Coupled molecular dynamics-Monte Carlo modeling of gold nanowire surface fasteners

A novel multiscale model is developed to investigate the mechanical performance of gold nanowires surface fasteners. The cold welding of two contacting nanowires of different diameters and overlapping depth was simulated using molecular dynamics simulations. The strength of the welded interface was obtained via tensile simulations performed at temperatures up to 500 K. A Monte Carlo algorithm was developed to determine the bulk properties of the nanofastener by calculating the average number of welded joints per unit area. Our model shows that the nanojoints are formed by solid-state diffusion and intermixing of the interface atoms. The nanojoints strength increases with the increase of the preloading pressure, leading to the fracture of the nanowire outside the welded region. The results further show that the strength of the nanojoint slightly increases with the increase of the nanowires diameter beyond 10 nm. The effective strength of the fastener was found to increase by four orders of magnitude when the nanowire diameter decreased from 200 nm to 3 nm. Increasing the surface density and improving the patterning accuracy of the nanowire arrays are critical in improving the adhesive performance. The results of the multiscale model are in good agreement with previous experimental measurements.