短链烷基对多取代烷基苯磺酸盐界面性质的影响

摘要

The interfacial dilational rheological properties of 2,5-diethyl-4-nonyl benzene sulfonate(292),2,5-dipropyl-4-nonyl benzene sulfonate(393),and 2,5-dibutyl-4-nonyl benzene sulfonate(494) at air-water and decane-water interfaces were investigated by drop shape analysis.The influences of ageing time,interfacial pressure,dilational frequency,and bulk concentration on their dilational elasticity and viscosity were expounded.The surface adsorbed film was found to be elastic in nature at lower bulk concentration,and its strength determined by the interactions between the molecules in the film.In contrast,a diffusion-exchange process between the surface and the bulk controlled the properties of film at higher concentration.The insertion of oil molecules weakened the interactions among the adsorbed molecules,causing the diffusion-exchange process to dominate the nature of the interfacial film.However,this effect of the oil molecules decreased with increasing short alkyl chain length.The strength of the surface film could be determined before the adsorption equilibrium,while the nature of the interfacial film varied after saturated adsorption because of the re-arrangement of the interfacial surfactant molecules.%利用悬挂滴方法研究了2,5-二乙基-4-壬基苯磺酸钠(292)、2,5-二丙基-4-壬基苯磺酸钠(393)和2,5-二丁基-4-壬基苯磺酸钠(494)在空气-水表面和正癸烷-水界面的扩张流变性质,考察了时间、界面压、工作频率及体相浓度对扩张弹性和粘性的影响.研究发现,在低表面活性剂浓度条件下,表面吸附膜类似弹性膜,其强度由膜内分子的相互作用决定;高浓度下体相与表面间的扩散交换过程控制表面膜的性质.油分子的插入导致界面吸附分子之间相互作用的削弱,扩散交换过程主导界面膜性质;但随着短链烷基长度增加,油分子的影响变小.表面膜的强度在吸附达到平衡前已经决定,而界面膜在吸附饱和后仍然随界面分子重排而变化.