(583f) Wettability Effects on Interfacial Rheology and Stability of Particle-Laden Oil/Water Interfaces

The stabilization of interfaces in presence of colloidal particles is commonplace in various applications such as consumer care products, food, and pharmaceutics. The formation of particle networks at interfaces, influenced by interparticle interactions, plays a pivotal role in stabilizing emulsions and foams. By tuning the particle characteristics such as size, shape, and wettability, the interparticle interactions and resulting interfacial rheological behavior can be tailored, leading to complex responses of the particle-laden interfaces. Understanding the effects of particle attributes on the interparticle interactions and network formation is essential for elucidating the role of interfacial rheology in the stabilization mechanism of multiphase formulations, with applications for droplet coalescence. In this work, we experimentally investigate the impact of particle wettability on the interparticle interactions at the oil/water interface, and the response of such particle-laden interfaces to applied stresses. Using a Langmuir trough coupled with an inverted microscope, we examined the microstructure of the interfacial monolayers and their response to applied compressions, while the interfacial shear rheology of the particle networks was investigated using the double wall ring geometry. Our results show distinct rheological responses for particles of different wettabilities, highlighting the significance of surface modifications in governing interfacial behavior with consequences for droplet coalescence dynamics, including the coalescence time and characteristic thinning dynamics.