Anti-vapor-penetration and Condensate Microdrop Self-Transport of Superhydrophobic Oblique Nanowire Surface under High Subcooling

It is well-known that microscale gaps or defects are ubiquitous and can be penetrated by vapor, resulting in the failure of superhydrophobic effect and undesired condensate flooding under high subcooling. Here, we propose and demonstrate that such problem can be solved by the oblique arrangement of nanowires. Such a structure has been demonstrated to own anti-vapor- penetration and microdrop self-transport functions under high subcooling, unaffected by the microscale gaps. This is because vapor molecules can be intercepted by oblique nanowires and preferentially nucleate at near-surface locations, avoiding the penetration of vapor into the microscale gaps. As-formed microdrops can suspend upon the nanowires and have low solid-liquid adhesion. Besides, oblique nanowires can generate asymmetric surface tension and microdrop coalescence can release driving energy, both of which facilitate the microdrop self-removal via sweeping and jumping ways. This new design idea helps develop more advanced condensation mass and heat transfer interfaces.