Structure-Kinetics Relationships in Micellar Solutions

表面活性剂在流体界面上的吸附动力学在表面活性剂在油墨、喷雾剂、润滑剂、洗涤剂、乳液和多相胶体悬浮液中的各种应用中起着关键作用。水中的表面活性剂通常高于临界胶束浓度;因此，胶束或其他聚集体在确定表面活性剂向界面的质量传递中起重要作用。以前的工作已经表明，胶束过程的动力学知识-胶束分解，扩散和吸附-是必不可少的，即使是定性的了解胶束溶液中的吸附动力学。然而，我们对胶束动力学的理解还远远没有完成：胶束不吸附的标准假设通常是无效的;几乎没有任何关于远离平衡的胶束溶液的动力学数据;通过不同技术测量胶束分解速率可能相差几个数量级;我们从表面活性剂结构预测胶束过程速率常数的能力是有限的。这一建议将发展一个定性和定量的理解胶束的质量传输过程中的影响。表面活性剂的结构将系统地变化，其对胶束结构，胶束破裂速率和扩散率的影响进行测量。将在液体射流和溢流圆筒中以1 ms - 1 s的时间尺度研究空气-液体界面的吸附速率，其中独立测量流体力学和吸附速率。有限元建模将用于测试胶束溶液中吸附动力学的定量模型。该项目的产出将是（i）对化学结构、胶束结构和动力学参数之间关系的理解，（ii）胶束溶液中吸附动力学的经验证的定量模型。

The kinetics of adsorption of surfactants at fluid interfaces plays a critical role in diverse applications of surfactants in inks, sprays, lubricants, detergents, emulsions and in multiphase colloidal suspensions. Surfactants in water are commonly above the critical micelle concentration; consequently, micelles or other aggregates play an important role in determining mass transport of the surfactant to an interface. Previous work has shown that a knowledge of the kinetics of micellar processes - micelle breakdown, diffusion and adsorption - is essential for even a qualitative understanding of the dynamics of adsorption in micellar solutions. Yet our understanding of micellar kinetics is far from complete: the standard assumption that micelles do not adsorb is not generally valid; there is hardly any kinetic data on micellar solutions far from equilibrium; measurements of micelle breakdown rates by different techniques may differ by orders of magnitude; our ability to predict rate constants for micellar processes from the structure of the surfactant is limited. This proposal would develop a qualitative and quantitative understanding of the effect of micelles on mass transport processes. The surfactant structure will be systematically varied and its effect on the micelle structure, micelle breakdown rates and diffusivity measured. The rate of adsorption to the air-liquid interface will be studied on the timescale of 1 ms - 1 s in a liquid jet and overflowing cylinder, in which both the hydrodynamics and adsorption rate are independently measured. Finite element modelling will be used to test quantitative models for adsorption kinetics in micellar solutions. The outputs of the project will be (i) an understanding of the relationship between chemical structure, micellar structure and kinetic parameters, (ii) a validated, quantitative model for adsorption kinetics in micellar solutions.