Confinement effects on diffusiophoretic self-propellers

TL;DR

This paper theoretically investigates how spatial confinement influences the self-propulsion of chemically active particles, revealing that confinement can enhance their velocity despite increased viscous friction.

Contribution

It provides a theoretical analysis of confinement effects on diffusiophoretic particles, highlighting the balance between increased gradients and friction.

Findings

Confinement increases both composition gradients and viscous friction.

Overall, confinement leads to an increase in particle velocity.

Velocity remains small when steric repulsion is the only interaction.

Abstract

We study theoretically the effects of spatial confinement on the phoretic motion of a dissolved particle driven by composition gradients generated by chemical reactions of its solvent, which are active only on certain parts of the particle surface. We show that the presence of confining walls increases in a similar way both the composition gradients and the viscous friction, and the overall result of these competing effects is an increase in the phoretic velocity of the particle. For the case of steric repulsion only between the particle and the product molecules of the chemical reactions, the absolute value of the velocity remains nonetheless rather small.