Interactions Between Colloidal Particles In Structured Water

In this thesis, we studied the static dielectric constant and the complex permittivity ofwater at various temperatures based on two-state model, and interactions between colloidalparticles in structured water. Amodel of interactions between colloidal particles wasdeveloped, and we discussed the effect of electrolyte concentration, surface dipole density andvalency of ion on interactions between colloidal particles.First, based on two-state model, the static dielectric constants of LDL and HDL werecalculated for the temperatures ranging from0℃to100℃with a thermodynamic approach.According to the microstructures of LDL and HDL, a mechanism was proposed to explain theslow and fast dielectric relaxations of liquid water. Our calculation indicated that the slowdielectric relaxation may be attributed to the reformation of hydrogen bonding network,accompanied with hydrogen bonds broken in the first coordination shells of LDL and HDL.However, the reorientation of the free “interstitial” water may result into the fast relaxation.We established the relation among water dipole moment, charge field and field generatedby other water molecules. We obtained a differential equation set containing water dipolemoment, which describes relation among surface charge density, surface dipole density,concentration of electrolyte, surface dipole density, valence of ion and distance between plates.By solving the differential equation group, we obtained distribution of water dipole andelectric potential, We also calculated the free energy and the interaction forces betweencolloidal particles.Compared with the interaction force between colloidal particles calculated on the basisof DLVO theory:(1) the interaction force between colloidal particles calculated on the basis ofour theory is stronger;(2) the interaction force between colloidal particles calculated based onour theory decreases slower with the distance between plates, and the range of the calculatedinteraction is longer. It reflects the feature of hydration force.