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Prototyping of Superhydrophobic Surfaces from Structure-Tunable Micropillar Arrays Using Visible Light Photocuring
摘要： A new approach is reported to fabricate micropillar arrays on transparent surfaces by employing the light-induced self-writing technique. A periodic array of microscale optical beams is transmitted through a thin film of photo-crosslinking acrylate resin. Each beam undergoes self-lensing associated to photopolymerization-induced changes in the refractive index of the medium, which counters the beam’s natural tendency to diverge over space. As a result, a microscale pillar grows along each beam’s propagation path. Concurrent, parallel self-writing of micropillars leads to the prototyping of micropillar-based arrays, with the capability to precisely vary the pillar diameter and inter-spacing. The arrays are spray coated with a thin layer of polytetrafluoroethylene (PTFE) nanoparticles to create large-area superhydrophobic surfaces with water contact angles greater than 150° and low contact angle hysteresis. High transparency is achieved over the entire range of micropillar arrays explored. The arrays are also mechanically durable and robust against abrasion. This is a scalable, straightforward approach toward structure-tunable micropillar arrays for functional surfaces and anti-wetting applications.
关键词： light-induced self-writing,re-entrant,micropillars,hydrophobicity,nanoparticles
更新于2025-10-24 16:36:04
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Investigation of Strongly Hydrophobic and Thick Porous Silicon Stain Films Properties
摘要： Porous silicon (PSi) structures with strong hydrophobicity have been achieved by chemical etching of p-type silicon substrates in a solution based on hydrofluoric acid solution (HF) and vanadium oxide (V2O5). The surface morphology and microstructure of the elaborated structured silicon surfaces were investigated using Scanning Electron Microscope (SEM), contact angle and Fourier Transform Infrared spectroscopy (FTIR). The results show that the obtained structures exhibit hierarchically porous surfaces with porous pillars of silicon (PPSi) and an important hydrophobicity of the surface. The electrical properties of those PPSi structures were investigated in presence of 10 ppm of NO2 gas. The response time was about 30s at room temperature. Our results demonstrate that PPSi/Si are highly hydrophobic for long time and suitable for applications in the field of self-cleaning and may be a good candidate in elaborating practical NO2 sensors.
关键词： Porous silicon,Hydrophobicity,Gas sensing applications,Pillars structures
更新于2025-09-23 15:23:52
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Photoactive and hydrophobic nano-ZnO/poly(alkyl siloxane) coating for the protection of sandstone
摘要： Poly(alkyl siloxane) containing photoactive nano-ZnO (0.5 wt%) has been studied as a protective coating of glauconitic sandstone. Effect on visual appearance, hydrophobicity, porosity, water absorption/evaporation, and self-cleaning ability of the sandstone was measured. The results were evaluated in comparison with uncoated and poly(alkyl siloxane)-coated sandstone. Static contact angle of water reached 89° ± 3° and 128° ± 2° for poly(alkyl siloxane) and nano-ZnO/poly(alkyl siloxane) coating, respectively. Poly(alkyl siloxane) and nano-ZnO/poly(alkyl siloxane) coatings led to increased reduction in water absorption (>50%) for ≥18 h and ≥8 h, respectively, compared to the uncoated sandstone. The shorter time is compensated by self-cleaning ability: photodegradation of methylene blue on the nano-ZnO/poly(alkyl siloxane) coating after 5 h of UV irradiation was observed. This coating is a promising candidate for practical use in sandstone monuments protection.
