On the geometric stability of an inorganic nanowire and an organic ligand shell

TL;DR

This paper investigates the stability of inorganic nanowires coated with organic ligand shells, analyzing how surface energy and diffusion influence their breakup into droplets, and provides stability maps to guide experimental stabilization efforts.

Contribution

It introduces a combined analytical and numerical approach to understand nanowire stability considering organic shells, highlighting conditions for stability and droplet formation.

Findings

Perturbation analysis accurately predicts pinch-off time and droplet size.

Organic ligand shells can stabilize nanowires against Rayleigh-Plateau instability.

Stability maps identify parameters for nanowire stabilization.

Abstract

The break-up of a nanowire with an organic ligand shell into discrete droplets is analysed in terms of the Rayleigh-Plateau instability. Explicit account is taken of the effect of the organic ligand shell upon the energetics and kinetics of surface diffusion in the wire. Both an initial perturbation analysis and a full numerical analysis of the evolution in wire morphology are conducted, and the governing non-dimensional groups are identified. The perturbation analysis is remarkably accurate in obtaining the main features of the instability, including the pinch-off time and the resulting diameter of the droplets. It is conjectured that the surface energy of the wire and surrounding organic shell depends upon both the mean and deviatoric invariants of the curvature tensor. Such a behaviour allows for the possibility of a stable nanowire such that the Rayleigh-Plateau instability is not energetically favourable. A stability map illustrates this. Maps are also constructed for the final droplet size and pinch-off time as a function of two non-dimensional groups that characterise the energetics and kinetics of diffusion in the presence of the organic shell. These maps can guide future experimental activity on the stabilisation of nanowires by organic ligand shells.