Femtosecond laser fabrication of square pillars integrated Siberian-Cocklebur-like microstructures surface for anti-icing

In a low-temperature environment, water vapor in the ambient air is easy to condense and form frost on superhydrophobic surfaces, causing a reduction of their anti-icing performance. In this paper, a femtosecond laser was used to fabricate two new structures on polytetrafluoroethylene (PTFE) substrates to compare anti-icing properties with conventional structures. The two new structures are Siberian-Cocklebur-like microstructures and square pillars integrated Siberian-Cocklebur-like microstructures; whereas, the conventional structures include microgrooves with small step size, microgrooves with large step size, and square pillars. We illustrate the mechanism of forming the new structures in the interaction between the femtosecond laser and PTFE. The two new structures have greater water contact angles in a low-temperature environment than the conventional structures. We set up corresponding models for various microstructures contacted with water droplets and discuss hydrophobicity diversity. The two new structures on PTFE can effectively inhibit the vapor condensation in the microstructures and improve the hydrophobic performance and anti-icing property of PTFE surfaces in a low-temperature environment.