Vorticity-Aligned Droplet Bands in Sheared Immiscible Polymer Blends Induced by Solid Particles

Area of Science:

• Fluid mechanics
• Materials science
• Colloid science

Background:

• The behavior of complex fluids is significantly influenced by solid particle incorporation.
• Understanding particle-droplet interactions is crucial for controlling fluid microstructure.

Purpose of the Study:

• To investigate the formation and orientation of droplet bands in immiscible polymer blends.
• To elucidate the role of interfacially active microspheres in dictating fluid organization under shear flow.

Main Methods:

• Experimental observation of droplet band formation in polymer blends with interfacially active microspheres.
• Analysis of particle bridging, droplet coalescence, and band anisotropy.
• Application of Jeffery orbit theory and confinement effects to explain orientation.

Main Results:

• A monolayer of microspheres bridges droplets into vorticity-aligned bands at intermediate concentrations and low shear rates.
• Strong particle bridging and rigid anisotropic droplet bands cause vorticity orientation.
• Increased particle aspect ratio restrains band formation due to reduced coverage and enhanced coalescence.

Conclusions:

• Interfacially active microspheres can organize immiscible polymer blends into anisotropic droplet bands.
• Particle bridging ability and band rigidity are key factors for vorticity alignment.
• Particle geometry significantly impacts the stability and morphology of these organized structures.