Department of Daily Chemical Engineering, Beijing Technology and Business University, No. 11 Fucheng Road, Beijing 100048, China.
McIntire School of Commerce, University of Virginia, Charlottesville, VA 22903, USA.
Molecules. 2022 Jul 6;27(14):4333. doi: 10.3390/molecules27144333.
In recent years, there has been increasing interest in daily-use chemical products providing a pleasant scent. The added fragrance molecules may induce microstructural transitions of surfactant aggregates, which further affect the physical and chemical properties of the products. Here, the effects of four types of aromatic alcohols (cinnamyl alcohol, phenyl ethanol, phenyl methanol and anisyl alcohol) on cetyltrimethylammonium bromide (CTAB)/KBr aggregates were studied. The combined results from rheology, dynamic light scattering, and transmission electron microscopy measurements showed that cinnamyl alcohol induced significant micellar growth, while increases in micellar growth were less obvious for the other aromatic alcohols. The changes in the interfacial molarities of water, aromatic alcohol, and bromide ions during such transitions were studied using the chemical trapping method. Transitions resulting from added cinnamyl alcohol were accompanied by significant declines in interfacial water and bromide ion molarities, and a rise in interfacial alcohol molarity. The marked decrease in interfacial water molarity was not observed in previous studies of the octanol induced formation of wormlike micelles and vesicles, indicating that a different mechanism was presented in the current system. Nuclear magnetic resonance investigation showed that π-π stacking between cinnamyl alcohols, but not cation-π interactions between alcohols and CTAB headgroups, facilitated the tight packing of alcohol molecules in CTAB aggregates and the repulsion of water from the interfacial region. The current study may provide a theoretical basis for the morphological regulation of surfactant aggregates in the presence of additives.
近年来，人们对提供宜人香味的日常使用化学品越来越感兴趣。添加的香味分子可能会诱导表面活性剂聚集体的微结构转变，这进一步影响产品的物理和化学性质。在这里，研究了四种芳香醇（肉桂醇、苯乙醇、苯甲醇和茴香醇）对十六烷基三甲基溴化铵（CTAB）/KBr 聚集体的影响。流变学、动态光散射和透射电子显微镜测量的综合结果表明，肉桂醇诱导了显著的胶束生长，而其他芳香醇的胶束生长增加不明显。使用化学捕获法研究了这些转变过程中界面水、芳香醇和溴化物离子的界面摩尔浓度的变化。加入肉桂醇引起的转变伴随着界面水和溴化物离子摩尔浓度的显著下降，以及界面醇摩尔浓度的上升。在先前关于辛醇诱导形成蠕虫状胶束和囊泡的研究中，没有观察到界面水摩尔浓度的明显下降，这表明当前体系中呈现出不同的机制。核磁共振研究表明，肉桂醇之间的π-π堆积，而不是醇和 CTAB 头基之间的阳离子-π相互作用，促进了醇分子在 CTAB 聚集体中的紧密堆积，并排斥水进入界面区域。本研究可为添加剂存在下表面活性剂聚集体的形态调节提供理论依据。
