水解离子和互补两性离子可溶性表面活性剂：表面分子反应动力学模拟及和频发生光谱学研究

An aqueous ionic surfactant 1-dodecyl-4-dimethylaminopyridinium (DMP) bromide and the corresponding zwitterion 2-(4-dimethylaminopyridinio)-dodecanoate (DPN) were explored by means of molecular dynamics (MD) simulations and, for the ionic system, by infraredvisible sum frequency generation (IR-VIS SFG). The molecular structure of the interfacial layer was investigated for the ionic and zwitterionic systems as a function of surfactant concentration, both in water and in salt (KF or KBr) solutions, by MD simulations in a slab geometry. The build up of the surface monolayer and a sublayer was monitored, and density and orientational profiles of the surfactants were evaluated. The difference between the ionic and zwitterionic systems and the effect of the added salt were analyzed at a molecular level. The results of MD simulations were compared to those of nonlinear optical spectroscopy measurements. Infrared visible sum frequency generation (IR-VIS SFG) was employed to study the DMP ionic surfactant in water and upon addition of simple salts. The influence of added salts on the different molecular moieties at the interface was quantified in detail experimentally.