Stabilization of ultrathin nanowires by self-assembly into bundles

Abstract

The relative tendency of freely dispersed and bundled gold nanowires to break up along their length by the Rayleigh–Plateau instability is investigated both experimentally and theoretically. Small angle X-ray scattering, in combination with transmission electron microscopy, reveal that the bundling of nanowires can enhance their stability. The experimental observation is rationalized by a linear perturbation analysis of a representative unit cell of bundled wires. A stability map is constructed for a bundle of nanowires to display the sensitivity of the Rayleigh–Plateau instability to the number and size of contacts with nearest neighbors per nanowire, and to the ratio of interfacial energy to surface energy. Stabilisation is enhanced by allowing the bundle of wires to sinter freely: a criterion for this kinetically-based stabilisation is given in terms of the ratio of pinch-off time for the instability to the sintering time to form the necks between nanowires.