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Design of Chemical Surface Treatment for Laser Textured Metal Alloy to Achieve Extreme Wetting Behavior
摘要： Extreme wetting activities of laser-textured metal alloys have received significant interest due to their superior performance in a wide range of commercial applications and fundamental research studies. Fundamentally, extreme wettability of structured metal alloys depends on both surface structure and surface chemistry. However, compared with the generation of physical topology on the surface, the role of surface chemistry is less explored for the laser texturing processes of metal alloys to tune the wettability. This work introduces a systematic design approach to modify the surface chemistry of laser textured metal alloys to achieve various extreme wettabilities, including superhydrophobicity/superoleophobicity, superhydrophilicity/superoleophilicity, and co-existence of superoleophobicity and superhydrophilicity. Microscale trenches are first created on the aluminum alloy 6061 surfaces by nanosecond pulse laser surface texturing. Subsequently, the textured surface is immersion-treated in several chemical solutions to attach target functional groups on the surface to achieve the final extreme wettability. Anchoring fluorinated groups (-CF2- and -CF3) with very low dispersive and non-dispersive surface energy leads to superoleophobicity and superhydrophobicity, resulting in repelling both water and diiodomethane. Attachment of polar nitrile (-C≡N) group with very high non-dispersive and high dispersive surface energy achieves superhydrophilicity and superoleophilicity by drawing water and diiodomethane molecules in the laser textured capillaries. At last, anchoring fluorinated groups (-CF2- and -CF3) and polar sodium carboxylate (-COONa) together lead to very low dispersive and very high non-dispersive surface energy components. It results in the co-existence of superoleophobicity and superhydrophilicity, where the treated surface attracts water but repels diiodomethane.
关键词： Design,chemical modification,laser texturing,superhydrophilicity,superoleophobicity,superhydrophobicity
更新于2025-09-23 15:21:01
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Roles of chemistry modification for laser textured metal alloys to achieve extreme surface wetting behaviors
摘要： Wetting behaviors of structured metal surfaces have received considerable attention due to the wide range of applications for commercial, industrial, and military uses as well as fundamental research interests. Due to its adaptability, precision, and ease of automation, laser-based texturing techniques are desirable platforms to create micro- and nano-structures, including laser-induced periodic surface structures, or hierarchical structures on a metal substrate. However, micro- and nanostructures alone often do not achieve the desired wettability. A subsequent surface chemistry modification method must be performed to attain target extreme wettability for laser textured metal substrates. This review aims to provide a systematic understanding of the interdependence of surface chemistry modification and physical surface structures formed during the laser-based surface engineering methods. The role of surface chemistry on top of the surface structures is presented to decide the final wetting scenario. Specifically, by controlling the surface chemistry of a laser textured surface, wetting can be modulated from extreme hydrophobicity to hydrophilicity, allowing freedom to achieve complex multi-wettability situations. In each section, we highlight the most fruitful approaches and underlying mechanisms to achieve a fitting combination of surface structures and surface chemistry. Durability and stability of the treatd surface is also discussed in corrosive and abrasive environments. Finally, challenges in current studies and prospects in future research directions of this rapidly developing field are also discussed. This review will provide a comprehensive guideline for the design of laser texturing methods and the fabrication of extreme wetting surfaces for metal alloys.
关键词： superhydrophilicity,superhydrophobicity,metal alloy,Laser surface texturing,chemistry modification,silane treatment
更新于2025-09-23 15:21:01
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Facile fabrication of super-hydrophilic porous graphene with ultra-fast spreading feature and capillary effect by direct laser writing
摘要： This study demonstrated a facile method to fabricate super-hydrophilic 3D porous graphene with high capillary force and ultra-fast spreading characteristic by direct laser writing on KMnO4-coated polyimide (PI) films. Highly oxidized laser-induced graphene (OLIG) was obtained with dominated sp2 carbon referring from Raman spectroscopy and X-ray diffraction. In addition, abundant oxygen functional groups and a 3D porous scaffold structure with foam-like flakes were produced based on the results of X-ray photoelectron pattern and scanning electron microscopy. OLIG showed ultra-fast spreading properties that water drops can spread completely within dozens of milliseconds. The morphology and chemical composition also render the new material with good capillary effect. The capillary rate-of-rise test with IR camera demonstrated that the wetted height of OLIG strip can reach around 16 mm within 5 minutes.
