Bai Guiyu, Graham Michael D, Abbott Nicholas L
Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
Langmuir. 2005 Mar 15;21(6):2235-41. doi: 10.1021/la048238e.
We report quantitative measurements of Marangoni flows generated at the surfaces of aqueous solutions by using water-soluble redox-active surfactants in combination with electrochemical methods. These measurements are interpreted within the framework of a simple model that is based on lubrication theory and the proposition that the kinetics of the desorption of redox-active surfactants from the surfaces of aqueous solutions plays a central role in determining the strength of the Marangoni flow. The model predicts that the leading edge velocity of the Marangoni flow will decay exponentially with time and that the rate constant for the decay of the velocity can yield an estimate of the surfactant desorption rate constant. Good agreement between theory and experiments was found. By interpreting experimental measurements of electrochemically generated Marangoni flows within the framework of the model, we conclude that the desorption rate constant of the redox-active surfactant Fc(CH(2))(11)-N(+)(CH(3))(3)Br(-), where Fc is ferrocene, is 0.07 s(-)(1). We also conclude that the ionic strength of the aqueous solution has little effect on the desorption rate constant of the ferrocenyl surfactant.
我们报告了通过使用水溶性氧化还原活性表面活性剂并结合电化学方法，对水溶液表面产生的马兰戈尼流进行的定量测量。这些测量结果在一个基于润滑理论的简单模型框架内进行解释，该模型认为氧化还原活性表面活性剂从水溶液表面解吸的动力学在决定马兰戈尼流的强度方面起着核心作用。该模型预测，马兰戈尼流的前沿速度将随时间呈指数衰减，并且速度衰减的速率常数可以给出表面活性剂解吸速率常数的估计值。理论与实验结果吻合良好。通过在该模型框架内解释电化学产生的马兰戈尼流的实验测量结果，我们得出结论，氧化还原活性表面活性剂Fc(CH(2))(11)-N(+)(CH(3))(3)Br(-)（其中Fc是二茂铁）的解吸速率常数为0.07 s(-)(1)。我们还得出结论，水溶液的离子强度对二茂铁基表面活性剂的解吸速率常数影响很小。
