【作者】 杨文泓； 杨小震；

【Author】 Wenhong Yang,Xiaozhen Yang Beijing National Laboratory for Molecular Sciences,Joint Laboratory of Polymer Science and Materials,State Key Laboratory of Polymer Physics and Chemistry,Institute of Chemistry,Chinese Academy of Sciences, Beijing 100190,China

【机构】 中国科学院化学研究所高分子物理与化学国家重点实验室；

【摘要】 通过MD方法模拟表面活性剂在气液界面的薄膜体系的破裂情况来预测表面活性剂用于稳定泡沫的能力,并将所得结果与实验进行对照。泡沫的稳定性从本质上就是由超薄膜的稳定性所决定的。我们将薄膜刚好不破的厚度定义为体系的临界膜厚,并以此来衡量薄膜体系的稳定性。同时考查了模拟时间与格子大小对临界膜厚的影响,得出在本研究中,模拟中微观尺度的结果可以与实验上宏观尺度的结果相比较。表面活性剂可以提高泡沫的稳定性,也就是会降低薄膜体系的临界膜厚,通过比较水/表面活性剂薄膜体系的临界膜厚与纯水体系的临界膜厚的降低程度,可以得出三种表面活性剂用于稳定薄膜体系的能力依SDS>LAS>C₁₂E₇次序逐渐降低。这与实验上泡沫的产生与半衰期的结果趋势一致。通过分析表面活性剂在气液界面的密度分布发现,各表面活性剂疏水端突出在水面部分的积分面积对表面活性剂稳定薄膜的能力有贡献,关系为突出的部分越少则所得薄膜的稳定性越强。更多还原

【Abstract】 MD simulation has been performed on water/surfactant film rupture in order to investigate foam stability.A periodic boundary film model which was simulated in a lateral dimension of 8×8 nm~2 for 4 ns was established to stand for a part of a foam bubble.Based on critical film thickness,the lowest thickness before film rupture,stability index was calculated to describe the capabilities of surfactants to stabilize water films.We investigated the influence of film size and simulation duration on the critical thickness and proved that our model is reasonable. Stability index versus surfactant concentration curve suggests that the capabilities of three surfactants,to stabilize water film decrease in the order of.The simulated results have been validated by foam generation and decay experiment results,which indicates this method for predicting stability of water/surfactant film is feasible.更多还原