关键词： Sandstone,ZnO,Photoactivity,Protection,Poly(alkyl siloxane),Hydrophobicity
更新于2025-09-23 15:23:52
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Synthesis and characterization of nanofiber-type hydrophobic organic materials as electrodes for improved performance of PVDF-based piezoelectric nanogenerators
摘要： Poly(3,4-ethylenedioxythiophene) (PEDOT) derivatives are synthesized by oxidative polymerization using sodium dodecyl sulfate (SDS) as an anionic surfactant dopant. The resulting polymeric materials featuring nanofiber-type one-dimensional (1D) structures are identified as poly(2-butyl-2,3-dihydrothieno[3,4-b][1,4]dioxine:dodecyl sulfate (PEDOT-C4:DS) and poly(2-hexyl-2,3-dihydrothieno[3,4-b][1,4]dioxine:dodecyl sulfate (PEDOT-C6:DS). The ratio of the DS anion doped into PEDOT-C4:DS and PEDOT-C6:DS is 0.16 and 0.23, respectively. The contact angle of water on the PEDOT-C4:DS and PEDOT-C6:DS films is 76.6° and 87.7°, respectively, showing hydrophobic properties similar to that with water on PVDF. It facilitated the fully uniform film formation due to excellent surface matching. Peeling force of PEDOT-C4:DS and PEDOT-C6:DS is stronger than the one of PEDOT:PSS-CNT composite. GIWAX analysis showed that PEDOT-C4:DS formed the highly ordered edge-on structure and PEDOT-C6:DS formed the bimodal orientation consisting of edge-on structure mainly and face-on structure slightly. The electrical conductivity (σPEDOT-C4:DS=50.0 S cm-1) of PEDOT-C4:DS is 41.7 times higher than that of PEDOT:PSS (σPEDOT:PSS=1.2 S cm-1). The output signals (maximum voltages/currents) of piezoelectric nanogenerators (PNGs, electrode/PVDF/electrode) using these materials as electrodes are PNG-1 (PEDOT:PSS-CNT composite) 1.25 V/128.5 nA, PNG-2 (PEDOT-C4:DS) 1.54 V/166.0 nA, and PNG-3 (PEDOT-C6:DS) 1.49 V/159.0 nA. Of these, PNG-2 & PNG-3 show maximum piezoelectric output power of 63.0 nW and 59.9 nW at 9 MΩ compared to PNG-1 (41.0 nW at 10 MΩ). They are enhanced up to 53.7%. The excellent surface matching between a piezoelectric active material and an electrode material leads to high output power.
关键词： 4-ethylenedioxythiophene) derivative,poly(3,nanofibrillar network,piezoelectric nanogenerator,nanofiber,hydrophobicity
更新于2025-09-23 15:23:52
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Highly Hydrophobic Conducting Nanocomposites Based on a Fluoropolymer with Carbon Nanotubes
摘要： A procedure was suggested for preparing highly hydrophobic conducting coatings based on fluoropolymers with carbon nanotubes of two types: Taunit-MD and carbon nanotubes functionalized with alkyl groups. The surface resistance, contact angle, sliding angle, and surface roughness were measured; structural features of the nanocomposites were studied. The properties of the coatings obtained depend on the concentration and type of the carbon nanotubes used. Introduction of functionalized carbon nanotubes into a fluoropolymer matrix allows preparation of coatings with higher values of the sliding angle and electrical resistance. The contact angle and sliding angle depend on the surface roughness and structure in different fashions.
关键词： carbon nanotubes,electrical conductivity,surface roughness,hydrophobicity,nanocomposites
更新于2025-09-23 15:22:29
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"Two-in-One" Strategy of o-Amino and Aromatic Nitrogen in Biomimetic Metal-Organic Frameworks for Efficient CO2 Photoconversion
摘要： Visible-light driven photoconversion of CO2 into energy carriers is highly important to the natural carbon balance and sustainable development. Herein, we demonstrate the biological nucleobase adenine-dependent CO2 photoreduction performance in green biomimetic metal-organic frameworks. Photocatalytic results indicate that AD-MOF-2 exhibited a very high HCOOH production rate of 443.2 μmol g-1 h-1 in pure aqueous solution, which is more than two times higher than that of AD-MOF-1 (179.0 μmol hour?1 g?1) in acetonitrile solution. Significantly, experimental and theoretical evidences reveal that CO2 photoreduction reaction mainly takes place on biological adenine molecules by unique o-amino assisted active aromatic nitrogen atom rather than traditional metal center. This work not only serves as an important case study for the development of green biomimetic photocatalysts used for artificial photosynthesis, but also proposes a new catalytic strategy for efficient CO2 photoconversion.
关键词： photosensitivity,hydrophobicity,biomimetic catalysis,green MOFs,artificial photosynthesis
更新于2025-09-23 15:22:29
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Biomimetic Polyimide-Supported Cuprous Oxide Photocatalytic Film with Tunable Hydrophobicity, Improved Thermal Stability, and Photocatalytic Activity toward CO <sub/>2</sub> Reduction
摘要： Flexible and thermally stable polyimide (PI) ?lms containing a hierarchical surface structure were synthesized as substrates to support visible-light active cuprous oxide for photocatalytic reduction of carbon dioxide for the ?rst time. With the nanocasting technique, the surface structure on the leaves of Xanthosoma sagittifolium was successfully duplicated on PI ?lms. Followed by the ion-exchange process and adequate thermal treatment, cuprous oxide nanoparticles were successfully immobilized on the arti?cial PI leaves and exhibited the capability to photoreduce carbon dioxide into carbon monoxide under visible-light illumination. With the selection of biomimetic structures and adjustment of fabrication parameters, the hydrophobicity and optical absorption edge of the photocatalytic ?lm were tunable. An increase in hydrophobicity improved the yield of carbon monoxide. The introduction of a hierarchical structure on the surface and cuprous oxide within the matrix dramatically enhanced the thermal stability of the PI ?lm. The ?exible photocatalytic ?lm is a promising material for the applications requiring high mechanical and thermal stability, such as industrial ?ue-gas treatments.
