Wiese Ettiene Hugo, Otto Daniel P, Smit Frans Johannes, Jordaan Johannes H L, Vosloo Hermanus Cornelius M
Research Focus Area for Chemical Resource Beneficiation, Catalysis and Synthesis Research Group, North-West University, 11 Hoffman Street, Potchefstroom 2522, South Africa.
Langmuir. 2025 Jan 28;41(3):1547-1555. doi: 10.1021/acs.langmuir.4c02687. Epub 2025 Jan 14.
This study investigates the surfactant properties and efficiency of linear and Guerbet-type amino acid surfactants. Utilizing a Wilhelmy plate method, we assessed the colloidal efficiency of these surfactants, with the lowest observed critical micelle concentration at 0.046 mmol L, significantly reducing surface tension to as low as 25.1 mN·m. Furthermore, the self-diffusion coefficients of the various surfactants have been determined through H pulsed-field gradient nuclear magnetic resonance diffusion-ordered spectroscopy. The self-diffusion coefficients are linked to the surface tension reduction as a function of concentration to determine the characteristic time scale of diffusion. In this work, the characteristic time scale of diffusion of a series of surfactants was calculated to investigate the interfacial coverage efficiency. Our findings indicate an inverse relationship between the characteristic time scale of diffusion and critical micelle concentrations across surfactants with hydrocarbon tail lengths of 8-22 carbons. Shorter tails correspond to lower colloidal efficiencies, but rapid surface tension reduction, resulting in the characteristic time scale of diffusion values ranging from 120 ns to 2.15 s. This property is crucial for applications requiring rapid action, such as enhancing aerosol efficiency, improving dispersion, and wetting materials in products.
本研究调查了线性和格尔伯特型氨基酸表面活性剂的表面活性剂性质及效率。利用威尔海姆平板法，我们评估了这些表面活性剂的胶体效率，观察到的最低临界胶束浓度为0.046 mmol/L，可将表面张力显著降低至低至25.1 mN·m。此外，通过H脉冲场梯度核磁共振扩散排序光谱法测定了各种表面活性剂的自扩散系数。自扩散系数与作为浓度函数的表面张力降低相关联，以确定扩散的特征时间尺度。在这项工作中，计算了一系列表面活性剂的扩散特征时间尺度，以研究界面覆盖效率。我们的研究结果表明，对于碳氢化合物尾链长度为8 - 22个碳的表面活性剂，扩散特征时间尺度与临界胶束浓度呈反比关系。较短的尾链对应较低的胶体效率，但表面张力降低迅速，导致扩散特征时间尺度值范围为120 ns至2.15 s。这一特性对于需要快速作用的应用至关重要，例如提高气雾剂效率、改善分散性以及使产品中的材料湿润。
