Sandpaper Abrasion Test Research Articles

Facile fabrication of durable superhydrophobic silica/epoxy resin coatings with compatible transparency and stability

It is a practical route for taking advantage of the high binding force of epoxy resin to fabricate mechanically robust superhydrophobic surfaces. However, this kind of superhydrophobic surfaces is hard to be endowed with high transparency. Here, we developed transparent and durable superhydrophobic bilayer coatings containing hydrophobic silica particles on top and an epoxy resin bonding layer at the base via a simple approach with common apparatus and reagents. The transmittance of the coated glass at 550 nm is as high as 90.3%, close to the transmittance of 91.8% for the bare glass. The stabilities of these coatings were tested by sandpaper abrasion tests, simulated seawater immersion and heat treatment experiments. The results demonstrate the as-prepared superhydrophobic coatings have excellent self-cleaning ability, good mechanical strength, high chemical and thermal stabilities. Additionally, the method presented here can effectively reach a proper balance between high transparency and excellent durability. The self-cleaning superhydrophobic coatings are independent of the nature of the substrates and have great application potential in industry and real-life.

An all-water-based system for robust superhydrophobic surfaces

Superhydrophobic surfaces with micro-/nanohierarchical structures are mechanically weak. Generally, organic solvents are used to dissolve or disperse organic adhesives and modifiers to enhance the mechanical strength of superhydrophobic surfaces. In this work, an all-water-based spraying solution is developed for the preparation of robust superhydrophobic surfaces, which contains ZnO nanoparticles, aluminum phosphate as an inorganic adhesive, and polytetrafluoroethylene with low surface energy. The all-water-based system is appreciated for low price and less pollution. Importantly, the prepared superhydrophobic surfaces are durable enough against various harsh conditions (such as UV irradiation for 12 h, pH values from 1 to 13, and temperatures from −10 to 300 °C for 12 h) and physical damages (including sandpaper abrasion and sand impact tests for 50 cycles). In addition, the obtained interfacial materials show promise for practical applications such as anti-icing and oil-water separation.

Transforming a Simple Commercial Glue into Highly Robust Superhydrophobic Surfaces via Aerosol-Assisted Chemical Vapor Deposition.

Robust superhydrophobic surfaces were synthesized as composites of the widely commercially available adhesives epoxy resin (EP) and polydimethylsiloxane (PDMS). The EP layer provided a strongly adhered micro/nanoscale structure on the substrates, while the PDMS was used as a post-treatment to lower the surface energy. In this study, the depositions of EP films were taken at a range of temperatures, deposition times, and substrates via aerosol-assisted chemical vapor deposition (AACVD). A novel dynamic deposition temperature approach was developed to create multiple-layered periodic micro/nanostructures that significantly improved the surface mechanical durability. Water droplet contact angles (CA) of 160° were observed with droplet sliding angles (SA) frequently <1°. A rigorous sandpaper abrasion test demonstrated retention of superhydrophobic properties and superior robustness therein, while wear, anticorrosion (pH = 1-14, 72 h), and UV testing (365 nm, 3.7 mW/cm2, 120 h) were carried out to exhibit the environmental stability of the films. Self-cleaning behavior was demonstrated in clearing the surfaces of various contaminating powders and aqueous dyes. This facile and flexible method for fabricating highly durable superhydrophobic polymer films points to a promising future for AACVD in their scalable and low-cost production.

Rational Design and Construction of Well-Organized Macro-Mesoporous SiO2/TiO2 Nanostructure toward Robust High-Performance Self-Cleaning Antireflective Thin Films

Antireflection (AR) thin films on optical substrates are of great significance in high-performance optoelectronic devices. Here, we present a rational design and construction of well-organized macro-mesoporous nanostructure toward robust high-performance self-cleaning antireflective thin films on the basis of effective medium theory and finite difference time domain (FDTD) simulations that combine the optical design principle. A hierarchical macro-mesoporous SiO2 thin film with very high porosity and gradient refractive indexes works as a λ/4-wavelength AR layer and significantly suppresses the reflection in the range from 350 to 1200 nm. Even after dip-coating a layer of high refractive index TiO2 nanocrystals, the nanostructured thin film still exhibits broadband AR properties which are much superior to conventional flat SiO2/TiO2 thin films, especially in the range of 350-500 nm. In addition, the obtained thin film exhibits photocatalytic self-cleaning and durable superhydrophilicity. The advantages brought by the well-organized macro-mesoporous structure are also testified through comparing to the solely mesoporous SiO2/TiO2 film counterpart. Moreover, the pencil hardness test and sandpaper abrasion test show favorable robustness and functional durability of the thin film, which make it extremely attractive for practical applications in optical devices, display devices, and photovoltaic cells.

