Colloidal using capillary interaction

Desai TR, et al. Determination of surface free energy of interactive dry powder liposome formulations using capillary penetration technique. Colloids Surf B Biointerfaces 22(2) 107-113, 2001. 

With the viscosity of a liquid we mean the resistance to flow of that particular liquid. This resistance is caused by internal friction and other interactions between the particles. Among other things, viscosity is dependent on temperature, the solid volume fraction and the properties of the particles. The viscosity of normal liquids, solutions and lyophobic colloids which are not too concentrated and contain symmetrical particles is measured by allowing a certain volume to flow through a capillary and measuring the time required by the liquid to flow through it. In figure 5.10 you can see the instrument which is used for this measurement the Ostwald viscometer. 

A variety of methods have been demonstrated for crystallizing monodispersed spherical colloids (such as polymer beads and silica spheres) into long-range ordered lattices. Some of the commonly used ones include sedimentation, self-assembly via repulsive electrostatic interaction, ordering via attractive capillary forces, and crystallization under physical confinement. 

Besides equilibria in the liquid phase (proteolytic, complex forming, etc.) that influence directly the values of effective mobilities of compounds to be separated, it is necessary to also establish, in the electrophoretic system, equilibria between the liquid and solid phase. In electrophoretic techniques which use solid stabilizing media adsorption of solutes on the sorbent surface is the main consideration. In capillary methods, and with colloid particles, similar effects have also to be considered (the surface of the solid phase that is in contact with the liquid phase is, with respect to the volume of the liquid, rather large). In both these latter cases the interaction between the solid and liquid phases participates in the formation of the electric double layer that conditions the electro-osmotic flow, and attributes the electric charge to colloid particles. 

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