Ionic liquid (IL)/polyimide (PI) composite membranes demonstrate promise for use in CO₂ separation applications. However, few studies have focused on the microscopic mechanism of CO₂ in these composite systems, which is important information for designing new membranes. In this work, a series of systems of CO₂ in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide composited with 4,4-(hexafluoroisopropylidene) diphthalic anhydride (6FDA)-based PI, 6FDA-2,3,5,6-tetramethyl-1,4-phenylene-diamine, at different IL concentrations were investigated by all-atom molecular dynamics simulation. The formation of IL regions in PI was found, and the IL regions gradually became continuous channels with increasing IL concentrations. The analysis of the radial distribution functions and hydrogen bond numbers demonstrated that PI had a stronger interaction with cations than anions. However, the hydrogen bonds among PI chains were destroyed by the addition of IL, which was favorable for transporting CO₂. Furthermore, the self-diffusion coefficient and free energy barrier suggested that the diffusion coefficient of CO₂ decreased with increasing IL concentrations up to 35 wt-% due to the decrease of the fractional free volume of the composite membrane. However, the CO₂ self-diffusion coefficients increased when the IL contents were higher than 35 wt-%, which was attributed to the formation of continuous IL domain that benefitted the transportation of CO₂.

离子液体（IL）/聚酰亚胺（PI）复合膜具有在CO ₂分离应用中使用的前景。然而，很少有研究集中在这些复合系统中CO ₂的微观机理上，这对于设计新膜是重要的信息。在这项工作中，一系列的CO ₂系统与基于4,4-（六氟异亚丙基）二邻苯二甲酸酐（6FDA）的PI，6FDA-2,3,5,6-四甲基-1,4-亚苯基二胺复合的1-丁基-3-甲基咪唑鎓双（三氟甲基磺酰基）酰亚胺通过全原子分子动力学模拟研究了在不同IL浓度下的，。发现在PI中IL区域的形成，并且随着IL浓度的增加，IL区域逐渐变成连续的通道。对径向分布函数和氢键数的分析表明，PI与阴离子的相互作用强于阴离子。然而，通过添加IL破坏了PI链之间的氢键，这对于运输CO ₂是有利的。此外，自扩散系数和自由能垒表明CO的扩散系数由于复合膜的自由体积分数的减少，当IL浓度增加至35 wt％时，₂降低。然而，当IL含量高于35wt％时，CO ₂自扩散系数增加，这归因于形成了连续的IL结构域，这有利于CO ₂的运输。