Designing “Supermetalphobic” Surfaces that Greatly Repel Liquid Metal by Femtosecond Laser Processing: Does the Surface Chemistry or Microstructure Play a Crucial Role?

Abstract

It is demonstrated that the wettability of liquid metal (LM) on a substrate is very different from the water wettability. Superhydrophobic and superhydrophilic silicon and polydimethylsiloxane surfaces, respectively, are obtained by femtosecond laser processing and proper chemical modification. All of the structured surfaces have excellent LM repellence, that is, supermetalphobicity, in spite of superhydrophobicity or superhydrophilicity. The experimental comparison and contact model analysis reveal that surface microstructure actually plays a crucial role in endowing a surface with supermetalphobicity while surface chemistry has a little influence on the formation of supermetalphobicity, because the liquid/solid contact is replaced by a solid/solid contact mode for a LM droplet on a textured substrate. It is believed that the established principle for creating supermetalphobic surfaces will enable to accelerate the application progress of LM materials in flexible circuits and liquid robots.

Bioinspired Underwater Superoleophobic Microlens Array With Remarkable Oil-Repellent and Self-Cleaning Ability

“…The microlens structure and MLAs were successfully obtained utilizing femtosecond laser enhanced chemical isotropic etching process (Hao et al, 2012;Chen et al, 2020). The hierarchical micro/nano surface structures were also achieved via femtosecond laser direct writing which inspired numerous researchers to realize surfaces with superwettability (Zhang et al, 2012;Yong et al, 2013Yong et al, , 2020Yin et al, 2017;Duan et al, 2018;Bai et al, 2020;Wu et al, 2020). Here, we present a simple way to fabricate a novel anti-oil MLA on a glass substrate by femtosecond laser-induced chemical isotropic etching and selective direct laser ablation (DLA) processes, respectively.…”

Simple and Low-Cost Oil/Water Separation Based on the Underwater Superoleophobicity of the Existing Materials in Our Life or Nature

“…Surface wettability is mainly governed by the chemical composition and surface morphology of a solid substrate (Genzer and Efimenko, 2006 ; Wang and Jiang, 2007 ; Wen et al, 2017 ; Yong et al, 2017a , 2018a , 2020 ; Bai et al, 2020 ; Wu et al, 2020 ). The inherent hydrophilic chemical composition and the micro/nanoscale hierarchical rough structures play an important role in the formation of the in-air superhydrophilicity and underwater superoleophobicity for the filter paper and the zeolite layer.…”

Fabrication of Chalcogenide Glass Based Hexagonal Gapless Microlens Arrays via Combining Femtosecond Laser Assist Chemical Etching and Precision Glass Molding Processes

“…The mold can be used thousands of times over without mold repair, so the fabrication of ChG MLA starts from a hard and high-temperature-resistant concave mold, which is made by a highly efficient FLACE technique on a BK7 optical glass substrate. Femtosecond laser pulses (Libra-usp-he, Coherent) [42][43][44], with a central wavelength of 800 nm, pulse duration of 50 fs, repetition rate of 1 kHz and laser power of 5 mW, were used and focused by an objective lens, which had a numerical aperture of 0.5. The high peak intensity of moderately and tightly focused femtosecond laser pulses made this possible through nonlinear multiphoton, avalanche and Coulomb explosions producing permanent structural modifications within a couple of picoseconds.…”