As a kind of green solvent, supercritical CO2 microemulsion is the polar microaggregate formed in nonpolar continual phase and it widens the application scope of supercritical CO2. The properties of microemulsion are closely related to its constituents and structure, it is necessary to further study the microstructure of its aggregate. The paper carried out a molecular dynamics simulation research for the Ls-36 supercritical CO2 microemulsion systems respectively formed by three kinds of ionic liquids including [bmim][PF6], [bmim][BF4] and [bmim][Ac], the results show that all these three kinds of ionic liquids can form stable microemulsion and their microemulsion structures are similar. Due to the effect of anion structure of ionic liquid, there are apparent differences of the stretching angle of Ls-36 tail chains in CO2. For [bmim][Ac] system, Ls-36 tail chain more approximates the normal direction of the outer surface of agglomerate, the scope of the included angle formed with the normal direction of the outer surface of agglomerate is 30°～70°, the radius of microemulsion is also the largest and it is 3.12 nm; for [bmim][PF6] system, the scope of the included angle formed between Ls-36 tail chain and the normal direction is 78°～125°, the radius of microemulsion is 2.88 nm; for [bmim][BF4] system, Ls-36 tail chain stretches more approximate to the side of agglomerate, the scope of the included angle formed with the normal direction is 107°～150°, the radius of microemulsion is the smallest and it is 2.75nm. Under the conditions of same concentration of surfactant, water content, temperature and pressure, the emulsion agglomeration speed of [bmim][Ac] system is the fastest and the system is more stable. In addition, the ability of capturing polar water molecule is the most powerful and can reach 93.75％.%微乳液的性质与组成和结构密切相关,需要深入认识其聚集体的微观结构.对[bmim][PF6]、[bmim][BF4]、[bmim][Ac]这3种离子液体分别构建的Ls-36型超临界CO2微乳液体系进行了分子动力学模拟研究,结果表明均可以形成稳定的微乳液,且微乳液结构类似.Ls-36尾链在CO2中的伸展角度受离子液体阴离子结构的影响而有显著不同,[bmim][Ac]体系Ls-36尾链更靠近聚团外表面法线方向,相对于聚团外表面法线夹角范围为30°～70°,微乳液半径值也最大,为3.12 nm.[bmim][PF6]体系Ls-36尾链相对于法线夹角范围为78°～125°,微乳液半径为2.88 nm.[bmim][BF4]体系Ls-36尾链更贴近聚团一侧伸展,相对于法线夹角范围为107°～150°,微乳液半径值最小,为2.75 nm.相同表面活性剂浓度、含水量、温度及压力条件下,[bmim][Ac]体系聚乳速度最快、体系更稳定,同时对极性水分子的捕获能力最强,可达93.75％.
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