Ultrafast Impact Superspreading on Superamphiphilic Silicon Surfaces for Effective Thermal Management.

Abstract

Controllable impact spreading behavior is critical for effective thermal management of spray cooling. However, splash and retraction are common problems on hydrophobic (HPB) and hydrophilic (HPL) surfaces. Herein, by regulation of surface wettability, we report a controllable ultrafast impact superspreading behavior (superspreading time of ∼3.0 ms) without splash and retraction on superamphiphilic (SAPL) silicon surfaces. Analysis of dynamic wetting processes combined with observation of lateral force microscopy images on SAPL surfaces reveals the existence of a precursor film at the spreading edge induced by heterogeneous surface wettability at nanoscale. Further study indicates that the inhibition of splash results from the high liquid flux in precursor film, which suppresses the interposition of air at the spreading edge. The reduction of Laplace forces owing to the presence of precursor film inhibits retraction at the spreading frontier. Taking advantage of this impact superspreading behavior on SAPL surfaces, effective heat dissipation is demonstrated, offering uniform and high heat flux for the spray cooling process.