Arrested coalescence in structured liquids.

Abstract

Structuring liquids can be achieved by the assembly and jamming of particles at the oil-water interface. However, this typically requires surface modification of particles or co-assembly with polymer ligands to enhance interfacial binding energies. Here, we show a simple and robust strategy to structure liquids by using water-soluble, star-shaped β-cyclodextrin (β-CD) derivatives, whose interfacial assembly is driven by supramolecular interactions with oil solvents. Three classes of solvents including alkanes, aromatic hydrocarbons and halohydrocarbons are examined, leading to distinct interfacial binding energies of β-CD derivatives and different liquid structuring and coalescence behaviors. In aromatic hydrocarbon/water biphasic systems, β-CD derivatives form jammed yet porous interfacial assemblies that combine mechanical rigidity with high free volume. As a result, the liquids are shapeable, reconfigurable and capable of arrested coalescence upon gentle contact, opening opportunities for programmable liquid constructs, soft robots, and related applications.