Tunable Orientation and Assembly of Polymer-Grafted Nanocubes atFluid-Fluid Interfaces

Self-assembly of faceted nanoparticles is a promising route for fabricating novel nanomaterials but fabricating low-dimensional assemblies with tunable particle orientation is challenging. In this talk, I will demonstrate that trapping surface-functionalized faceted nanoparticles at fluid-fluid interfaces is a viable approach for controlling particle orientation and facilitating their assembly into low-dimensional superstructures. Using molecular dynamics simulations of polymer-grafted nanocubes in a polymer bilayer, we show that the nanocubes can be induced into different orientations by tuning the graft density and their interaction with the two polymer layers. The orientational preference of the nanocubes is found to be governed by an interplay between the interfacial area occluded by the particle, the difference in interactions of the grafts with the two layers, and the stretching of polymer grafts towards the interface. The resulting homogeneously oriented nanocubes were then shown to assemble into unusual architectures, including rectilinear strings, close-packed sheets, bilayer ribbons, and perforated sheets. The assembly approach could therefore be used to fabricate unique arrays of nanoparticles with possible applications in plasmonics, optics, and catalysis.