Good Water Repellency Research Articles

Design of epoxy composites via molecular orbital modulation and enhanced π-πF interactions achieving synchronous improvement of electrical and mechanical performance

The stacked aromatic rings in bisphenol A epoxy resins provide good mechanical properties and thermal stability while leading to the transport of conjugated delocalized electrons, which dramatically affects the insulation properties of the material. This contradiction leads to performance bottlenecks in epoxy-based encapsulation materials, further limiting the development of high-voltage semiconductor devices. In this study, fluorophenyl-modified epoxy monomers (FPMEPs) are designed to enrich the intermolecular interactions in an aromatic system while inhibiting the charge transport process, thereby solving the contradiction between the electrical and mechanical properties. Firstly, FPMEP with high insulation properties was designed by theoretical calculations and then synthesized by highly selective click chemistry. The fluorophenyl modulates the molecular orbitals of epoxy monomers and acts as a deep trap to inhibit charge injection and transport processes. Further, the π-πF stacking between the aromatic system and fluorophenyl enhances the interaction of the matrix molecules and solves the dispersion problem of fluorinated graphene (FG) fillers. The FPMEP/FG composites thus exhibit a considerable improvement in electrical and mechanical properties (breakdown strength of 39.8 kV/mm, dielectric loss of 0.011@50 Hz, tensile strength of 68.8 MPa, and adhesive strength of 2.15 MPa), and demonstrate good water repellency and aging durability. This matrix-filler synergistic modification strategy provides new insights into the design of insulation material.

Octadecylamine modified gelatin-based biodegradable packaging film with good water repellency and improved moisture service reliability

Industrial gelatin is a good candidate for fabricating biodegradable packaging film, but the strong hydrophilicity of gelatin-based film lowers its moisture service reliability. Herein, we demonstrated a low surface energy water repellency surface design combined with covalent cross-linking for decreasing the water absorption and improving the moisture service reliability. Biodegradable octadecylamine (ODA) was chosen as the low surface energy providing material to fabricate the water repellency surface through a dehydration condensation reaction between the amine groups of ODA and gelatin chains via tetra-hydroxymethyl phosphonium chloride (THPC) in an aqueous phase. THPC also was employed as the cross-linking agent to form covalent bonding between the gelatin chains. The results determined that ODA modification and covalent cross-linking endowed the gelatin-based film with good water repellency and improved moisture service reliability. But high dose of ODA would result in phase separation and mechanical strength loss of the fabricated film. Additionally, ODA modification did not change the biodegradability of gelatin-based film, all the modified films were completely biodegradable in natural soil. Considering the sustainable modification process and abundant raw materials, the proposed strategy facilitates the effective utilization of low value industrial gelatin and provides a facile way for gelatin-based film as biodegradable packaging film.

One-Step Spraying Strategy for Fabricating Bioinspired, Graphene-Based, and Multifunctional-Integrated Coatings on Structural Steel with Good Water Repellency, Fireproofing, Anticorrosion, and Durability.

Traditionally, many coatings were merely concentrated on settling the inherent fire protection problem of steel structures, while surface contamination and corrosion susceptibility should also be considered. Concurrently addressing these problems in fireproof efficiency and surface multifunctionality has become an issue of great significance in further expanding the application value in industrial and daily scenarios. Based on this condition, ecofriendly, graphene-based, and superhydrophobic coatings with multifunctional integration were constructed on steel via a one-step spraying method. The as-prepared coatings mainly consist of epoxy resin (EP), silicone resin (SR), a cyclodextrin-based flame retardant (MCDPM), expandable graphite (EG), and multilayered graphene (MG). The results demonstrate that the water contact angle (WCA) and water sliding angle (WSA) of as-prepared coatings can reach 156.8 ± 1.6 and 5.8 ± 0.7°, respectively, revealing good water repellency and self-cleaning properties. The coatings can also exhibit adequate adaptability for various substrates including wood, polyurethane foam, and cotton fabrics. Besides, good durability and robustness of coatings have been also verified via acid/alkali immersion, outdoor exposure, O2/plasma etching, and linear abrasion tests. Simultaneously, the coatings can exhibit excellent anticorrosion capacity for steel materials via a double barrier effect. Most importantly, the coatings have exhibited the lowest backside temperature (234.5 °C) during fire impact tests, suggesting excellent fireproof and heat insulation performance. This fact can be ascribed to the conjunct action between the physical/chemical charring process of flame retardants and the remarkable thermal stability of graphene. Consequently, this article can be expected to further promote the development and application of multifunctional-integrated coatings for steel structures in more fields.

