Bridge-to-drain: How nanoparticles can promote coalescence in model polymer blends

Area of Science:

• Materials Science
• Colloid and Surface Science
• Fluid Dynamics

Background:

• Multiphase liquids with droplet-in-matrix morphology are crucial in various industries.
• Controlling droplet size is key to material performance.
• Nanoparticles at interfaces can stabilize or destabilize emulsions.

Purpose of the Study:

• To investigate the mechanism of nanoparticle-induced coalescence in multiphase fluids.
• To understand how low nanoparticle concentrations can promote coalescence.
• To identify conditions for utilizing this phenomenon in material design.

Main Methods:

• Microfluidics used to study coalescence in a model PDMS/PB blend.
• Low concentrations (up to 0.2 wt%) of ZnO nanoparticles employed.
• Analysis of hundreds of droplet coalescence events.

Main Results:

• Nanoparticles significantly promoted coalescence despite negligible effects on rheology and interfacial energy.
• A
• bridge-to-drain
• mechanism was identified where nanoparticles bridge droplets, facilitating matrix film drainage.
• This mechanism depends on partial droplet coverage and particle bridging ability.

Conclusions:

• Nanoparticle-induced coalescence can occur via a novel
• bridge-to-drain
• mechanism.
• A critical surface coverage fraction determines whether nanoparticles promote or stabilize coalescence.
• Understanding this phenomenon allows for rational design of multiphase fluids.