The Leidenfrost Effect at the Nanoscale

Abstract

Nanotechnology has been presenting successful applications in several field, such as electronics, medicine, energy and new materials. However, the high cost of investment in facilities, equipment and materials as well as the lack of some experimental analysis at the nanoscale can restrain research in nanotechnology. The implementation of accurate computer models can alleviate this problem. This work investigates the Leidenfrost effect at the nanoscale using molecular dynamics simulation. Models of water droplets with diameters of 4nm and 10nm are simulated over gold and silicon substrates. To induce the Leidenfrost effect, droplets at 293K were deposited on the substrates at 373K. As a baseline, simulations were run with substrates at room temperature. Results show that for substrates at 293K, the 4nm droplet has higher position variability than the 10nm droplets. For substrates at 373K, the 4nm droplets have higher velocities than the 10nm droplets. The wettability of the substrate also influences the Leidenfrost. Droplets over the gold substrate which has hydrophobic characteristics have higher velocities as compared to droplets over silicon that has a hydrophilic behavior. Moreover, the Leidenfrost effect was observed at the boiling temperature of water (373K) which is a significantly lower temperature than reported in previous experiments at the microscale.