Fabrication of superamphiphobic micro-reentrant structures by inverted electrochemical deposition

Due to excellent oil resistance and shortened liquid-solid contact time, superamphiphobic surfaces have promising application prospects in oil transportation, and petroleum pollution control. Although superamphiphobic surfaces have been constructed on various substrates, there is still a lack of high-efficient methods for fabricating micro-reentrant structures on engineering metal substrates. This paper proposes a new method combining laser processing and inverted electrochemical deposition techniques to achieve high-efficient and large-scale fabrication of superamphiphobic surfaces on copper substrates. Firstly, micropillar array structures are constructed by laser processing, and the structures exhibit excellent superhydrophobicity after low surface energy modification. Then, inverted electrochemical deposition is performed after polishing the top of the array, and local angle of the gas/liquid interface can be controlled by adjusting the distance between the top of the micropillar and the electrolyte level, thus regulating micro-morphology of the roof structure. The influences of electrochemical deposition parameters on characteristics of the micro-reentrant structures are systematically investigated. Finally, superamphiphobic micro-reentrant structures (roof diameter > 190 μm, micropillar spacing <250 μm) with water and oil contact angles exceeding 150° are prepared after lowering the surface energy of the deposited structures. After anti-fouling, blowing, ultrasonic vibration, and tape adhesion tests, the prepared superamphiphobic micro-reentrant structures maintained good water and oil repellency, showing excellent chemical stability and durability. The research may provide a simple, efficient, and low-cost method for high-efficient constructing superamphiphobic surfaces on engineering metal substrates, enriching the fabrication techniques of micro-reentrant structures and facilitating their practical applications.

Emulsified oil-water separation properties of superhydrophobic/superoleophilic surface by emulsion droplets impacting dynamic behavior

Superhydrophobic/superoleophilic materials with excellent separation property are urgently needed for the clarification of water from oil-water emulsions, however, the lack of interfacial contact dynamics in the separation process is not beneficial to extensive application for them. Herein, a superhydrophobic/superoleophilic mesh was successfully prepared by spraying fluorinated polyurethane (FPU), silicon dioxide (SiO2) and carbon nanotubes (CNTs). The prepared mesh exhibited excellent superhydrophobic/superoleophilic performance, accomplishing a 1636.9 L m−2h−1 flux and a high separation efficiency above 99.8 % for water-in-oil (W/O) emulsions. The dynamic behavior of emulsion droplets impacting on the prepared mesh was innovatively investigated by experiment and simulation. As the oil content of emulsion droplets increased from 0 wt% to 2 wt%, the maximum spreading diameter (Ddmax) of emulsion droplets decreased from 5.57 mm to 5.28 mm, which can be attributed to the oil capture ability of the superhydrophobic/superoleophilic surface. Simultaneously, the maximum jet height (Hdamx) and the retraction velocity of the droplets firstly decreased and then increased. The results revealed that the oil film captured on the surface possessed good lubricity and water repellency, which could accelerate the dislodging of water from the surface and enhance separation performance. The separation mechanism of superhydrophobic/superoleophilic surface revealed by the contact dynamics study provided a novel path for the fabrication of emulsified oil-water separation materials.

Optimised fluorine free polysiloxane based water repellent for cellulosic fabric

This research focuses on creating a new water-repellent finish for textiles utilising a sol-gel process and the combination of 3-glycidyloxypropyltrimethoxysilane (KH560) and gamma-Methacryloxypropyltrimethoxysilane (KH570) as a precursor which was then modified with branched silicone through sol-condensation. A fluorine-free, new-generation polysiloxane-based water repellent was prepared and analysed to achieve the best water repellent characteristics. Different parameters and conditions were tested during the preparation of chemicals to achieve this. After preparation, all the chemicals were characterised using various scientific analysing tools such as Fourier Transform Infrared radiation, thermogravimetric analysis, particle size analysis, contact angle and water-repellent testing. Following the particle size investigation, it was discovered that the particle size distributions for these samples were homogenous and advantageous, allowing for more efficient contact and penetration with the textile fibres. The results of this study confirm the existence of functional groups that can contribute to the desirable characteristics of the compounds to repel water with one coupling agent, KH570:KH560 = 0.02 mol:0.04 mol, showing particularly good water-repellence performance.

