Superhydrophobic Glass Research Articles

Preparation of superhydrophobic glass fiber and interfacially reinforced glass fiber/epoxy composites by grafting polysiloxane nanowires

Ethyltrichlorosilane used as precursor reacted with glass fiber (GF) surface. Then polysiloxane was functionalized onto GF surface to improve GF’s hydrophobicity and interfacial properties of GF reinforced composites. Fourier transform infrared spectroscopy (FTIR) confirmed the successful grafting of polysiloxane onto GF’s surface. Energy dispersive spectroscopy (EDS) characterized the variation of chemical composition of GF surface. Scanning electron microscopy (SEM) images showed that the polysiloxane was grafted onto GF’s surface uniformly and the surface roughness of GF was enhanced obviously. Static contact angle analysis (SCA) revealed the significant improvement of surface hydrophobicity. Compared with the original GF composites, the interfacial shear strength (IFSS) increased by 36.52%. Meanwhile, we discovered a facile way to accomplish the experiment.

Durable and robust transparent superhydrophobic glass surfaces fabricated by a femtosecond laser with exceptional water repellency and thermostability

Self-cleaning transparent glass surfaces with periodic micro–nano structures fabricated by a femtosecond laser exhibit exceptional water repellency and thermostability.

Wettability control between superoleophobic and superoleophilic characteristics on the modified superhydrophobic surfaces treated with fluoroalkyl end-capped vinyltrimethoxysilane oligomeric silica/poly(styrene-co-butadiene) nanocomposites: application to the separation of oil and water

Fluoroalkyl end-capped vinyltrimethoxysilane oligomer [RF-(CH2CHSi(OMe)3) n -RF; RF = CF(CF3)OC3F7; n = 2, 3: RF-(VM) n -RF] can undergo the sol–gel reaction in the presence of poly(styrene-co-butadiene) (SBR) under alkaline or acidic conditions, respectively, to afford the corresponding fluorinated oligomeric silica/SBR nanocomposites [RF-(VM-SiO2) n -RF/SBR]. Wettability control between superoleophobic and superoleophilic characteristics was observed on the modified superhydrophobic glass surfaces treated with these fluorinated nanocomposites. The nanocomposites, which were prepared under alkaline conditions, can provide a superoleophobic/superhydrophobic (superamphiphobic) characteristic on the modified surface; however, a superoleophilic/superhydrophobic characteristic was observed on the modified surface treated with the fluorinated nanocomposites, which were prepared under acidic conditions. Interestingly, the fluorinated nanocomposite particle powders possessing a superoleophilic/superhydrophobic characteristic were applied to the packing material for the column chromatography to separate not only the mixture of oil and water but also the W/O emulsion to isolate the transparent colorless oil. In addition, these particle powders were found to have a good reusability as the packing materials for the separation of the mixture of oil and water.

Improved super-hydrophobicity of eco-friendly coating from palm oil fuel ash (POFA) waste

Considerable efforts have been made for the fabrication of super-hydrophobic coating for self-cleaning applications. However, a facile, eco-friendly and cost effective coating technology is still a challenging issue. In this present work, a super-hydrophobic glass surface was fabricated using palm oil fuel ash (POFA) waste as silica source and non-fluoro polydimethylsiloxane (PDMS) as surface functionalizing agent. A simple spraying technology was used to coat the super-hydrophobic solution on the glass substrate. POFA was analyzed using XRF, XRD and FT-IR spectroscopy techniques. The super-hydrophobic glass substrates were characterized via FT-IR, FE-SEM, AFM, UV–vis and water contact angle (WCA) analysis. The weight ratio of PDMS to silica solution (SS) (1:0, 1:1, 1:2, 1:3, 1:4, 1:5) on the super-hydrophobicity was studied in detail. A water contact angle (WCA) of 156±1° was achieved when coating the glass substrate with PDMS: SS (1:2). The stability of the coating was evaluated via pH test and UV irradiation experiment, respectively. The results revealed that PDMS:SS (1:2) coated glass substrate is stable and durable in acid-base environment. Upon UV aging, WCA of PDMS:SS (1:2) was greatly improved to 171±2°.

