College of Science and ‡Key Laboratory of New Energy Physics & Materials Science in Universities of Shandong, China University of Petroleum , 266580 Qingdao, Shandong, China.
Langmuir. 2017 May 30;33(21):5291-5297. doi: 10.1021/acs.langmuir.7b01176. Epub 2017 May 15.
Forming wormlike reverse micelles (RMs) by hydrocarbon surfactant self-assembly is an economic and environmental strategy to improve the physicochemical properties of supercritical carbon dioxide (scCO), but it remains challenging. Introducing cosurfactant in hydrocarbon surfactant self-assembly system is a potential method to generate wormlike RMs. Here, adopting molecular dynamics simulations, we performed hydrocarbon surfactant (TC14) self-assembly with introducing cosurfactants (CBenz). It is found that adding the CBenz molecules will induce the spherical RMs to a short rodlike form. In this case, the microstructure of the short rodlike RMs shows a dumbbell-like form that is composed by three parts including a middle part of CBenz and two parts of TC14 aggregation at both ends of rodlike RMs, which is regarded as the origin of RMs shape transition. Further, the analysis of free energy for RMs fusion indicates that the high fusion ability of CBenz aggregation drives the formation of the dumbbell-like RMs. Accordingly, enhancing the affinity of the CBenz is found to be effective strategy to further fusion of rodlike RMs in end-to-end manner, yielding a wormlike RMs with a beads-on-a-string structure. It is expected that this work will provide a valuable information for design the hydrocarbon wormlike RMs and facilitate the potential application of scCO.
通过烃基表面活性剂自组装形成蠕虫状反胶束（RMs）是一种提高超临界二氧化碳（scCO）物理化学性质的经济环保策略，但仍具有挑战性。在烃基表面活性剂自组装体系中引入助表面活性剂是生成蠕虫状 RMs 的一种潜在方法。在这里，我们采用分子动力学模拟，在烃基表面活性剂（TC14）自组装中引入助表面活性剂（CBenz）。结果发现，添加 CBenz 分子会诱导球形 RMs 转变为短棒状。在这种情况下，短棒状 RMs 的微观结构呈现出哑铃状，由中间的 CBenz 部分和两端的 TC14 聚集部分组成，这被认为是 RMs 形状转变的起源。此外，对 RMs 融合自由能的分析表明，CBenz 聚集的高融合能力驱动了哑铃状 RMs 的形成。因此，提高 CBenz 的亲合力被发现是进一步以端到端方式融合棒状 RMs、形成串珠状蠕虫状 RMs 的有效策略。预计这项工作将为设计烃基蠕虫状 RMs 提供有价值的信息，并促进 scCO 的潜在应用。
