Responsive Interfacial Assemblies

We have developed versatile approach to generate photoresponsive microcapsules by assembling supramolecular NPSs (s-NPSs) at the oil-water interface. Different from traditional NPSs, mainly formed by electrostatic interactions, the s-NPSs used here consist of water soluble α-cyclodextrin (α-CD) modified gold NPs (α-CD NPs) and oil-soluble polymer ligand, azobenzene terminated poly-L-lactide (Azo-PLLA). The host-guest molecular recognition between the α-CD and Azo functionalities can be dynamically controlled by using light as an external trigger, toggling the assemblies encapsulating the microcapsules from a jammed state to an unjammed state, enabling a jamming-controlled diffusion and release of cargoes dispersed in the droplets. Since the size of the droplet can be arbitrarily large or small, this fascinating behavior can also be realized in macroscopic structured liquids having a cubic shape, where the shape of liquids can be changed from a highly nonequilibrium shape to the classic spherical shape with no change in the volume by the jamming-to-unjamming transition of the interfacial assembly of s-NPSs. Similarly, s-NPS, based on the molecular recognition of ferrocene (Fc) and β-cyclodextrin (β-CD) at the oil-water interface. Present an alternative strategy to generate responsive assemblies. Normally, uncharged Fc is strongly bound in the cavity of β-CD by host–guest recognition, whereas the charged Fc⁺ dissociates rapidly.  This association and dissociation effect can be reversibly manipulated by a redox process.   As a result, a desirable assembly/jamming and disassembly/unjamming of NPSs is achieved, leading to an efficient encapsulation and release of cargo. The s-NPSs exhibit remarkably high interfacial activity.