How Do Colloidal Nanoparticles Move in a Solution under an Electric Field?: In Situ Light Scattering Analysis

Abstract

Understanding the dynamics of colloidal nanoparticles (NPs) in a solution is the key to assembling them into solids through a solution process such as electrophoretic deposition. In this study, newly developed in situ analysis with light scattering is used to examine NP dynamics induced by a non-uniform electric field. We reveal that the symmetric directions of moving NP aggregates are due to dielectrophoresis between the cylindrical electrodes, while the actual NP deposition is based on the charge of NPs (electrophoresis). Over time, the symmetry of the dynamics becomes less evident, inducing feeble deposition as the less-ordered dynamics become stronger. Eventually, two separate deposition mechanisms emerge as the deposition rate decreases with the change in the NP dynamics. Furthermore, we identify the vortex-like NP motion between the electrodes. These in situ analyses provide insights into the electrophoretic deposition mechanism and NP behavior in a solution under an electric field for fine film construction.

Coupling‐Grafting‐Ultrasonication Modification of Electrophoretic Particles for Fast Response and High Contrast Ratio Electrophoretic Display

“…Understanding the dynamics of colloidal nanoparticles in solution is key to analyzing the experimental phenomena they produce and improving the performance of colloid-based technologies. [29,30] In order to understand the dynamics of electrophoretic particles driven by the electric field, we developed an electrophoretic particle dynamics simulation model to explore how the grafting thickness of different white electrophoretic particles affects EPD ink performance. Based on the electrostatic force and drag force acting on the particles and their electric double layer as a whole, the mobility of particles μ in nonpolar solvent meets Debye-Hückle limit and can be described as: [31]…”