Compare study between icephobicity and superhydrophobicity

Highlights: • Relationships between adhesion work and the microstructures are quantitatively established in different wetting state. • Adhesion work of a water droplet is strangely larger than that of its frozen (namely, W_aw > W_ai, a challenging question). • Theoretical explanation for anti–icing and icephobicity of superhydrophobic surface. • Adhesion work of the frozen water droplet may be used for characterization of contact state. -- Abstract: Although surface microstructures is the key to superhydrophobicity, and possibly leads to significant icephobicity when a water droplet freezes on superhydrophobic surfaces (SHS), thermodynamic mechanisms responsible for the icephobicity and anti–icing still need to be further studied. For this reason, we established the relationships between some quantities, i.e., contact angle (CA) together hysteresis (CAH), adhesion work and the microstructures by a three–dimension (3–D) surface model, and theoretically explained the anti–icing and icephobicity from the SHS. Our theoretical and experimental study indicate, the adhesion work (W_ai) of a frozen water droplet to the SHS in composite wetting state (CWS) is apparently less than that in the non–composite wetting state (NCWS). Therefore it is necessary to create such CWS by designing surface micro/nanostructure. Further study also shows, the adhesion work (W_aw) of a water droplet to the SHS is larger than that (W_ai) of their frozen, thus implying decrease of the adhesion work after icing. This will improve on the understanding of the SHS for anti–icing and icephobicity.