胶体及界面化学(第13章new)-dzx.ppt

Chapter 13. Electrostatic and polymer-induced colloid stability 13.1 Introduction 1. Colloid stability Colloid stability: The ability of a dispersion to resist coagulation. Kinetic stability(动力稳定性): Evaluated（评价） by kinetics. Thermodynamic stability(热力学稳定性): Evaluated by thermodynamics. Van der Waals force: attractive and is strong at short interparticle separation. The protection against van der Waals force is usually provided in one of two ways: Electrostatic force→electrical double layer. electrostatic stability(电稳定作用) Polymer repulsive force: The adsorbed polymer layer on dispersed particles masks(屏蔽、对抗) the attraction force of Van der Waals force. Polymer-induced stability(聚合物稳定作用) or steric stability(空间稳定作用). 2. Focus of this chapter The stability and the structure of dispersions; Structure: spatial(空间的) organization（构造、架构） of the colloidal particles. How interparticle forces influence the structure of a dispersion; How the influence of interparticle interaction energies on dispersion stability; How polymer influence the stability of dispersions. 13.2 Interparticle forces, structure and stability of dispersions To know the relation between interparticle forces and the microstructure of dispersions and the factors that determine such a relation. Interplay between interpartcle forces and structure Dominated by strong repulsion; Dominated by strong attraction; Intermediate situations. Interparticle forces and the corresponding microstructure of monodisperse colloids How interparticle forces and the concentration of the particles to determine the structure of dispersions. 13.3 Interaction energy curves and their dependence on the properties of the dispersion The Interaction energy curves are useful for developing quantitative measure of kinetic stability of dispersions. Such a study of stability is known as the DLVO theory (Derjaguin-Landau-Verwey-Overbeek, 1940). ΦT＝ΦR+ΦA （13-1） ΦT –Total interaction energy ΦR – R