Choline chloride/urea (1:2) is the most widely used deep eutectic solvent, which has attracted much attention due to its excellent advantages of low cost, environment friendly and easy synthesis. In this work, nanofriction-based molecular dynamics simulations were performed to investigate the effect of interfacial hydrophilicity on the flow resistance of Choline chloride/urea (1:2) confined in ionic model nanoslits. Simulation results showed that the flow resistance of the choline chloride/urea system increases with the increasing interfacial hydrophilicity. Urea molecules form a preferential adsorption layer on the wall. As the interfacial hydrophilicity increases, the number of urea molecules in the interfacial adsorption layer increased, whereas the stability decreased. Unique confined spatial distributions of urea molecules greatly contribute to ionic association between choline cations and chloride anions. Furthermore, with the increase of interfacial hydrophilicity, orientation distributions of urea molecules in the adsorption layer are more orderly, then causing a decrease in the average hydrogen bond number (N_HB) of urea molecules. Moreover, the more the N_HB of urea molecules, the better is the stability in the interfacial adsorption layer, which in turn results in less flow resistance.

氯化胆碱/脲（1：2）是使用最广泛的深共熔溶剂，由于其低成本，环境友好和易于合成的优异优势而备受关注。在这项工作中，进行了基于纳米摩擦的分子动力学模拟，以研究界面亲水性对局限在离子模型纳米缝隙中的氯化胆碱/脲（1：2）的流动阻力的影响。模拟结果表明，氯化胆碱/尿素体系的流动阻力随着界面亲水性的增加而增加。尿素分子在壁上形成优先吸附层。随着界面亲水性的增加，界面吸附层中脲分子的数量增加，而稳定性降低。尿素分子的独特局限性空间分布极大地促进了胆碱阳离子和氯离子之间的离子缔合。此外，随着界面亲水性的增加，吸附层中尿素分子的取向分布更加有序，从而导致平均氢键数减少（N _HB）的尿素分子。而且，尿素分子的N _HB越多，界面吸附层的稳定性越好，这反过来导致较小的流阻。