Aspect ratio control of polymer microparticles in shear-yielding emulsion systems via rheology-mediated shape arrest

초록

Controlling the shape of polymer microparticles in emulsion systems remains challenging, as droplet deformation is typically followed by rapid relaxation toward spherical geometries. While microfluidic approaches enable precise shape control, their scalability is limited, whereas conventional emulsion methods offer high throughput but lack control over anisotropic particle formation. Here, we present a scalable strategy to control the aspect ratio of polymer microparticles in shear-yielding emulsion media through rheology-mediated shape arrest. By employing shear-thinning and shear-yielding media based on sodium alginate and corn starch, droplet deformation is preserved during emulsification, enabling the formation of elongated microparticles without the need for microfluidic confinement. The evolution of particle morphology is governed by the interplay between medium rheology, interfacial tension, and applied shear, which is captured through a capillary-number-based framework. A consistent correlation between particle aspect ratio and capillary number is observed, suggesting that microparticle elongation can be tuned by controlling process parameters such as stirring speed, medium viscosity, and surfactant concentration. This approach enables scalable manufacturing of anisotropic polymer microparticles and offers a process design strategy for tailoring particle morphology in emulsion-based systems.

키워드