表面活性剂对CO_2中表面润湿的分子动力学模拟

Molecular dynamics simulation of effects of surfactant on surface wettability in CO_2 environment

通过分子模拟方法,研究稠密CO2溶剂中,全氟聚醚表面活性剂对水在3种不同亲水表面的润湿性的影响。结果表明:对于疏水性表面,表面活性剂部分取代存在于水滴和表面之间的CO2分子;对于弱亲水性表面,表面活性剂的加入使得水滴基本脱离表面;而在强亲水表面上,表面活性剂的加入增大水滴的接触角,减弱表面润湿性。同时进一步分析表面活性剂在水/CO2界面处的密度分布。总之,在稠密CO2溶剂中,表面活性剂能够改善表面的润湿性,这将有利于表面上亲水物质的脱除。

In the present of CO2 fluid, molecular dynamics simulations were performed to investigate the effects of perfluoropolyether ammonium carboxylate surfactant （Cll F23 04 COO- NH4 ） on the wetting be- havior of solid surfaces. The obtained liquid/vapor contact line indicated that the surfactant could partial- ly replace the interfacial CO2 molecules, which resided in the solid/liquid interfacial region on hydropho- bic surface. For a weak hydrophilic surface, the addition of surfactant almost made the droplet lose con- tact with the surface, while on a strong hydrophilic surface, the surfactants enhanced the droplet contact angle and weakened the surface wettability. The height of the center of mass of the droplet, as a function of simulation time, further showed the wetting behavior of the water droplet. The component distributions of surfactant could be seen in the density profiles of water, and surfactant headgro demonstrated that the surfactant could well improve the wettability of the surface in was in favor of the removal of the hydrophilic substance. up and tail. It was dense C02, thus it