Tunable Multimodal Drop Bouncing Dynamics and Anti-Icing Performance of a Magnetically Responsive Hair Array

Anti-icing
materials that can efficiently limit ice formation have
a strong potential to replace existing anti-icing techniques, such
as Joule heating, chemical release, or mechanical removal, which are
usually inefficient, expensive, and environmentally harmful. In this
study, an anti-icing material based on a magnetically responsive hierarchical
hair array that can actively modulate drop bouncing dynamics is presented.
The magnetically responsive hair array exhibits an immediate and reversible
structural bending motion in response to an external magnetic field.
The array also exhibits superhydrophobicity, regardless of its tilt
angle, due to the tapered geometry of the hairs and the multiscale
surface roughness of the array. Due to its dynamic structure and water-repellent
characteristics, the array can induce distinct multiple modes of drop
bouncing behavior by adjusting its structural bending state in a reversible
fashion. Three different types of bouncing behavior, namely, quasi-pancake
bouncing, directional bouncing, and macrotexture-induced droplet fragmentation,
can be obtained with the vertical, tilted, and fully bent hair arrays,
respectively. We demonstrate that the dynamically controllable drop
bouncing behavior of the magnetically responsive hierarchical array
enables the efficient and robust prevention of ice formation and accumulation.