Quantum Chemical Study of the Carbon Dioxide-Philicity of Surfactants: Effects of Tail Functionalization
Quantum Chemical Study of the Carbon Dioxide-Philicity of Surfactants: Effects of Tail Functionalization
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表面活性剂二氧化碳亲和性的量子化学研究：尾部官能化的影响
DOI：
10.1021/acs.langmuir.0c02789
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发表时间：
2020
期刊：
影响因子：
3.9
通讯作者：
Wang Muhan
中科院分区：
文献类型：
--
作者：
Zhang Yingnan;Li Jiawei;Yin Zhipeng;Zhang Jun;Guo Wenyue;Wang Muhan
亲二氧化碳(CO2)表面活性剂在有机合成、压裂采油、聚合、萃取等领域具有广阔的应用前景，可用于提高超临界CO2(scCO(2))的粘度。本工作利用密度泛函理论从新的角度研究了表面活性剂尾部的官能团与亲二氧化碳性之间的关系。研究了三种常见的官能团类型（氟化基团、氧化基团和甲基基团）。结合能分析表明，所有三种类型的官能团都可以提高表面活性剂的亲二氧化碳性。在这三种官能团中，观察到氧化官能团与CO2分子的相互作用最强，其次是半氟化、氟化和甲基。然而，CO2分子倾向于吸附在氧化基团的中段，CO2分子的侵入导致氧化性表面活性剂的溶解度较低。相反，氟化基团和甲基基团在表面活性剂尾部末端与二氧化碳相互作用。因此，含氟表面活性剂在CO2中表现出最好的溶解度。因此，表面活性剂在CO2中的溶解度不仅与表面活性剂与CO2之间的相互作用强度有关，还取决于相互作用结构。本研究结果为评估表面活性剂CO2亲和性提供了新的策略，并为设计在scCO(2)中具有高溶解度的表面活性剂提供了指导。
Carbon dioxide (CO2)-philic surfactants have broad application prospects in organic synthesis, fracture-enhanced oil recovery, polymerization, extraction, and other fields and can be used to enhance the viscosity of supercritical CO2 (scCO(2)). In this work, the relationship between the functional group of the surfactant tail and CO2-philicity is studied from a new perspective using density functional theory. Three common functional group types (fluorinated, oxidative, and methyl groups) were investigated. The analysis of binding energy demonstrates that all three types of functional groups can improve the CO2-philicity of the surfactant. Among these three kinds of functional groups, the strongest interaction with CO2 molecules is observed for oxidative functional groups followed by semifluorinated, fluorinated, and methy groups. However, the CO2 molecules tend to be adsorbed onto the middle segment of the oxidative group, and the intrusion of the CO2 molecules results in the low solubility of oxidative surfactants. In contrast, fluorinated and methyl groups interact with CO2 at the end of the surfactant tail. As a result, the fluorinated surfactants show the best solubility in CO2 Therefore, the solubility of a surfactant in CO2 is not only related to the interaction strength between the surfactant and CO2, it also depends on the interaction structure. The results of this study provide a new strategy for evaluating surfactant CO2-philicity and provide guidance for the design of surfactants with high solubility in scCO(2).