Rough Structure of Electrodeposition as a Template for an Ultrarobust Self-Cleaning Surface.

Superhydrophobic surfaces with self-cleaning properties have been developed based on roughness on the micro- and nanometer scales and low-energy surfaces. However, such surfaces are fragile and stop functioning when exposed to oil. Addressing these challenges, here we show an ultrarobust self-cleaning surface fabricated by a process of metal electrodeposition of a rough structure that is subsequently coated with fluorinated metal-oxide nanoparticles. Scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction were employed to characterize the surfaces. The micro- and nanoscale roughness jointly with the low surface energy imparted by the fluorinated nanoparticles yielded surfaces with water contact angle of 164.1° and a sliding angle of 3.2°. Most interestingly, the surface exhibits fascinating mechanical stability after finger-wipe, knife-scratch, sand abrasion, and sandpaper abrasion tests. It is found that the surface with superamphiphobic properties has excellent repellency toward common corrosive liquids and low-surface-energy substances. Amazingly, the surface exhibited excellent self-cleaning ability and remained intact even after its top layer was exposed to 50 abrasion cycles with sandpaper and oil contamination. It is believed that this simple, unique, and practical method can provide new approaches for effectively solving the stability issue of superhydrophobic surfaces and could extend to a variety of metallic materials.

Novel mussel-inspired Ti-6Al-4V surfaces with biocompatibility, blood ultra-drag reduction and superior durability

In order to develop new Ti-based biomaterials with biocompatibility, blood ultra-drag reduction and superior durability, a novel fabrication combining simple electrochemical and chemical processes was proposed. After being modified by C14H19F13O3Si (FAS), a biocompatible TiO2-SiO2-polydopamine composite surface on Ti-6Al-4V substrate was obtained. The biocompatibility was evaluated using a series of in vitro test, revealing that compared with Ti-6Al-4V alloys, the surfaces exhibited a number of bio-advantages such as anti-platelet aggregation, anti-bovine serum albumin protein adsorption, a lower hemolysis rate (~0.7%) and non-cytotoxicity (the cell viability >88%). The test of human microvascular endothelial cells (HMEC) cultured on the specimens for 48h showed better cell proliferation of the surface. Moreover, we explored the blood dynamic characteristics of titanium alloy substrate biomaterial for the first time, with a focus on the effects of dopamine-reactant concentration on blood flow resistance. The results showed that, compared to titanium alloy material, the TiO2-SiO2 surface modified by 4mg·mL−1 dopamine solution displayed the optimal blood drag reduction characteristics, reaching a 76% drag reduction. After a 2m (800 meshes, 3500Pa) sandpaper abrasion test, the surface still maintained a superior repellency of blood (contact angles>150°, sliding angles<10°). This practical method may expand the applications of biomedical implantation materials.

Fabrication of recyclable and durable superhydrophobic materials with wear/corrosion-resistance properties from kaolin and polyvinylchloride

In this study, mechanically stable and recyclable superhydrophobic materials were prepared from polyvinylchloride (PVC) and kaolin nanoparticles modified by stearic acid using a simple and low-cost drop-coating. The obtained materials displayed liquid-repellent toward water and several other liquids of daily life (such as orange juice, coffee, milk, coca cola and ink). These superhydrophobic materials showed remarkable robustness against sandpaper abrasion, UV-irradiation and ultrasonication test, while retaining its superhydrophobicity even after 60 abrasion cycles loaded of 500g with sandpaper, 7days UV-irradiation or 120min ultrasonication test. The excellent durability against complex conditions was attributed to the hierarchical structure and strong interfacial adhesion of the materials. More significantly, the materials used in the coating could be recycled and reconstructed without losing its superhydrophobicity. The current superhydrophobic materials tolerate rigorous environment, opening a new avenue to a variety of practical applications.