Condensed microdrops self-jumping based on flake-like nanostructures on a glass slide

Condensed microdrops self-jumping (CMSJ) surfaces with specific nanostructure have been actively explored to promote favorable droplet dynamics for enhancement of condensation heat transfer efficiency. However, the CMSJ surfaces based on the glass itself are insufficient in the past, although it is significant in daily life and industry processes. Here, we report condensed microdrops with size of 20–30 μm could continuously self-jumping on the superhydrophobic glass slide with flake-like nanostructures and over 75% of dewdrops were maintained their diameter below 20 μm after condensed 1000 s. This work is expected to provide unique advantages in condensation heat transfer for enlargement of application of glass in various fields.

Green Fabrication of Transparent Superhydrophobic Coatings via One-pot Method

A fluorine-free and transparent superhydrophobic coating was fabricated via a simple method. The coated glass exhibited excellent superhydrophobicity with water contact angle (WCA) about 156° and sliding angle (SA) about 3°. In addition, the as-prepared superhydrophobic glass also showed great transparency and self-cleaning properties. The superhydrophobic polydopamine@SiO2 (PDA@SiO2) coating can be also applied on other substrate surfaces through a spray-coating approach. Moreover, a sponge coated by the superhydrophobic coating can be used to absorb oil from water.

Effects of surface nanostructures on self-cleaning and anti-fogging characteristics of transparent glass

Nanostructured transparent glass surfaces with self-cleaning and anti-fogging properties were fabricated using a non-lithographic, anisotropic etching technique. The superhydrophilic glass surface was achieved by nanostructuring pre-deposited SiO2 film in a glow discharge chamber. For superhydrophobicity, the surface energy of the nanostructured glass was lowered by treatment with 1H,1H,2H,2H-perfluorooctyl trichlorosilane. The self-cleaning and anti-fogging behavior was compared for glasses with different wettabilities by measuring the optical transmittance as well as the surface morphology and contact angles. In measuring the anti-fogging behavior, we included the effects of air flow impinging on the glass surface to emulate many practical situations. The superhydrophobic glass was superior to the superhydrophilic glass when considering both the self-cleaning and anti-fogging behavior with durability, particularly under air flow. The work can be used to fabricate transparent glass products for which minimizing surface contamination is crucial, e.g., eyeglasses, solar cells, and optical instruments.

Improved Hydrophobicity of Silicon Dioxide Integrated Zinc-Tellurite Glass Surface

Economically viable and maintenance free glass surfaces with improved hydrophobicity are highly demanding in the recent nanotechnology era. Deposition of pollutants and dirt on glass surface that not only causes visual obscurity but also damages the cultural heritages are still to be researched intensely. It is documented that excellent hydrophobic surfaces (with contact angle greater than 90o) can be achieved by controlling the surface wettability, where liquid droplets remain spherical on such surfaces. Selection of materials and the preparation method play a significant role towards such accomplishments. Stirred by this idea, we explored the feasibility of fabricating super-hydrophobic tellurite glass systems by facilely varying the compositions of different constituents. Highly transparent and thermally stable ternary tellurite glass system with chemical composition of (80-x)TeO2 – xSiO2 – 20ZnO, where x = 0.00 to 0.20 mol% are synthesized via conventional melt-quenching method. Samples are characterized using Atomic Force Microscopy (AFM) and contact angle measurements. The impact of SiO2 concentrations variation on the surface roughness, surface energy, and hydrophobic properties are inspected. Glass surface roughness as much as 9.885 nm is attained. The optimal value of water contact angle is discerned to be 101.02° for 0.1 mol% of SiO2 incorporation into the amorphous tellurite host matrix. Besides, the surface energy revealed an inverse proportionality to the water contact angle. This achieved contact angle (greater than 90°) makes this hydrophobic glass surface beneficial for diverse applications. It is established that the present glass composition may be prospective for the development of super-hydrophobic surfaces.

Transparent superhydrophobic solar glass prepared by fabricating groove-shaped arrays on the surface

In this paper, we fabricate superhydrophobic solar glass by microstructuring of the surface using picosecond laser pulses and then coating the surface with a layer of fluoroalkylsilane molecules. The glass surface shows the hierarchical structures containing both micro- and nanoscale roughness after laser irradiation. The increase in glass surface roughness makes the surface exhibit superhydrophilicity with a water contact angle of 0°. After surface modification with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, the glass surface exhibits stable superhydrophobicity. By varying the laser line intervals, we can regulate the surface morphology and the wetting properties. With the increase of laser line interval, the contact angles of the glass surfaces range from 172°±1° to 156°±2° and the sliding angles can be ignored. Before chemical surface modification, we also find that the glass surface of hierarchical structures is superoleophobic underwater. The contact angle for chloroform is 163°±2° and the sliding angle is 1.5°±0.4°. In addition, the as-prepared glass surface shows excellent transparency and its average transmittance is up to 87.28% in the visible spectrum. Furthermore, we find that the water droplet on the modified original glass surface looks like a lens which has zoom function.

