的表面区域中电荷的垂直不均匀移动，其中Δ V值为零或保持电中性。Δ V的测量结果表明，表面区域的吸附表面活性剂在远低于cmc的量方面是饱和的，并且14-s-14，2Br−的十四烷基链的垂直取向通过较长的间隔基以朝向空气的弯曲构象而得到改善。
A series of alkanediyl-1-s-bis(dimethyltetradecylammonium bromide) (abbr. 14-s-14,2Br−) has been characterized in an aqueous medium at temperatures of 288.2, 298.2, and 308.2 K. Critical micelle concentration (cmc) of the surfactants was determined by measuring the surface tension and electrical conductivity as a function of concentrations. The micelle formation was elucidated thermodynamically from the results of electrical conductivity measurement. A steady-state fluorescence quenching and dynamic light scattering were performed to determine the aggregation number and the size of micelles, respectively. Furthermore, the surface potential (ΔV) was measured against surfactant concentrations to understand the condensing state of the adsorbed layer located at the air–water interface. The ΔVvalue directly can catch a vertical unequal shift of electric charges in the surface region above the bulk where the ΔVvalue is zero or electroneutrality is held. The results of ΔVmeasurements indicated that the adsorbed surfactants in the surface region were saturated in terms of amounts far below the cmc and that the vertical orientation of tetradecyl chains of 14-s-14,2Br−was improved by the longer spacers in a bending conformation towards the air.