Nepenthes inspired superhydrophobic surfaces with multiple functions via femtosecond laser and chemical fluorination

Titanium alloys have great applications in the fields of medical devices, orthopedic implants and aerospace components due to their excellent physicochemical properties, and endowing their surface with superhydrophobic properties is very necessary. Inspired by the wax crystals of Nepenthes, superhydrophobic microstructures on titanium alloy were designed and then fabricated via femtosecond laser ablation and chemical fluorination. This innovative method attributes a programmable laser micro-processing technique that realizes the facile fabrication of superhydrophobic microstructures with the advantages of simple design and multiple functions. The fabricated superhydrophobic surfaces achieved the contact angle of 163.45° and the sliding angle of 5.13°, and exhibited ultralow adhesion, good bouncing behaviors, excellent anti-icing capability and strong functional durability. Moreover, analyses based on experiment results demonstrated that the microstructure characteristics have a significant effect on the superhydrophobicity, and appropriate parameters can improve the superhydrophobic properties. Additionally, due to the insufficient accuracy and uncontrollability of femtosecond laser ablation, irregular pores resembled the wax crystals were fabricated which can cause the formation of stable air-film and accordingly enhances the superhydrophobicity, therefore becomes the crucial technique of this study. This study offers an innovative method for the fabrication of multi-functional superhydrophobic surfaces on titanium alloys, and promotes their applications in engineering fields.