Self-assembled monolayer of functionalized silica microparticles for self-cleaning applications

Development of durable superhydrophobic glass surfaces with excellent self-cleaning property has raised tremendous interest in materials science. In this study, superhydrophobic coatings were prepared on glass substrates by octadecyltrichlorosilane modified silica microparticles using dip-coating technique. The coating shows the superhydrophobicity with water static contact angle of 165.5°±5.7° and sliding angle of 2.0°±0.5°. Surface morphology analysis reveals the presence of non-spherical microstructures on the coated surface. Coating exhibits excellent self-cleaning property. Additionally, coating withstands its superhydrophobicity after undergoing 4 cycles of abrasion and 30 cycles of adhesion tests. Superhydrophobicity remains unaffected after annealing the sample at temperatures ranging from 40 to 160°C. It also maintains its superhydrophobicity when immersed in different pH solutions. Further, impact behavior of water droplet on the coating surface was also studied. This facile method of preparing superhydrophobic glass surface is advantageous for various industrial applications as it can be used to make superhydrophobic glass surface of any size and shape.

‘Click’ polymer of carbon nanotubes for superhydrophobic glass and leather

Copper (I)-catalyzed 1,3-dipolar cycloaddition reaction of azide–alkyne is called a ‘click’ reaction. It is an adaptable tool for preparing multifunctional materials. In this paper, the authors report click polymerization of single-walled carbon nanotubes (SWCNTs) with thiophene/aryl compounds and their electronic/spectroscopic properties and applications. The various spectroscopic and microscopic studies (Fourier transform infrared (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, nuclear magnetic resonance and ultraviolet–visible) confirmed the success of the polymerization. The superhydrophobicity of the materials was studied by contact angle measurement. The FT-IR studies indicated the disappearance of azide residues in the polymeric products, and the Raman studies exhibited a high degree of covalent functionalization of SWCNTs. The XPS data show the presence of polymeric elements in the click copolymer of SWCNTs. Dynamic light scattering studies confirmed the broad size distribution of the materials. Moreover, the thermogravimetric analysis revealed the high thermal stability of the polymer. Finally, wettability measurements of leather and glass surfaces after coating with the copolymer of SWCNTs show high water contact angles of 155 and 163°, respectively. The results were well reproduced, and these superhydrophobic characteristics indicate the material’s efficiency for designing various superhydrophobic surfaces.

Transparent alumina based superhydrophobic self–cleaning coatings for solar cell cover glass applications

Superhydrophobic surfaces based on aluminium oxide coatings had been developed on glass substrates via solution based approach for solar panel cover glass applications. The fabricated surface was amorphous with an interconnected porous network of nanoflakes. The static contact angle of the prepared coatings was 161° and exhibited superior self–cleaning behaviour at a tilting angle less than 10°. The 300nm thick coating with refractive index value gradually decreased from air (n −1), through the fabricated coating (n −1.35) towards the glass substrate (n – 1.56) enabled it to acquire a high average transmittance of 95% with anti-reflecting property. The photovoltaic performance of commercially available solar cells covered with uncoated glass substrate and aluminium oxide coated glass substrate was measured under various conditions (such as – fabricated, artificially contaminated and self – cleaned conditions) and the results were compared. The uncoated glass substrate and aluminium oxide coated superhydrophobic glass substrate recovered the efficiency of saw dust contaminated solar panel by 67% and 91%, respectively, thereby enabling the fabricated superhydrophobic glass substrate to be effectively useful for self–cleaning cover glass applications.

