Eliminating Capillary Coalescence of Nanowire Arrays with Applied Electric Fields

Surface tension induces significant forces on wetted nanostructures, such as vertically oriented nanowire arrays, that can force them to aggregate when dried. This aggregation decreases the homogeneity and surface area of the array, often inhibiting their intended application. These aggregation forces are eliminated by introducing small electric fields (similar to 100 V/m) during drying, providing a simple approach that is applicable to a broad range of nanowire materials, diameters, lengths, and spacing. A model based on the forces acting on two nanowires shows that electrostatic repulsion, rather than field-induced changes to the surface tension, provides the necessary forces to prevent aggregation. These calculations also highlight the substantial surface tension forces acting on nanostructures and the difficulties associated with preventing their aggregation.