Microemulsions, i.e. dispersions of liquid droplets in another liquid in which they are not soluble, are versatile platforms for the design of functional soft materials, such as encapsulation-and-delivery systems or biomimetic assemblies. I will briefly illustrate these two approaches with some results from my PhD and postdoctoral research. During my PhD at ENS, I used interfacial complexation in water-in-oil emulsions to drive the accumulation of thermoresponsive polymers at the surface of water droplets, resulting in aqueous-core microcapsules with temperature-dependent properties (polarity, fluidity, permeability). As a postdoc associate at NYU, my current research focuses on the design of biomimetic colloidal materials via the programmable assembly of DNA-functionalized oil microdroplets in water using enzymatic reactions. By controlling the organization of droplet clusters in time and space, I show that this system replicates key features of living cellular aggregates, such as dynamic reorganization and response to chemical cues. This programmable system also opens pathways to the design of active and adaptive soft materials at the colloidal scale, including colloidal active gels or encapsulation systems.