Fabrication of transparent superhydrophobic glass with fibered-silica network

In this paper, silica was deposited on the soot film pre-coated glass via chemical vapor deposition. Through calcination at 500°C with the assistance of O2 airflow, the soot film was removed and a novel robust fibered-silica network film was then decorated onto the glass substrate. After modification with fluorosilane, the surface water contact angle (WCA) was 166° and sliding angle (SA) was 1° which behaves a good self-cleaning for the as-prepared glass. And its average transmittance was still over 88% in visible wavelength. Moreover, this fibered-silica coating showed a strong tolerance for heavy water droplets, acid/alkali corrosion, salt solution immersion and thermal treatment.

Thermoplastic forming of bulk metallic glasses

The viscosities of metallic glasses gradually drop with temperature rising in their supercooled liquid region (SLR) which enables them to be thermoplastically formed and totally overturns the processing method of traditional metallic materials: their forming can be realized under temperature and stress far below those of traditional metallic materials. Based on this property, metallic glasses are considered as the ideal miniature fabrication materials due to their unique amorphous structures and no crystalline defects such as dislocation and grain boundary.The thermoplastic micro forming of metallic glasses in their SLR is studied in the present paper. A universal equation which describes the filling kinetics of viscous metallic glasses in the non-circular channel is proposed with the help of fluidic mechanics, and the results may be theoretically useful for the micro application of metallic glasses.In addition, some applications in the micro thermoplastic forming of metallic glasses are introduced. A metallic glass mold insert for hot embossing of polymers is fabricated by the micro thermoplastic forming of metallic glass, and it is found to have many advantages in mechanical property, fabrication efficiency, surface quality, etc. compared with the traditional material and method. A similar approach is used to fabricate gratings, which may provide a new material and technology to produce gratings. The superhydrophobic metallic glass surface with excellent abrasion and corrosion resistance is also fabricated by constructing micro-nano hierarchical structures on metallic glass surface. The bulk metallic glass micro fuel cell is also finished and found to have good performance.

Fabrication of Slippery Lubricant-Infused Porous Surface with High Underwater Transparency for the Control of Marine Biofouling.

Marine optical instruments are bearing serious biofouling problem, which affects the accuracy of data collected. To solve the biofouling problem of marine optical instruments, a novel instance of slippery lubricant-infused porous surface (SLIPS) with high underwater-transparency was designed over glass substrate via infusing lubricant into its porous microstructure fabricated with hydrothermal method. The advantage of SLIPS as antibiofouling strategy to marine optical instruments was proven by comparing its underwater optical and antibiofouling performances with three kinds of samples (hydrophilic glass sample, textured hydrophilic glass sample, and superhydrophobic glass sample). The modification of SLIPS enhances the underwater-transparency of glass sample within the wavelength of 500-800 nm, for the infusion of lubricant with lower refractive index than glass substrate. In contrast with hydrophilic surface, textured hydrophilic surface and superhydrophobic surface, SLIPS can significantly inhibit bacterial and algal settlements, thereby maintaining high underwater-transparency in both dynamic and static seawater. The inhibition of bacterial and algal settlements over SLIPS results from its liquid-like property. The contact angle hysteresis of water over SLIPS increases with immersion time in seawater under different conditions (static, dynamic, and vibration conditions). Both dynamic and vibration conditions accelerate the failure of SLIPS exposed in seawater. This research provides valuable information for solving biofouling problem of marine optical instruments with SLIPS.

Fabrication of “petal effect” surfaces by femtosecond laser-induced forward transfer

Superhydrophobic adhesive glass surfaces with polystyrene has been obtained via femtosecond laser induced forward transfer (LIFT). Using this facile method, we obtained composite structures on the glass surface, achieving the transformation from hydrophilicity to superhydrophobicity with contact angle from 36.22° on the glass surface to 159.19° on the LIFT modified glass surface. Analogous to the “petal effect”, the obtained superhydrophobic surface also shows high adhesion. Furthermore, the wettability of LIFT modified glass surface can be tuned by changing the interval width of laser scanning, which can be explained by the Cassie impregnating wetting model.

