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阐述了用分子动力学(molecular dynamics,MD)模拟方法研究在T=303K条件下〔mmim〕〔TFSA〕、〔emim〕〔TFSA〕、〔bmim〕〔TFSA〕、〔C6mim〕〔TFSA〕和〔C8mim〕〔TFSA〕5种离子液体的输运特性。模拟力场采用修正后的OPLS力场。根据模拟轨迹计算得到5种离子液体的密度值。根据均方位移(MSD)的斜率计算得到的离子液体阴阳离子自扩散系数。采用Nernst-Einstein(NE)方程计算得到离子液体摩尔导电率。这些模拟结果与实验值很吻合。离子液体的自扩散系数和电导率随着阳离子链长的增长而变小,主要原因是阳离子链长增长使离子液体中的氢键作用和范德华作用变强。计算所得离子液体摩尔导电率略大于实验测量值则归因于离子关联运动的结果。
The effects of [mmim] [TFSA], [emim] [TFSA], [bmim] [TFSA], [C6mim] [TFSA] and [ C8mim〕 〔TFSA〕 5 kinds of ionic liquid transport characteristics. The simulated force field uses the modified OPLS force field. Calculated according to the simulated trajectory of five kinds of ionic liquid density. Calculate the self-diffusion coefficient of anion and cation of ionic liquid according to the slope of mean square displacement (MSD). The ionic liquid molar conductivity was calculated using the Nernst-Einstein (NE) equation. These simulation results are in good agreement with the experimental data. The self-diffusion coefficient and conductivity of ionic liquids decrease with the increase of cationic chain length, which is mainly due to the hydrogen bond and van der Waals interactions in ionic liquids. Calculating the ionic conductivity of the resulting ionic liquid slightly larger than the experimental measurement is attributed to the results of ion-dependent motions.