Diffusiophoretically induced interactions between chemically active and inert particles.

Area of Science:

• Colloid and Interface Science
• Chemical Physics
• Fluid Dynamics

Background:

• Diffusiophoresis enables chemically inert particles to move along concentration gradients created by active particles.
• Understanding particle interactions is crucial for designing active colloidal systems.

Purpose of the Study:

• To investigate the diffusiophoretic motion of inert particles near chemically active particles.
• To analyze the dynamics and self-assembly of reactive and inert spheres in solution.
• To explore the influence of sphere size ratio on dimer motor characteristics.

Main Methods:

• Analytical solutions of continuum reaction-diffusion and Stokes equations.
• Microscopic simulations of particle dynamics.
• Analysis of streamline and flow velocity fields.

Main Results:

• Relative velocities of spheres are similar in fixed and free systems.
• Local and global flow structures differ significantly between the two systems.
• Freely moving spheres form self-assembled dimer motors that propel themselves.
• Fluid flow direction changes upon dimer formation.
• Sphere size ratio impacts flow field characteristics.

Conclusions:

• Diffusiophoresis drives self-assembly and propulsion in colloidal systems.
• Dimer formation leads to a self-propelled motor with altered flow dynamics.
• Active self-assembly can be controlled by manipulating sphere size in reactive systems.