Acid/alkali-resistant, stimuli-responsive, and shape-remodeled emulsion droplet assemblies with Ag nanocrystals as binding agents

Emulsion droplet assemblies have evolved dramatically in recent years due to their hierarchical structure and advanced performance. However, studies into their structural stability in strong acid/alkali aqueous environments and geometry reshaping of these assemblies are rare. Herein, novel emulsion droplet assemblies with Ag nanocrystals (Ag NCs) as “binding agents” are fabricated via a facile method combining Ag⁺ coordination and photoreduction. Due to the strong binding effect of the Ag NCs and their high chemical inertness against acids and bases, the resulting assemblies exhibit a remarkable acid/alkali resistance, which makes them distinct from previous emulsion droplet assemblies. Benefiting from the chloride corrosion and photothermal conversion features of Ag NCs, the resulting assemblies manifest a slow chloride ion response and fast NIR response. In addition, these assemblies can be easily processed into various shapes that can be further sculpted into more complex geometries through a combination of localized photoreduction and anion etching, which demonstrates the reshaping ability of the assemblies and allows the assemblies to adapt to a variety of spatial structure requirements in applications. This is the first work that acid/alkali-resistant and geometry reshaping of emulsion droplet assemblies have been addressed. As emulsion droplets show excellent potential as building blocks for assemblies, our findings offer new paradigms for the development and application of assemblies.