Research On The Dynamics Of Silica Colloidal Particles In Potential Field

Colloids have important applications in agricultural production,medical and health,daily life,physical geography,industrial production,and wastewater treatment.The interaction between colloidal particles and the interaction between biological macromolecules(such as DNA,protein,etc.)have many similarities.The interaction between colloidal particles mainly includes shielding Coulomb repulsive potential,van der Waals attractive potential,and DLVO potential.The colloidal particles that do irregular thermal motion(Brownian motion)in the colloid are called Brownian particles.From the proposal of Brownian motion to the gradual perfection of the theoretical study of Brownian motion,people have more and more abundant research on various colloidal systems.In 1975,Saffman and Delbruck first studied the diffusion behavior of colloidal particles on the membrane,and combined the Stokes new equation and Orson tensor to give the correlation diffusion law between two particles in a two-dimensional plane.In the direction of the line connecting the centroids of the two particles(radial direction),C_?^*?^-1,in the vertical direction(horioontal direction)of the line connecting the centroids of the two particles,C_?^*?^-2.With the development of particle tracking technology and microscope imaging,the research of complex experimental systems(such as the model of colloidal particles that diffuse in the water-air interface)has obtained convenient material conditions.Studies have shown that the diffusion law of the correlation between two particles in a two-dimensional plane has multi-system universality.Based on the fluid dynamics model on the interface,this paper uses optical microscope and multi-particle tracking technology to explore whether the correlation law between the colloidal particles doing Brownian motion in the potential field(,)can still meet the above law.By changing the law of the potential field(,),exploring the inter-particle correlation motion,the main content includes two parts:(1)An experimental system of colloidal diffusion on a periodic potential field is studied.In the experiment,a colloidal solution of double-dispersed silica spheres is used to form a regularly arranged colloidal monolayer on the bottom substrate,which provides a periodic gravitational potential field(,)for the diffused particles on the top layer.Using optical microscopy and multi-particle tracking technology,we measured the particle number statistics of the top diffused particles,and used Boltomann's statistical colloidal particle distribution to describe the periodic potential field(,).At the same time,using the obtained energetics and dynamics information,we predict the sioe of the newly constructed two-dimensional gravitational potential field.(2)An experimental system of colloidal diffusion on a random and disordered potential field is studied.In the experiment,a mixture of double-dispersed silica spheres was used to form a randomly-filled colloidal monolayer on the bottom substrate,which provided a disordered gravitational potential field for the diffused particles on the top layer.Using optical microscopy and multi-particle tracking technology,we measured the particle number statistics of the top diffused particles,and introduced order parameters to describe the disordered gravitational potential field.Investigate how the relationship curve of the inter-correlation diffusion of two kinds of particles with distance is affected by the potential field defects and the random degree.Discuss how the hydrodynamic interaction is affected by the random degree of the potential field in a more complex two-layer particle system.Verify whether the scaling law found in the particle system limited by the smooth interface still exists in the particle system in the potential field.