Blood and bacterium repellent superhydrophobic coating based on assembly of nanoparticles

A new superhydrophobic coating with low surface roughness is prepared by facile spray-coating method for robust blood and bacterium repellent application. The superhydrophobic coating does not only display good water repellency with a large contact angle of 171.4°, but also shows a satisfactory mechanical stability (a contact angle of 151.8° after 100 abrasion cycles). Furthermore, the superhydrophobic coating is evaluated to apply in blood and bacterium repellency. It is observed that the blood droplet can roll off the surface within 0.5 s, and the bacteria count is reduced from 120 cfu/cm2 to 5.0 cfu/cm2. The good comprehensive performance is attributed to good superhydrophobicity and low surface roughness. This work thus provides a facile method to improve blood and bacterium repellent performance of superhydrophobic coating for biomedical application.

Ultra-thin parylene-aluminium hybrid coatings on nanocellulose films to resist water sensitivity

Non-sustainable single-use plastics used for food packaging needs to be phased out. Films made from cellulose nanofibrils (CNFs) are suitable candidates for biodegradable and recyclable packaging materials as they exhibit good mechanical properties, excellent oxygen barrier properties and high transparency. Yet, their poor water vapour barrier properties have been a major hindrance in their commercialisation. Here, we describe the preparation of 25 μm thick CNF films with significantly improved water vapour barrier properties after deposition of ultrathin polymeric and metallic coatings, parylene C and aluminium, respectively. When first adding a 40 nm aluminium layer followed by an 80 nm parylene layer, i.e. with a combined thickness of less than one percent of the CNF film, a water vapour transmission rate of 2.8 g m−2 d−1 was achieved at 38 °C and 90 % RH, surpassing a 25 μm polypropylene film (4–12 g m−2 d−1). This is an improvement of more than 700 times compared to uncoated CNF films, under some of the harshest possible conditions a packaging material will need to endure in commercial use. The layers showed a good and even coverage, as assessed by atomic force microscopy, and the parylene-coated surfaces were hydrophobic with a contact angle of 110°, providing good water repellency.

Fabrication of glycerol functionalized silica nanoparticles via pickering emulsion for durable, superhydrophobic fabrics

Stable oil-in-water Pickering emulsions were successfully developed via the simplest approach: amine-terminated polydimethylsiloxane with very high viscosity and low surface free energy was encapsulated by glycerol functionalized silica NPs using a rotor-stator device. The factors affecting the Pickering emulsions performance were investigated. At a certain process (silica NPs concentration: 3 wt%, Oil/water ratio: 1:20, emulsifying speed: 15,000 rpm, emulsifying time: 5 min), it gave smaller and more stable emulsions. Then the Pickering emulsion was applied on plain weave cotton and polyester fabrics through conventional pad-dry-cure method. The coated substrates showed superhydrophobicity and maintained good water-repellency even after 30 standard laundering cycles, which are attributed to the synergistic effect of low surface free energy composite and hierarchical roughness. By contrast, fabrics coated with classical emulsifiers stabilizing Pickering emulsion adopting the same recipes were quickly wetted by liquid droplets.

Multifunctional modification of silk fabrics via a combination of sophora flower extract, phytic acid and silicone-containing organics: Flame retardancy, water repellency, antibacterial activity and ultraviolet resistance

Herein, a multifunctional composite coating is constructed on silk fabrics by a facile impregnation strategy. In detail, the pre-period involves the aggregation growth of sophora flower extract/phytic acid-lanthanum ion-silk fibroin complex network, while the post-period introduces a water repellent layer that is composed of hydroxyl-terminated polydimethylsiloxane and hexadecyltrimethoxysilane composite. Benefiting from the synergistic effect of P, Si and N elements, the optimized finished silk sample denoted as D/FR/WR-SF exhibits a limiting oxygen index value of up to 29.3%, and shows a damage length as low as 9.4 cm in the vertical burning test. Since the sophora flower extract contains flavonoids such as rutin and quercetin, it confers good antibacterial activity and ultraviolet resistance to silk fabrics. The results display that D/FR/WR-SF inhibits the colony propagation of Escherichia coli and Staphylococcus aureus, and achieves an ultraviolet protection factor value of 38.61 compared with the control silk fabrics. Attributed to the directional arrangement of long-chain alkane and Si-CH3, D/FR/WR-SF exhibits good water repellency with a water contact angle of 138°. Additionally, D/FR/WR-SF also presents satisfactory washing resistance (integrated properties after 25 laundering cycles). Therefore, such a complete multifunctional composite coating scheme shows great potential for expanding advanced textile applications.

