表面活性剂(第三章).ppt

（表面活性剂功能及应用） （1）增溶作用 增溶作用的方式 （1）非极性分子在胶束内核的增溶 增溶作用的方式 （2）在表面活性剂分子间的增溶 增溶作用的方式 （3）在胶束表面的吸附增溶 （2）乳化与破乳作用--Emulsification By Surfactants 1.General Remarks （1）Paints, polishes, pesticides, metal cutting oils, margarine, ice cream, cosmetics, metal cleaners and textile processing oils etc. are all emulsions or are used in emulsified form. （2）An emulsion is a significantly stable suspension of particles of a liquid of a certain size within a second, immiscible liquid. macroemulsions ，microemulsions （3）Based on the nature of the dispersed phase, emulsions can also be classified into three types a) oil-in-water (o/w), b) water-in-oil (w/o), c) oil-in-water-in-oil (o/w/o), water-in-oil –in-water(w/o/w), （4）Distinguishment of the emulsions (鉴定方法) Dilution （稀释法） b) Conductivity measurement（电导法） c) Colouration （染料法） d) Refractive index method（散射指数法） e) Filter paper test （滤纸润湿法） 2. Stability of Emulsions（乳状液的稳定） The stabilization the emulsifier does is as follow: ?The emulsifier molecules adsorb at the L/L interface as an oriented interfacial film; 液液界面膜的乳化剂分子 ???Reduces the interfacial tension markedly; 明显减少界面张力 ??Decreases the rate of coalescence of the dispersed liquid particles by forming mechanical and/or electrical barriers around them. 固体粉末的加入 （1）Factors affecting the emulsion stability 影响稳定的因素 A--Physical nature of the interfacial film resulting from the adsorbed surfactants: 吸附层界面膜的属性 B--Existence of an electrical or steric barrier to coalescence on the dispersed droplets: 界面电荷 C--Viscosity of the continuous phase: 连续相的粘度 D--Size distribution of droplets: 液滴的大小 E--Phase volume ratio:相体积比例 F--Temperature: 温度 （2）Inversion of Emulsions Emulsions may be converted from w/o into o/w and vice versa by varying some of the conditions: A—The order of addition of the phases B—The nature of the emulsifier C—The phase volume ratio D—The temperature E—Other additives There are only some general guidelines that may be of helpful in selectin