Interfacial Dynamics of Drops from Emulsions to In-situ Formed Soft Particles

Multiphase systems are ubiquitous in natural and engineered processes, where interactions between distinct fluid phases govern stability, transport, and dynamic behavior. In such systems, interfaces play a key role, governing capillary forces, interfacial stresses, and mass transfer processes that ultimately determine system performance. While the mechanics of simple fluid interfaces are well understood, many practical applications involve complex fluids whose interfacial and bulk properties evolve in time due to chemical reactions or physical transformations. Understanding how these evolving properties influence interfacial dynamics remains a significant challenge. This thesis investigates how in situ colloidal particle formation and time-dependent internal phase evolution affect the behavior of oil-water interfaces under both static and dynamic conditions. The work focuses on reactive emulsion systems in which microemulsion formation and sol–gel chemistry enable the generation of surface-active colloidal structures directly at oil–water interfaces or within dispersed droplets. These systems provide a controlled platform to examine the coupling between interfacial material formation, evolving rheology, and macroscopic flow behavior. At static oil–water interfaces, in situ particle generation leads to the formation of interfacial assemblies that modify interfacial properties and introduce mechanical resistance to deformation. Under dynamic conditions, internal phase evolution and particle formation significantly alter filament thinning and pinch-off dynamics, resulting in slower thinning rates and increased filament stability compared to systems with liquid internal phases. During droplet impact, spreading, and evaporation on solid surfaces, internal phase transformations suppress spreading, reduce evaporation rates, and produce distinct final deposition morphologies characterized by heterogeneous and mechanically constrained deposits. This thesis establishes direct links between interfacial material formation, internal phase transitions, and dynamic interfacial behavior. The findings provide physical insight into how reactive emulsions can be used to engineer adaptive interfaces and offer strategies for controlling interfacial mechanics and deposition outcomes in applications such as coating, printing, enhanced oil recovery, and controlled material delivery.