Nanobubble Technology for A Water-Repellent Treatment on Cotton Fabrics: A Comparative Study

Recently, a significant interest in eco-friendly textile products and processes has been noted among consumers and producers. In this respect, nanobubble technology is emerging as a green alternative. In this study, water-repellent cotton fabrics were produced with exhaustion and nanobubble technology (e-flow method) using a short-chain fluoropolymer. The currently most developed substituents are based on molecules with short fluorine carbon chains. The wettability, mechanical properties, air permeability and treatment durability were evaluated. The untreated and treated cotton fabrics were analyzed with ATR-FTIR (Fourier transform infrared attenuated total reflectance) and SEM (scanning electron microscopy) to reveal chemical and morphological modifications. The obtained results show that cotton samples treated with short-chain fluoropolymers, nontoxic and eco-friendly finishing chemicals, and nanobubble technology have good water repellence and good washing durability. Due to their size and structure, nanobubbles possess distinct properties that make them particularly effective at improving water quality, enhancing water treatment processes, and improving productivity in industrial applications. Nanobubbles have a strong negative surface charge that keeps them stable in liquid, prevents them from coalescing, and enables them to physically separate small particles and droplets from water, such as emulsified fats, oils, and grease.

A facile strategy to fabricate antibacterial hydrophobic, high-barrier, cellulose papersheets for food packaging

As a traditionally used packaging material, natural cellulose-based paper has poor barrier properties to water and oxygen, which severely limits its wide application in food packaging. In this study, we report a new sustainable approach to producing hydrophobic, high-barrier, and antibacterial packaging materials from cellulose paper. In this process, commercially available microcrystalline cellulose was first modified by long-chain stearic acid to form hydrophobic microcrystalline cellulose ester and then mixed with stearic acid as filler in the subsequent surface coating of bagasse fibre paper. The microcrystalline cellulose ester/stearic acid-coated paper (MSP) exhibited good water repellency and oxygen barrier activity due to a continuous hydrophobic film that formed, which completely covered the pores of the original bagasse fibre paper. The coated MSP sample also showed excellent dimensional stability in water and a good wet tensile strength of 16 MPa. In addition, poly(hexamethylene guanidine) (PHMG) was chemically grafted onto the free carboxyl groups of the MSP surface layer, and the resulting MSP-g-PHMG samples exhibited excellent antibacterial activity against Escherichia coli and Listeria monocytogenes. The biodegradable cellulose-based MSP-g-PHMG sample significantly delayed the decay of raspberry during storage, indicating its potential application in food packaging.

Facile Preparation of a Robust Superhydrophobic SiO2/Epoxy Composite Coating with Favorable Corrosion and Scale Inhibition Performance

Superhydrophobic surfaces with good water repellency are widely studied, but their complex preparation process and poor durability limit their practical application. Herein, a simple and environmentally friendly method to prepare a robust superhydrophobic coating is proposed and its application in the field of corrosion prevention and scale inhibition is explored. Environmentally friendly and low‐cost SiO2 nanoparticles modified by octadecyl trimethoxysilane (ODMS) are mixed with epoxy resin and sprayed onto the surface of metal substrates. The prepared ODMS–SiO2/epoxy resin composite coating has a water contact angle (WCA) of 161.5°, exhibiting excellent superhydrophobicity. In addition, the prepared coating maintains the original microstructure and good superhydrophobicity (WCA is 155°) after 30 cycles of wear test under 200 g load, showing excellent mechanical stability. The inherent superhydrophobic property also endows the coating with excellent corrosion and scale inhibition. The impedance of the composite coating is two orders of magnitude higher than that of the pure epoxy coating. The scaling amount of superhydrophobic composite coating in 24 h is 47% of that of epoxy resin coating. This work provides a new strategy for constructing multifunctional superhydrophobic coatings with excellent mechanical stability, corrosion resistance, and scale inhibition.