关键词： Thermal Stability,CO2 Reduction,Hydrophobicity,Polyimide,Photocatalytic,Biomimetic,Cuprous Oxide
更新于2025-09-23 15:22:29
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Sol-gel coating of colloidal particles deposited glass surface pertinent to self-cleaning applications
摘要： A sol-gel coating using colloidal silica on a glass surface is carried out towards improving the self-cleaning properties. The optical transmittance and hydrophobic characteristics of the resulting coating are analyzed using analytical tools. Since the sol-gel coating reduces the optical transmittance of the glass samples, due to scattering and diffusion of the incident optical radiation at the coating surface, silicon oil (Sigma-Aldrich, 10 cSt) impregnation method is introduced to improve the optical transmittance. Silicon oil has good heat transfer characteristics, stable properties over range of temperatures, and optically transparent characteristics with refractive index of 1.4034. The resulting coated surface is tested in outdoor environments to examine the dust effect on the optical transmittance of the sol-gel coated and oil impregnated glass samples. It is found that deposition of 75 nm size silica particles on the glass surface modifies the texture height of the sol-gel coating, which in turn, improves the surface hydrophobicity. Sol-gel coating results in a web-type fully connected porous structures; in which case, agglomeration of the synthesized particles is responsible for the fully connected porous texture at the coating surface. The optical transmittance remains low for the sol-gel coated glass samples because of scattering and diffusion of the incident optical radiation at the coating surface. Silicon oil impregnation improves the optical transmittance of the sol-gel coated samples. The dust particles immerse into the oil film and reduce the optical transmittance of the oil impregnated samples in outdoor environments.
关键词： Sol-gel coating,Hydrophobicity,Silicon oil impregnation,Silica,Outdoor testing
更新于2025-09-23 15:21:21
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Investigation and Prediction on Regulation of Hydrophobicity of Polymethyl Methacrylate (PMMA) Surface by Femtosecond Laser Irradiation
摘要： This study presents the contact angle prediction model of a trapezoidal groove structure based on the laser irradiation on polymethyl methacrylate (PMMA). The trapezoidal groove structure was designed and proposed according to the characteristics of a femtosecond laser. First, the complete wetting model and incomplete wetting model which were compatible with the characteristics of the laser mechanism were constructed based on the Gibbs free energy and the structural parameters of the trapezoidal groove structure. Then, based on the contact angle prediction models constructed, the samples were divided into two groups according to the designed structural parameters, and the experimental investigations were carried out. The result demonstrated that the incomplete wetting prediction model was more in line with the actual situation. The convex width and the top edge length of spacing of the trapezoidal groove structure both affected the contact angle prediction results. From both the experimental contact angles and the contact angles predicted by the incomplete wetting model, it could be known that the contact angle reached 138.09° when the ratio of the convex width to the top edge length of spacing was 0.25, indicating that the smaller the ratio of the convex width to the top edge length of spacing, the better the hydrophobicity of PMMA.
关键词： femtosecond laser,trapezoidal groove structure,polymethyl methacrylate,hydrophobicity
更新于2025-09-23 15:21:01
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Preparation and photochromic behavior of spiropyran-containing fluorinated polyacrylate hydrophobic coatings
摘要： In this study, spiropyran (SP)-containing fluorinated polyacrylate (F-PA-SP) latex was prepared by emulsion polymerization using fluorinated and SP-based acrylic monomers as raw materials. FT-IR and 1H-NMR demonstrate that the F-PA-SP copolymer has been successfully synthesized, and DLS and TEM analyses indicate that the synthesized latex has presented a uniform particle size of approximately 200 nm. XPS, AFM and water contact angle (WCA) analysis were used to investigate the surface properties of the F-PA-SP coating and demonstrate that its hydrophobicity is enhanced by addition of a fluorinated acrylic monomer. The photochromic properties of the coating were investigated by UV-Vis spectroscopy, and the results reveal that the F-PA-SP coating possesses better photo-responsiveness, fatigue resistance, and photo-reversibility under UV/Vis irradiation than the coating prepared using fluorinated polyacrylate/SP blended latex. Moreover, the WCA of the F-PA-SP coating subjected to UV/Vis irradiation shows minimal changes and retains its excellent hydrophobicity. Finally, the F-PA-SP latex was applied to cellulosic paper, and the resulting photochromic paper exhibits outstanding reversible color changes and hydrophobicity.
关键词： emulsion polymerization,hydrophobicity,fluorinated polyacrylate,spiropyran,photochromic
更新于2025-09-23 15:21:01