Search

A facile and inexpensive way have been developed to fabricate robust self‐cleaning superhydrophobic coating by depositing polymer layer on candle soot (CS) surface using dip coating method. The stability and robustness of the CS deposited superhydrophobic surface is much weaker due to weak interaction and nonchemical bonding with the substrate. We introduced a thin layer of polystyrene, polyethylene, polypropylene (PP), and polyvinylidene fluoride on CS surface in order to improve its mechanical properties. The fabricated surfaces with the use of respective polymers exhibited water contact angles of nearly 170, 174, 175, and 171° with sliding angles of 2, 1, 1, and 3°, respectively. Although, all the polymers used in this work exhibited excellent superhydrophobic and self‐cleaning surface property, we found that the PP deposited CS surface exhibit better stability against water jet hitting and water drop impact tests. The PP deposited CS surface almost maintained their surface properties even after 50 cycles of sandpaper abrasion and 20 cycles of adhesive tape peeling tests. The mechanical durability tests confirmed that PP is a better polymer to improve the long‐term durability of CS surface. Therefore, this simple, time saving, and inexpensive method for fabricating superhydrophobic coating can be used for potential industrial application. [ABSTRACT FROM AUTHOR]

Continuous oil–water separation is not only an important topic for scientific research but also for practical applications to clean oil from industrial oily wastewater and oil‐spill pollution. In this work, polyurethane sponges are coated by ZnO using dip coating technique. ZnO‐coated sponges are modified by stearic acid to achieve superhydrophobicity. The ZnO‐coated sponges exhibit water contact angle ≈165° and oil contact angle ≈0°. The prepared superhydrophobic sponge is sustained in oil–water separation and in separation of oil–hot water mixture. Also the wetting properties of the sponge are stable in mechanical test like cutting and twisting. Stearic acid modified ZnO‐coated sponge holds good promise for oil‐spill cleanup as well as oil/water separation from harsh environments. [ABSTRACT FROM AUTHOR]

In this study, the hydrophobic silica nanoparticles (NPs) are synthesized by simple sol–gel processing of polymethylhydrosiloxane (PMHS). The nanocomposite solution is prepared by adding hydrophobic silica NPs in polystyrene solution and applied on the skeleton of polyurethane sponge by simple immersion‐drying process. The as‐prepared sponges exhibited superhydrophobic property with water contact angle 161° and oil contact angle nearly 0° and can separate oil from oil–water and oil–muddy water mixture. The superhydrophobic sponge has sustainable anti‐wetting property under cross sectional cutting, pressing and twisting, and different pH environment. Such superhydrophobic sponge is suitable for practical application on a large scale. [ABSTRACT FROM AUTHOR]

A lotus leaf like self‐cleaning superhydrophobic coating has high demand in industrial applications. Such coatings are prepared by alternative dip and spray deposition techniques. A layer of polyvinyl chloride is applied on glass substrate by dip coating and then spray coated a suspension of hydrophobic silica nanoparticles at substrate temperature of 50 °C. This coating procedure is repeated for three times to achieve rough surface morphology which exhibits a water contact angle of 169 ± 2° and sliding angle of 6°. The superhydrophobic state of the coating is still preserved when water volume of 1.2 L is used to impact the water drops on coating surface. The stability of the wetting state of the coating is analyzed against the water jet, adhesive tape and sandpaper abrasion tests. The prepared superhydrophobic coating strongly repelled the muddy water suggesting its importance in self‐cleaning applications. [ABSTRACT FROM AUTHOR]

In the present research work, spray deposition technique is adopted for the fabrication of superhydrophobic coating on glass slide using TiO2 nanoparticles and polymethylhydrosyloxane (PMHS) composite. The prepared superhydrophobic coating revealed hierarchical surface morphology due to different micro and nanoscaled grains of TiO2 NPs/PMHS composite. The water drops hardly stay on the superhydrophobic coating and roll off the surface at sliding angle of 6° due to high water contact angle of 163 ± 2°. As a result, the prepared superhydrophobic coating revealed excellent self‐cleaning performance. To evaluate the mechanical durability the prepared superhydrophobic coating, the coating surface is exposed to water jet, water drop impact, adhesive tape peeling, and sandpaper abrasion tests. This coating approach can be applied to the substrates of any size and shape. [ABSTRACT FROM AUTHOR]

The preparation of superhydrophobic coating using cheap candle soot nanoparticles (CS NPs) collected from candle flame is a very novel research topic. A less than 30 nm sized candle soot particles are collected by passing through stainless steel mesh of pore size ̴30 nm. An optimum suspension of CS NPs and polydimethylsiloxane (PDMS) in chloroform is sprayed on clean glass substrate and dried at 100°C for 1 hour. The coating surface with water contact angle ̴173° and rolling angle ̴ 4° is achieved by spraying suspension of 100 mg CS NPs and 0.3 mL PDMS in chloroform. The stability of superhydrophobic coating is studied by finger‐wiping, water jet hitting, water dripping, adhesive tape, and sandpaper abrasion test. Result showed that the coatings prepared with an optimum 100 mg CS NPs in suspension are stable under water jet hitting and water dripping test. The superhydrophobicity is destroyed for four cycles of adhesive tape peeling and seven cycles of sandpaper abrasion tests. The coated substrate showed good self‐cleaning performance. The high water repellent and self‐cleaning property of the prepared coating can be adopted for industrial applications. [ABSTRACT FROM AUTHOR]

