Abstract:
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.
摘要:
近年来,人们对提供令人愉悦气味的日常化学产品越来越感兴趣。添加的香料分子可以诱导表面活性剂聚集体的微观结构转变,进一步影响产品的理化性质。这里,四种芳香醇(肉桂醇,苯基乙醇,研究了苯基甲醇和茴香醇)在十六烷基三甲基溴化铵(CTAB)/KBr聚集体上的作用。流变学的综合结果,动态光散射,透射电子显微镜测量表明,肉桂醇诱导了显著的胶束生长,而其他芳族醇的胶束生长增加不明显。水的界面摩尔浓度的变化,芳香醇,使用化学捕获方法研究了这种跃迁过程中的溴离子。添加肉桂醇引起的转变伴随着界面水和溴离子摩尔浓度的显着下降,界面醇摩尔浓度上升。在先前对辛醇诱导的蠕虫状胶束和囊泡形成的研究中未观察到界面水摩尔浓度的显着降低,这表明当前系统中存在不同的机制。核磁共振研究表明,肉桂醇之间的π-π堆积,但不是醇和CTAB头基之间的阳离子-π相互作用,促进了CTAB聚集体中醇分子的紧密堆积,并从界面区域排斥水。目前的研究可能为添加剂存在下表面活性剂聚集体的形态调控提供理论依据。