Electrophoresis of a Particle at an Arbitrary Surface Potential and Double Layer Thickness: Importance of Nonuniformly Charged Conditions

摘要

Recent advances in material science and technology yield not only various kindsnof nano- and sub-micro-scaled particles but also particles of various charged conditions such asnJanus particles. The characterization of these particles can be challenging because conventionalnelectrophoresis theory is usually based on drastic assumptions that are unable to realisticallyndescribe the actual situation. In this study, the influence of the nonuniform charged conditionsnon the surface of a particle at an arbitrary level of surface potential and double layer thickness onnits electrophoretic behavior is investigated for the first time in the literature taking account of theneffect of double-layer polarization. Several important results are observed. For instance, for thensame averaged surface potential, the mobility of a nonuniformly charged particle is generallynsmaller than that of a uniformly charged particle, and the difference between the two dependsnupon the thickness of double layer. This implies that using the conventional electrophoresisntheory may result in appreciable deviation, which can be on the order of ca. 20%. In addition, thennonuniform surface charge can yield double vortex in the vicinity of a particle by breakingnthe symmetric of the flow field, which has potential applications in mixing and/or regulating thenmedium confined in a submicrometer-sized space, where conventional mixing devices are inapplicable.