Reconfigurable liquids enabled by dynamic covalent chemistry

Abstract

Nanoparticle surfactants (NPSs) that form via the reversible non‐covalent interactions between nanoparticles (NPs) and polymer ligands at the oil‐water interface have received great attention in constructing structured liquids with unique stimuli‐responsiveness. Introducing dynamic covalent interactions to generate NPSs is expected to achieve a balance between high mechanical strength and dynamic responsiveness of the interfacial assemblies. Here, we present the formation, assembly, and jamming of a new type of NPS by the co‐assembly between polydopamine NPs (PDA NPs) and poly(styrene‐co‐methacrylamidophenylboronic acid) at the oil‐water interface. Dynamic covalent boronate ester bonds form in situ at the interface and show multiple responsiveness when applying stimuli such as pH, H2O2, and temperature, allowing the controlled assembly/jamming of NPSs and reconfiguration of liquid constructs. Due to the photothermal property of PDA NPs, the temperature responsiveness of boronate ester bonds can also be triggered by irradiating the biphasic system with near‐infrared (NIR) light. Moreover, when bringing two droplets encapsulated with NPSs into contact and irradiating the contact area by NIR, thermal welding of droplets can be realized, offering a straightforward to construct droplet networks and modular liquid devices.