Abstract:

Transport of ions and colloidal particles in confined geometries is often important in widespread applications as they appear in many natural and artificial systems. However, the confinement brings an additional difficulty to the transport process due to the limited transport mechanisms that could be utilized in such systems. In the first section of this talk, we will discuss about the transport of ions in nanoscale pores and a control strategy for a direct application to the electrodeposition of nanowires. The growth of nanowires using this technique is intrinsically unstable, which presents a major challenge for energy applications. We show that the dynamics of this process is diffusion-limited, which results in a morphological growth instability. With such findings, we demonstrate a method to suppress the growth instability by spatially controlling the diffusion of ions using thermal gradient. In the second part, we will discuss about delivering microscale colloidal particles into dead-end geometries, which are commonly encountered in many critical applications such as drug or cosmetics delivery into skin pores and oil recovery from a deep underground reservoir. Particle transport into dead-end pores is often important, but is difficult to achieve owing to the confinement. We explore the possibility of diffusiophoresis, i.e. migration of a particle induced by solute gradient, as a means to enhance the transport of microscale particles in such geometries. Our findings have implications for all manners of controlled release processes, ranging from targeted drug delivery to personal healthcare products.