胶体化学(第13章)课件

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Chapter 13.Electrostatic and polymer-induced colloid stability,13.1 Introduction,1.Colloid stability,Colloid stability（,胶体的稳定性,）:,The stability 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.,.,Chapter 13.Electrostatic and,1,Van der Waals force:attractive and is strong at short interparticle separation.,There are two forces to against van der Waals force to protect colloid stability:,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,).,.,Van der Waals force:attractiv,2,2.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.,.,2.Focus of this chapterThe st,3,13.2 Interparticle forces,structure and stability of dispersions,To know the relation between interparticle forces,the microstructure of dispersions and the factors that determine such a relation.,Interpaly between interpartcle forces and structure,Dominated by strong repulsion;,Dominated by strong attraction;,Intermediate situations.,.,13.2 Interparticle forces,str,4,Interparticle forces and the corresponding,microstructure of monodisperse colloids,How interparticle,forces and the,concentration of the,particles to determine,the structure of,dispersions.,.,Interparticle forces and the c,5,13.3 Interaction energy curves and their dependence on the properties of the dispersion,The Interaction energy curves are useful for developing quantitative measure of kinetiv stability of dispersions.,Such a study of stability is known as the DLVO theory(Derjaguin-Landau-Verwey-Overbeek,1940).,T,R,+,A,（131）,T,Total interaction energy,R,Repulsion energy,A,-Attraction energy,.,13.3 Interaction energy curves,6,Boltzman constant，,1/k,thickness of electrical double layer,0,a constant,（132）,（133）,A-Hamaker constant,D-Distance between two particles,.,Boltzman constant，（132）（13,7,Effect of the,Hamaker constant,A,The height of,the potential energy barrier,.,.,Effect of theAThe height of.,8,2.Effect of the surface potential（,0,）,0,The height of the potential energy barrier.,.,2.Effect of the surface poten,9,3.Effect of Electrolyte concentration,k,-empirical adjustment,(,经验调整参数,),k,is quantity depends,on both concentration,and valence of the,indifference（不相干）,electrolyte.,k,The height of,the potential energy barrier.,.,3.Effect of Electrolyte conce,10,15.3 Polymer-colloid mixture,Polymers(,聚合物,)can be used to stabilize colloid and the role of polymers on colloid stability is considerably more complicated than electrostatic stability.,If the added polymers are polyelectrolyte(,聚电解质,),then a clearly have a combination of electrostatic effect as well as effects that arise solely(,单独地,)from the polymeric nature of the additive.,This combined effect is referred to as,electrosteric stabilization（,电空间稳定,）,.,.,15.3 Polymer-colloid mixturePo,11,A simplified representation of the effects of,polymers on the stability of dispersions,Bridging flocculation,（桥联絮凝）,Steric stabilization,（空间稳定）,Depletion flocculation,（过渡态絮凝）,Depletion stabilization,（过渡态稳定）,.,A simplified representation of,12,The structure of polymer chains in bulk,solution and near a solid interface,接枝,Segment,(链段),.,The structure of polymer chain,13,Interaction between,polymer-coated,particles.,Overlap(重叠)of,adsorbed polymer,layers on close,approach of dispersed,solid particles.,.,Interaction between Overlap(重叠,14,The various contributions to the interaction,energies between two polymer-coated particles.,The change in Gibbs,energy due to the,overlap of the tails,loops,and so on.,.,The various contributions to t,15,Interaction forces between polymer-coated,surface and their dependence on the type of,layers and quality of the solvent.,.,Interaction forces between pol,16,Combination of the electrostatic effects and steric stabilization.,T,R,A,S,S,Energy potential of steric stabilization,.,Combination of the electrostat,17,Effects of particles on the interface between,oil drops and water is like the steric effect of,polymers.,.,Effects of particles on the in,18,