Fabrication method of large-scale and mechanically durable superhydrophobic silicon rubber/aerogel coating on fibrous substrates

We report on a simple and large-scale method for the fabrication of mechanically durable superhydrophobic coatings via electrostatic powder spray of aerogel micro particles on the fibrous substrates. The coatings are obtained by dip-coating fibrous substrates in silicon rubber/toluene solution, followed by the electrostatic spray of aerogel micro particles on the samples. The method is applicable to a large number of fibrous substrates with different pore sizes. Depending on the silicon rubber solution concentration, it is possible to obtain surfaces with hierarchical morphology. The wetting behavior dependent on the concentration of silicon rubber/toluene solution can provide coatings with static water contact angles (160°–168°) and sliding angles (3°–21°). Fibrous surfaces obtained were characterized by scanning electron microscopy and static water contact angle measurement. Also, mechanical durability of the surfaces was examined using high pressure airflow, sandpaper abrasion test, and water static pressure.

Fabrication of self-cleaning super-hydrophobic nickel/graphene hybrid film with improved corrosion resistance on mild steel

A self-cleaning super-hydrophobic nickel/graphene hybrid film with hierarchical structure was successfully fabricated on mild steel (MS) by electro-deposition process followed by myristic acid modification. The surface morphology and composition were characterized by a field emission scanning electron microscope (FESEM) and attached energy dispersive X-ray spectrum (EDS). The results showed that the hierarchical nickel/graphene film was well formed with random pinecone-like nano-protrusions nickel array on every micro-graphene-protrusion. The super-hydrophobic surface exhibited excellent super-hydrophobicity with a static water contact angle (CA) as high as 160.4±1.5° and a sliding angle (SA) as low as 4.0±0.9°. The super-hydrophobic surface showed excellent anticorrosion performance, mechanical durability and long-term stability in 3.5wt.% NaCl solution, which were characterized by electrochemical impedance spectroscopy (EIS), sandpaper abrasion and immersion tests. In addition, the super-hydrophobic surface also exhibited good self-cleaning performance.

Spray-coated superhydrophobic surfaces with wear-resistance, drag-reduction and anti-corrosion properties

This paper proposes a facile and low-cost method of preparing superhydrophobic surfaces on aluminium substrates using a two-step spraying method. A layer of hydrocarbon resin adhesive was sprayed on the substrate, after which dichlorodimethylsilane-modified hydrophobic silica nanoparticles were sprayed on the adhesive primer. The surface morphology, wettability and chemical composition were characterized by scanning electron microscope, water contact angle meter and X-ray photoelectron spectroscopy, respectively. The water contact angle of the superhydrophobic surface reached 153.5°±1.5° and the sliding angle was 1.8°±0.2°. The surface exhibited good wear-resistance in sandpaper abrasion, finger-wiping and knife-scratching tests. Even if damaged, the surfaces could be easily repaired. Rheometry results showed that the surface drag reduction rate reached up to 48.7%. Dynamic polarization tests indicated a great improvement in anti-corrosion properties with a decrease of two orders of magnitude in the corrosion current. The present method can be easily expanded to other materials and does not require special conditions, advanced equipment or complicated preparation processes, making it suitable for mass production.

Robust coating with superhydrophobic and self-cleaning properties in either air or oil based on natural zeolite

Abstract We have developed a facile and cost-effective method to fabricate superhydrophobic surfaces with self-cleaning properties in either air or oil environment. Firstly, a series of characterizations were conducted to show the reason why hydrophilic natural zeolite became hydrophobic. Then an ethanolic suspension of perfluorodecyltrichorosilane-coated natural zeolite was coated on both hard and soft substrates including glass and filter paper. Field emission scanning electron microscopy, atomic force microscopy and optical contact angle meter were used to characterize the morphology, roughness and wettability of the surface. The results showed that the coating had micro- and nanoscale hierarchical structures, which endowed the coating with excellent superhydrophobic and self-cleaning properties when exposed to either air or oil. Finally, when using double faced adhesive tape to bond the superhydrophobic coating to the glass, the coating remained superhydrophobicity after 30 cycles of sandpaper abrasion test. The robust superhydrophobic coating with self-cleaning properties in either air or oil may have a potential use as an equipment protective coating.

Brilliant Structurally Colored Films with Invariable Stop-Band and Enhanced Mechanical Robustness Inspired by the Cobbled Road.

