Thermally Reconfigurable Double Emulsions Droplets with Tunable Morphologies and Spherical Aberrations

Reconfigurable emulsions engineered with specific structure designs, present a promising avenue for achieving customized properties and advanced optical functionality. Tri-phase reconfigurable emulsion droplets hold significant promise as micro-lenses with the potential to revolutionize optics and photonics applications. Here we introduce a novel type of triple-phase emulsions characterized by thermally reconfigurable shells, consisting of hydrocarbon and fluorocarbon components. These components exhibit temperature-dependent miscibility and are stabilized with unique velcro-mimicking surfactants, resulting in the formation of solid-like water/oil interfaces and water-in-oil-in-water double emulsions at a high temperature above the critical point. We assess the viscoelastic properties of these interfaces by characterizing the droplet deformation as they flow through sinusoidal channels, essentially functioning as a rheometer within polydimethylsiloxane devices. Upon temperature change, the hydrocarbon and fluorocarbon components within the oil shell undergo phase separation, causing the droplets to adopt a new morphology of inner water core and hydrocarbon phase engulfed by fluorocarbon shell. The droplet morphologies can be fine-tuned by adjusting the hydrocarbon-fluorocarbon volume ratio and micelles used in the outer water phase, giving rise to diverse and exotic structures. We also perform two-dimensional ray-tracing simulations of visible light traversing through those morphologies to calculate the longitudinal and transverse spherical aberrations to inform the design and selection of fluid lenses for various applications, paving the way for expanding the scope of optical applications and future transformative technologies.