Unveiling nanodroplet impact force on material interfaces

Nanodroplet impact on nanoscale material interfaces is widely involved in nanoscience and nanotechnology, affecting the technical reliability through complicated liquid‒solid interaction force, that is, the droplet impact force. However, our understanding of the nanodroplet impact force is still blank. Herein, we reveal that the nanoscale size (∼10 nm) and high impact velocity (>100 m/s) of nanodroplets lead to unique characteristics of impact force, significantly differing from those of macrodroplets (∼1 mm). The nanodroplet impact force profile holds a single-peak feature, which is independent of droplet parameters and material wettability. The significant water-hammer pressure induces the abnormal rising of impact force, yielding unexpectedly high peak values governed by the Mach number (more than 10 orders of magnitude higher than droplet gravity). Our findings of droplet impact force at the nanoscale reveal the potential challenge of the damage of material surfaces by nanodroplet impact, highlighting one crucial factor for advancing nanolithography and nanoprinting.