Recently, structural colors have attracted great concentrations because the coloration is free from chemical- or photobleaching. However, the color saturation and mechanical robustness are generally competitive properties in the fabrication of PCs (photonic crystals) films. Besides, the structure of PCs and their derivatives are easy to be invaded by liquids and lead to band gap shifts due to the change of refractive index or periodicity. To solve those problems, we infiltrate polydimethylsiloxane (PDMS) into the intervals between regularly arrayed hollow SiO2 nanospheres, inspired by the cobbled road prepared by embedding stone in the bulk cement matrix. Consequently, the as-prepared PCs films show brilliant colors, invariable stop-bands, and excellent mechanical robustness. Moreover, the water contact angle even reached 166° after a sandpaper abrasion test. The combination of brilliant colors, invariable stop-bands, and excellent robustness is significant for potential application in paint and external decoration of architectures.

Facile fabrication of wear-resistant multifunctional surfaces on titanium alloy substrate by one-step anodization and modification with silicon dioxide nanoparticles

This paper describes a simple, facile, low-cost method of fabricating a wear-resistant surface on titanium alloy substrates by single-step anodization and modification with silicon dioxide particles. The method produced a TiO2–SiO2 composite surface with micro- to nanohierarchical structure, which became multifunctional after fluoroalkylsilane modification. The surface not only showed excellent superhydrophobicity [contact angles (CAs) > 150°, sliding angles (SAs) ≤ 8°] but also exhibited better repellency of complex whole blood (CAs = 153° ± 2°, SAs = 9°). Furthermore, the wear resistance of the surface was investigated by sandpaper abrasion test. The results showed that the mechanical wear resistance of the TiO2–SiO2 composite surface was more than three times that of the surface prepared only by the electrochemical technique, and the surface still maintained the capacity of hydrophobicity even after 33.6 m of wear under conditions of 3400 Pa and 360# sandpaper. The method mentioned in this paper could be a candidate for the production of abrasion-resistant and super-repellent titanium alloy.

Semitransparent, durable superhydrophobic polydimethylsiloxane/SiO2 nanocomposite coatings on varnished wood

Abstract A superhydrophobic surface on wood can prevent water adhesion and absorption. However, the practical applications of such a non-wetting surface are hindered by the fragility of the microscopic roughness features that are essential for superhydrophobicity. In this study, semitransparent, mechanically durable superhydrophobic coating was successfully deposited on varnished wood via a simple dip-coating method based on polydimethysiloxane (PDMS)/silica (SiO2) nanocomposites. The surface microstructure and roughness of the hybrid coatings on wood are governed by the mass ratio of SiO2 to PDMS. When the nano-SiO2 particle content reaches a critical level, dual-scale features with micro-scale roughness superimposed with a nanostructure can be formed in the surface coatings, resulting in excellent water-repellency with a contact angle above 150° and a sliding angle below 10°. The coated wood surface maintained essentially the original colour and aesthetic appearance despite slightly declined optical transparency of the hybrid coating caused by aggregation of silica nanoparticles. Sandpaper abrasion tests revealed that the superhydrophobic PDMS/SiO2 hybrid coating on wood retained its microstructure and superhydrophobicity after being repeatedly abraded.

Spray-deposition and photopolymerization of organic-inorganic thiol-ene resins for fabrication of superamphiphobic surfaces.

Superamphiphobic surfaces, exhibiting high contact angles and low contact angle hysteresis to both water and low surface tension liquids, have attracted a great deal attention in recent years because of the potential of these materials in practical applications such as liquid-resistant textiles, self-cleaning surfaces, and antifouling/anticorrosion coatings. In this work, we present a simple strategy for fabricating of superamphiphobic coatings based on photopolymerization of hybrid thiol-ene resins. Spray-deposition and UV photopolymerization of thiol-ene resins containing hydrophobic silica nanoparticles and perfluorinated thiols provide a multiscale topography and low-energy surface that endows the surface with superamphiphobicity. The wettability and chemical composition of the surfaces were characterized by contact-angle goniometry and X-ray photoelectron spectroscopy, respectively. The hierarchical roughness features of the thiol-ene surfaces were investigated with field-emission scanning electron microscopy. Droplet impact and sandpaper abrasion tests indicate the coatings respectively possess a robust antiwetting behavior and good mechanical durability.