Self-cleaning coloured superhydrophobic surfaces can find huge market in decorative applications. Here we present a novel and simplistic approach to prepare self-cleaning yellow superhydrophobic polycarbonates by simple nitric acid treatment to attain yellow colour polycarbonate (PC) and subsequent surface silylation by methyltrichlorosilane (MTCS) for superhydrophobicity. A colour of PC can be controlled from light to dark yellow by simply varying the immersion time in nitric acid. The surface silylation by MTCS provides morphologies from nanofibers to nanospheres depending on reaction times. These morphologies are responsible to achieve superhydrophobicity on yellow coloured PC with water contact angle higher than 155° and sliding angle < 8°. The yellow superhydrophobic PC showed self-cleaning properties, where the dust particles from the surface were easily taken away by rolling water drops. After several water jet impact tests (oblique to vertical angle), no loss in superhydrophobic behaviour was observed confirming its mechanical stability. [ABSTRACT FROM AUTHOR]

Both surface morphology and surface energy of solid surface conclude its wettability, either in Wenzel’s hydrophobic or Cassie–Baxter’s superhydrophobic wetting state. The superhydrophobic silica coatings were prepared by spin deposition technique from a mixture of hydrophobically modified silica particles and polystyrene. To enhance the adherency of the coating on the substrate and also to improve the durability of the coating, polymer is especially utilized in the coating solution. The durability of the superhydrophobic coating was confirmed by resistency towards water jet impact. The consequence of number of spin deposited layers on the wettability of the coatings was precisely studied. The static and dynamic water contact angle of 158° and 9° were achieved on the coating surface. Freely rolling spherical water drops on the non-wettable solid surface are favourable for the self-cleaning effect and so the prepared superhydrophobic coatings revealed superior self-cleaning performance. An anti-corrosion performance of the superhydrophobic coating was also confirmed using electrochemical corrosion experiments in 3.5% NaCl solution with long immersion time. [ABSTRACT FROM AUTHOR]

The hydrophobic silica nanoparticles have been widely used in the fabrication of superhydrophobic surfaces. In this study, we prepared superhydrophobic coating using hydrophobic SiO2 nanoparticles by facile dip coat technique. After that, a layer of cyanoacrylate adhesive was applied to improve the durability of the superhydrophobic coating. Finally, the coating was annealed at 200 °C for 10 min. A water drop on prepared superhydrophobic coating showed contact angle ≈173° and sliding angle ≈1°. The prepared superhydrophobic coating revealed self‐cleaning behavior for more than 2 years. This approach can be useful for fabrication of superhydrophobic coating for practical industrial application including solar panel, windows glass, vehicle glass and fabrics, and so on. [ABSTRACT FROM AUTHOR]

Highlights • The superhydrophobic coatings were prepared using hydrophobic silica nanoparticles. • The simple dip and spray deposition techniques are used. • The coating were applied on different substrates of any size and shape. • The coating on every substrate revealed self-cleaning ability. Abstract Many technologies have surfaced through careful observation and investigation of unusual features of various species found in Nature. Among which, the remarkable non – wetting properties of lotus leaf has hugely occupied the minds of students, researchers and industrialists from last two decades. Due to high contact angle (>150°), water drops readily roll off the lotus leaf surface compiling dirt particles. This self – cleaning lotus effect has found huge attention in daily life. Many surfaces in day-to-day life eventually get contaminated due to the accumulation of dust/dirt or through air pollution. A huge amount of money, labor and energy is wasted in their restoration. The self – cleaning superhydrophobic coating is one of the best options for this problem. In this study, the suspension of hydrophobic silica nanoparticles was dip and/or spray coated on the body of motorcycle, building wall, mini boat, solar cell panel, window glass, cotton shirt, fabric shoes, paper (currency notes), metal, wood, sponges, plastic and marble. Every coated substrate exhibited superhydrophobicity with water contact angle nearly 160° and sliding angle less than 6°. The self-cleaning performance of the superhydrophobic coating applied on various substrates was thoroughly evaluated. The specific purpose of this article is to explore the possible industrial applications of self – cleaning superhydrophobic coatings. [ABSTRACT FROM AUTHOR]

Here we report, an easy, straightforward and novel way to prepare raspberry-like superhydrophobic silica coatings for self-cleaning applications. The hydrophobic silica particles were obtained by simple condensation of fluoroalkoxysilane (17FTMS) in ethanol at room temperature. These silica particles were embedded into the sol–gel processed silica matrix and deposited on glass plates. On this coating surface, water drops exhibited a contact angle of 152° and rolls off the surface at sliding angle of 10°. This extremely low sliding angle was employed to self-clean the superhydrophobic coating, where dirt particles accumulated on the surface of superhydrophobic coating was efficiently cleaned by quickly sliding water drops. The stability of the microstructure as well as the wetting properties of the coating surface was investigated by scratch resistance and water stream impact test. The superhydrophobic coatings endured against the scratch of applied force of ~150 mN. Such one pot synthesis of raspberry-like superhydrophobic silica coatings may open new avenue in the sublime field of superhydrophobic research. [ABSTRACT FROM AUTHOR]