Department of Chemical and Pharmaceutical Engineering, Faculty of Chemistry and Pharmacy , Sofia University , 1 James Bourchier Boulevard , Sofia 1164 , Bulgaria.
Faculty of Biotechnology and Food Engineering , Technion-Israel Institute of Technology , Haifa 3200000 , Israel.
Langmuir. 2018 Apr 24;34(16):4897-4907. doi: 10.1021/acs.langmuir.8b00421. Epub 2018 Apr 13.
Here, we have investigated the synergistic growth of long wormlike micelles and their transformation into disklike micelles, which occurs in three-component solutions composed of sodium lauryl ether sulfate (SLES; anionic), cocamidopropyl betaine (CAPB; zwitterionic), and dodecanoic acid (HC12; nonionic). The solution rheology is characterized in terms of zero-shear viscosities and characteristic times for micellar breaking and reptation. Furthermore, the microstructure evolution, leading to the observed rheological behavior, is revealed by cryo-transmission electron microscopy (TEM) micrographs. In all cases, the CAPB-to-SLES ratio is fixed, whereas the fatty acid concentration is varied. At a certain HC12 concentration, the solution viscosity passes through a maximum. The cryo-TEM imaging indicates that wormlike micelles appear before the peak, grow further up to the peak, and finally transform into disklike aggregates (a very rare micellar structure) after the peak. The transformation of worms into disks leads to a drop in viscosity because the length-to-thickness aspect ratio of the disks is significantly lower than that of the worms. In this article, we elucidate the structure-rheology relations in micellar solutions that might be applied for the design of personal-care and household formulations.
在这里，我们研究了长蠕虫状胶束的协同生长及其在由硫酸月桂醚（阴离子）、椰油酰胺丙基甜菜碱（两性离子）和十二烷酸（非离子）组成的三元溶液中向盘状胶束的转变。通过零剪切粘度和胶束破裂和蠕动的特征时间来描述溶液流变性。此外，通过低温透射电子显微镜（TEM）照片揭示了导致观察到的流变行为的微观结构演变。在所有情况下，固定椰油酰胺丙基甜菜碱与硫酸月桂醚的比例，而改变脂肪酸的浓度。在一定的十二烷酸浓度下，溶液粘度通过最大值。低温 TEM 成像表明，在出现峰值之前出现蠕虫状胶束，在峰值之前进一步生长，并且在峰值之后最终转变成盘状聚集体（一种非常罕见的胶束结构）。蠕虫向盘的转变导致粘度下降，因为盘的长度与厚度的纵横比明显低于蠕虫的纵横比。在本文中，我们阐明了可能应用于个人护理和家庭制剂设计的胶束溶液中的结构流变关系。
