Papers by Keyword: Colloidal Suspensions

Abstract: We used Brownian Dynamic simulation to study structural and dynamic properties of bi-disperse colloidal suspensions. The size ratio of large to small particles in the bi-disperse colloidal suspension is set at 5:1 and 10:1. We studied the interaction of aggregates (clusters) formed through DLVO (Derjaguin, Landau, Verwey and Overbeek) and soft sphere interactions in a bi-disperse suspension. The dynamic properties of bi-disperse is correlated by varying the size ratio of bi-disperse particles, it is found that the mobility is decreased at size ratio of large to small particles is 5:1. This is despite the percolating particle gels formation was disrupted by larger particles at higher size ratio.

Abstract: Motivated by applications in the field of nanomanufacturing, we perform large-scale numerical simulations of the electrophoretic deposition of suspensions of charged colloids in an electrolyte. A simulation method is developed to model the full deposition process that captures linear electrophoresis, dipolar interactions, van-der-Waals forces, steric interactions, Brownian motion, as well as electric and hydrodynamic interactions with the electrodes. Using a fast algorithm, suspensions of up to 5,000 particles are simulated, and results are reported for the final deposit microstructure as a function of field strength. The simulation results demonstrate that regular crystalline colloidal assemblies are obtained at low field strengths and volume fractions, while more random structures with frequent defects are formed in stronger fields and at higher volume fractions, in agreement with recent deposition experiments.

Abstract: The electrophoretic deposition of polystyrene/divinylbenzene (PS/DVB) star polymer-europium sulphide (EuS) nanocomposite films from a colloidal suspension is reported. Liquid suspension, containing both the PS/DVB star polymer and EuS nanocrystals were prepared by separately injecting dichloromethane (DCM) based solutions of EuS nanocrystals and of the star polymers, respectively, into a stratified liquid combination of hexane and DCM. Scanning electron microscopy illustrates images of the dependence of surface morphology on nanocrystal concentration of the PS/DVB-EuS star polymer film. These polymer-encased nanocrystal films may be a more practical option for the fabrication of magneto-optical thin film devices, such as optical switches, optical isolators, and optical memories.