A novel method for the fabrication of superhydrophobic nylon net

In this study, we demonstrate a facile, cost-effective, and scalable method to fabricate superhydrophobic nylon net surface based on textured adhesive coating in combination with hydrophobization. The nylon net was immersed into an N-Methyl-2-pyrrolodone solution containing one-component polyurethane adhesive and then directly transferred into a glycerol aqueous solution to form a textured adhesive coating spontaneously. The silanization was further achieved through polar groups on the adhesive coating with alkylsilane compounds, forming self-assembled monolayers on the surface of nylon net. This resulted in our ability to tune the surface properties of the nylon net from being hydrophilic (18°) to superhydrophobic. The silanized adhesive coating endowed the nylon net with a water contact angle of 152° and a sliding angle less than 5°. When applied to oil-water separation, the superhydrophobic nylon mesh maintained its water repellency even after 60 cycles of oil-water separation and the separation efficiency (n-hexane) was over 95%. The method developed was also successfully applied to construct superhydrophobic filter paper, fiberglass cloth and glass slide. Moreover, this method can be simplified when applied to construct superhydrophobic filter paper. Therefore, this cost-effective, easily-operated and environment friendly method offers great technological promise in the field of constructing superhydrophobic coatings on a large scale.

The super-hydrophobic IR-reflectivity TiO2 coated hollow glass microspheres synthesized by soft-chemistry method

The super-hydrophobic and IR-reflectivity hollow glass microspheres (HGM) was synthesized by being coated with anatase TiO2 and a super-hydrophobic material. The super-hydrophobic self-cleaning property prolong the life time of the IR reflectivity. TBT and PFOTES were firstly applied and hydrolyzed on HGM and then underwent hydrothermal reaction to synthesis anatase TiO2 film. For comparison, the PFOTES/TiO2 mutual-coated HGM (MCHGM), PFOTES single-coated HGM (F-SCHGM) and TiO2 single-coated HGM (Ti-SCHGM) were synthesized as well. The MCHGM had bigger contact angle (153°) but smaller sliding angle (16°) than F-SCHGM (contact angle: 141.2°; sliding angle: 67°). Ti-SCHGM and MCHGM both showed similar IR reflectivity with ca. 5.8% increase compared with original HGM and F-SCHGM. For the thermal conductivity, coefficients of F-SCHGM (0.0479W/(mK)) was basically equal to that of the original HGM (0.0475W/(mK)). Negligible difference was found between the thermal conductivity coefficients of MCHGM-coated HGM (0.0543W/(mK)) and Ti-SCHGM (0.0546W/(mK)).

A self-modification approach toward transparent superhydrophobic glass for rainproofing and superhydrophobic fiberglass mesh for oil⿿water separation

A method employing one kind of material both for the construction of rough morphology and the chemical modification is called self-modification by us, which has not been reported in fabricating superhydrophobic surfaces so far. In this paper, taking candle soot as an intermediate, we created rough, superhydrophilic and transparent surfaces on glass trough calcination of polydimethylsiloxane (PDMS) at 550°C. Subsequently, a novel chemical vapour deposition (CVD) modification was conducted by heating PDMS at 330°C in air to give the surfaces a water contact angle (WCA) of 170°±0.5° and a sliding angle (SA) of 0°. This CVD modification is expected to be a valuable way of modification because of its simple operation, low cost and short time consumption. Results indicate that the high temperature calcination and the moderate temperature CVD modification can drastically improve the stability of the surperhydrophobic surfaces through controlling the morphology and the surface chemical composition. The as-prepared glass surfaces are capable of bearing heavy rains, keeping the sight clear in the rain and being used at a high temperature (<400°C) or in water. Besides, superhydrophobic fiberglass mesh was prepared and applied in oil⿿water separation.

One-step spraying to fabricate nonfluorinated superhydrophobic coatings with high transparency

Designing multifunctional and fluorinate-free liquid-repellent materials via a facile and scalable method is highly desired. Herein, a transparent, durable, and self-cleaning superhydrophobic coating based on trimethoxypropylsilane-silica nanoparticles sol solution was prepared by one-step process. Once spray deposited on glass substrates, the transparent superhydrophobic self-cleaning glass with high water contact angle (158.5°) as well as low sliding angle (3.9°) was obtained. The transmittance of coated glass substrates is above 80 % in visible-light region (400–800 nm). Moreover, the prepared coatings kept stable superhydrophobicity under extreme environment conditions of high temperature and humidity, high or low temperature, and UV light irradiation. Water droplets could still roll off the obtained surface easily after examined by water impact and lacerating the surface with a knife. In addition, this versatile and environmentally benign approach can be applied on wide substrates readily by using spraying or dipping technique without any extra surface treatments. Therefore, our method may provide extensive applications in optoelectronics, liquid-repellent coatings, and oil–water separation.