ABSTRACT The process of interfacial charge polarization is the physical background of many phenomena in colloids like electrophoresis, conductivity, dielectrics, electrooptics and dipolophoresis. On the basis of these phenomena numerous experimental methods have been suggested which give information on the equilibrium and non-equilibrium electric surface properties of colloid particles. The consideration of the charge component through the induced dipole moment (electric polarizability), the charge heterogeneity through the permanent dipole moment of the colloid particles represents next step of generalization of the electric properties of colloids following the average particle electric charge, which is the first largely studied approximation. It is of considerable interest to understand the participation of the different parts of electric double layer (dl) in the polarization mechanism as well as the influence of ionic conditions, adsorption of surface active substances, neutral polymers and polyelectrolytes. A characteristic feature of the polarization mechanism is its dynamics, connected with charge distribution and mobility, which in many cases is important for interparticle interactions and colloid stability. The increase of the particle concentration leads to changes in charge distribution and interfacial charge dynamics. So it is possible to study the transition from very diluted (ideal gas approximation where single particles properties are essential) to concentrated systems (disordered - liquid approximation and ordered - colloid crystals). Thus the properties of concentrated systems could be related to single particles properties in diluted systems.
Buy this Article
|