关键词： superhydrophilicity,porous graphene,laser writing,capillary effect,ultra-fast spreading surface
更新于2025-09-23 15:19:57
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Formation of periodic superhydrophilic microstructures by infrared nanosecond laser processing of single-crystal silicon
摘要： The evolution of the morphology and composition of the single-crystal silicon surface irradiated by infrared and visible nanosecond laser pulses is investigated as a function of processing parameters (laser fluence, irradiation spot size, the number of pulses, background gas pressure and composition). Two types of periodic surface microstructures are obtained with IR (1064 nm) laser pulses in a narrow fluence range of 3-6 J/cm2. At a relatively low number of laser pulses applied, a grid of cleavage cracks is produced within the irradiation spot along the crystal orientation. With further Si irradiation, periodic microhillocks are formed in the nodes of the crack grid. Silicon surface with such microhillocks exhibits superhydrophilic properties which are retained during prolonged storage in air. The cracks are produced in any environment (including vacuum) but the microhillocks are observed only in the presence of oxygen. No periodic structures were observed with visible (532 nm) laser pulses. Mechanisms of nanosecond laser-induced periodic microstructure formation on silicon are discussed.
关键词： oxidation,superhydrophilicity,silicon,periodic microstructures,Nanosecond laser ablation,damage threshold
更新于2025-09-23 15:19:57
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Hydrophilic surface modification of TiO2 to produce a highly sustainable photocatalyst for outdoor air purification
摘要： Recently, TiO2 photocatalysts have been applied in various ways for outdoor air purification. The main challenge with these applications is the stability of the photocatalysts, as the surface of TiO2 can be easily deactivated by contaminants found in outdoor environments. For example, it is difficult to remove oily contaminants with water once they are exposed to the photocatalyst surface since the hydrophilicity of TiO2 is not sufficiently high to allow for self-cleaning. In the present work, we modified the surface of commercial TiO2 nanoparticles to be more hydrophilic; this was done by coating them with a thin polydimethylsiloxane (PDMS) layer and applying a subsequent heat treatment under vacuum. The surface-modified TiO2 showed outstanding ability to repel oily contaminants deposited on its surface upon exposure to water droplets due to its superhydrophilic properties. Then, we evaluated the UV-light-driven photocatalytic activity of the surface-modified TiO2 for the decomposition of acetaldehyde. The surface-modified TiO2 showed photocatalytic activity for the decomposition of acetaldehyde that was comparable to that of bare TiO2. We show that our hydrophilic-surface-modified TiO2 has high potential for applications in outdoor air purification for an extended time period.
关键词： Air purification,Acetaldehyde,Photocatalysis,TiO2,Superhydrophilicity
更新于2025-09-19 17:15:36
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Conical microstructuring of titanium by reactive gas assisted laser texturing
摘要： Femtosecond laser micromachining is an important and flexible method to generate precisely targeted surfaces on various materials. On titanium, the laser structuring process strongly depends on the laser parameters. For example, an increasement of the pulse length and repetition rate favors melting processes instead of ablation and microstructuring. We report on an investigation of reactive halogens (iodine, bromine, chlorine) and halocarbons as additives to the laser structuring process of pure titanium and the common alloy Ti-6Al-4V with 0.75 ps laser pulses. The choice of the halogen allows control of whether solely the chemical composition or the surface microstructure should be altered. Bromine was found to be an efficient additive to generate homogeneous microstructures based on micropillars at convenient conditions (air, atmospheric pressure). The resulting surfaces have been characterised by thermal emission infrared photography, scanning electron microscopy, energy dispersive X-ray spectroscopy, reflective UV/Vis spectroscopy and contact angle measurements. The bromine/air processed titanium surfaces revealed superhydrophilicity, strongly increased thermal emissivity and a high absorptivity (“black metal”).
关键词： Superhydrophilicity,Reactive halogens,Absorptivity,Titanium,Femtosecond laser micromachining,Microstructuring,Thermal emissivity
更新于2025-09-16 10:30:52
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Femtosecond Laser-Produced Underwater “Superpolymphobic” Nanorippled Surfaces: Repelling Liquid Polymers in Water for Applications of Controlling Polymer Shape and Adhesion
摘要： A femtosecond (fs) laser-ablated surface that repels liquid polymer in water is reported in this paper. We define this phenomenon as the “superpolymphobicity”. Three-level microstructures (including microgrooves, micromountains/microholes between the microgrooves, and nanoripples on the whole surface) were directly created on the stainless steel surface via fs laser ablation. A liquid polydimethylsiloxane (PDMS) droplet on the textured surface had the contact angle of 156 ± 3° and contact angle hysteresis less than 4° in water, indicating excellent underwater superpolymphobicity of the fs laser-induced hierarchical microstructures. The contact between the resultant superhydrophilic hierarchical microstructures and the submerged liquid PDMS droplet is verified at the underwater Cassie state. The underwater superpolymphobicity enables to design the shape of cured PDMS and selectively avoid the adhesion at the PDMS/substrate interface, different from the previously reported superwettabilities. As the examples, microlens array and microfluidics system were prepared based on the laser-induced underwater superpolymphobic microstructures.
关键词： superhydrophilicity,polymer repellence,three-level microstructure,femtosecond laser,underwater superpolymphobicity
更新于2025-09-12 10:27:22