十二烷基硫酸钠水溶液表面张力的温度依赖性
Temperature dependence of surface tension in aqueous sodium dodecyl sulfate solutions
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中文总结 AI 辅助
本研究测量了SDS水溶液在不同浓度和温度下的表面张力，发现温度系数在低浓度时变号，且与cmc无关，归因于表面活性剂层变薄，可通过浓度调控热毛细应力。
中文摘要 AI 辅助
我们采用Wilhelmy板法，在0.17至43 mM的十六个浓度（涵盖室温临界胶束浓度（cmc）的0.02至5倍）以及26至83摄氏度的温度范围内，报告了十二烷基硫酸钠水溶液的表面张力测量结果。在最低浓度下，表面张力随温度降低而减小，这与纯水的情况一致。然而，在约0.4 mM以上，表面张力随温度升高而增大：温度系数在0.3至0.8 mM（约为cmc的十分之一）的浓度范围内改变符号，并在接近3 mM时达到+0.53 mN m⁻¹ K⁻¹，其大小为纯水的三倍且符号相反。在cmc以上，表面张力几乎与温度无关，饱和于35.2±0.3 mN m⁻¹。该行为不能归因于cmc的温度依赖性，因为后者弱了一个数量级。相反，这与表面活性剂层随温度升高而变薄的现象一致。结果表明，SDS溶液中热毛细应力的符号和大小可通过浓度进行选择。
英文摘要
We report measurements of the surface tension of aqueous sodium dodecyl sulfate solutions at sixteen concentrations from 0.17 to 43$\,$mM, spanning 0.02 to 5 times the room-temperature critical micelle concentration (cmc), and at temperatures from 26 to 83$\,$$^\circ{\rm C}$, using the Wilhelmy plate method. At the lowest concentration the surface tension decreases with temperature, as it does for pure water. Above about 0.4$\,$mM, however, it increases: the temperature coefficient changes sign at a concentration of 0.3 to 0.8$\,$mM, roughly a tenth of the cmc, and reaches $+0.53\,\rm mN\,m^{-1}\,K^{-1}$ near 3$\,$mM, three times the magnitude of that of pure water and of the opposite sign. Above the cmc the surface tension is nearly independent of temperature, saturating at $35.2\pm0.3\,\rm mN\,m^{-1}$. The behavior cannot be attributed to the temperature dependence of the cmc, which is an order of magnitude too weak. It is instead consistent with a surfactant layer that thins as the temperature rises. The results imply that the sign and magnitude of thermocapillary stresses in SDS solutions can be selected through the concentration.
发表机构
- Konkuk University（建国大学）
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