Phase separation of ferrocolloids: The role of van der Waals interaction

摘要

Equilibrium phase separation of sterically stabilized ferrocolloids are theoretically studied. The model, which is easily generalized to different physicochemical procedures of ferrocolloid stabilization and gives a quantitatively exact description of computer-calculated phase diagrams of the Stockmayer fluid, is developed. The application of this model for describing the phase separation of real ferrocolloids has demonstrated that, in a ferrocolloid, the key role belongs to the presence of fairly large particles whose van der Waals attraction is insufficiently screened by stabilizing layers. Phase separation can proceed exactly owing to the presence of such particles in ferrocolloids and is due to the joint action of van der Waals and magnetodipole forces under the conditions when the intensity of the latter forces is not sufficient for formation of stable chain aggregates hindering phase separation.