Robust Superhydrophobic Coatings for Enhanced Corrosion Resistance and Dielectric Properties

Multifunctional super-repellent composite coatings play an important part in academic and industrial fields, while it is still a great challenge to effectively integrate a variety of functions into one material. Mg alloys having low density, high strength-to-weight ratio, and good shielding, are widely used in electronic devices, while it is susceptible to sever corrosion especially in moist air and ocean atmosphere. Here, a versatile superhydrophobic coating with organic-inorganic hybrid structure and hierarchical surface textures, integrating robust wettability with design manipulation is synthesized by assembling modified SiO2 nanoparticles on polytetrafluoroethylene (PTFE) layer on the AZ31 Mg alloy. The composite coating has good water repellency with a contact angle of 170.5°, due to the micro/nano textures and low surface energy. The composite coating increases the corrosion potential of AZ31 Mg from −1.483 V to −1.243 V, and reduces the corrosion current density by 3 orders of magnitude. Remarkably, the superhydrophobic coating displays enticing damage-resistance (&gt;40 cycles), superior environmental stability (thermal shock and outdoor placement) and self-cleaning function. Moreover, the composite coatings display excellent electrical properties with superior voltage resistance (&gt;30 V/μm), and high resistivity (&gt;1012 Ω∙cm), as well the coating has a low dielectric constant (≈3.91) and dielectric loss (0.0094), which are great advantages for the electronic or electrical engineering applications. We expect that the versatile super-repellent coating can be used as candidates for novel advanced energy materials, especially in harsh environments.

Preparation of multicolor microcapsules and their application in smart color-switching textiles

Spiropyran and spiroxazine photochromics have attracted increasing attention in optical data storage, optical switches, and anti-counterfeiting for decades. To expand the applications of spiropyran and spiroxazine, the durability and multi-color changes of spiropyran and spiroxazine still need to be explored. In this article, based on the subtractive principle of dyes, multi-color spiropyran and spiroxazine microcapsules with uniform particle sizes were prepared by the interfacial polymerization method via using compounds (spiropyran and spiroxazine) of different colors as the core material, and polyurethane as the shell material. Among them, toluene diisocyanate and polyethylene glycol constitute the hard and soft segments of polyurethane, respectively. The color of spiropyran and spiroxazine microcapsules can effectively switch between color and colorless, showing excellent photo fatigue resistance. The average particle size of microcapsules is 2.951 µm, and the particle distribution index value is 0.314, which shows the particle size is small and uniform. The maximum thermal decomposition temperature is 426°C, demonstrating good thermal stability. The hydrophobic photochromic fabric was prepared by coating multi-color spiropyran and spiroxazine microcapsules on cotton knitted fabric and hydrophobic treatment. The hydrophobic photochromic fabric is hydrophobic and stain resistant, and exhibits multi-color dynamic switching and long-lasting use. After 50 cycles of washing, the water contact angle of the fabric remains about 109°, showing its good washing resistance and water repellency. In addition, spiropyran and spiroxazine microcapsules are also applied in template and screen printing to impart rich and dynamic color-changing effects to fabrics, fabricating photochromic fabrics. Photochromic fabrics have potential applications in civilian and military fields.

Multifunctional MXene/CNT-based layered film for icing detection, anti-icing, and deicing application

Icing phenomenon usually happens in our daily life, especially in the cold winter or in high altitude areas, which makes us feel inconvenient and greatly threats some fields such as civil aviation or the manufacturing industry. In this study, a multifunctional film with properties of icing detection, anti-icing and deicing was fabricated. One-dimensional material carbon nanotube (CNT) and two-dimensional material Ti3C2Tx MXene were combined by two-step vacuum filtration. Polydimethylsiloxane (PDMS) as the flexible hydrophobic materials was then used to encapsulate layered film. Additionally, PDMS curing process on the sandpaper could make the surface of MXene/CNT layered film possess micro-structures. The low surface energy material PDMS and rough surface structures endow MXene/CNT layered film with good water-repellency. Compared with pure PDMS film (103°), the contact angle of MXene/CNT layered film surface reaches 128°. The result exhibits that a waterdrop(100uL) on the layered film surface takes 1425s to be frozen, which takes longer time than glass and pure PDMS. Additionally, excellent sensibility of the layered film could be used to detect icing phenomenon. The result manifests that gauge factor (GF) of MXene/CNT film reaches 15051 so that different icing stages could be identified by layered film clearly. MXene/CNT layered film possesses good electric heating and photo-thermal properties. The result shows that surface temperature can reach 89 °C with the 2.5 V voltage supply, and temperature reaches 95 °C through the radiation of near-infrared lamp as well. The dual-driven heating of MXene/CNT layered film shows the ability of deicing. 1000 mg ice just takes 223s to be melted entirely by 2.5 V input voltage, and 269s by radiation of 200 mW/cm2, respectively. The multifunctional MXene/CNT based layered film prepared by a simple fabrication method that integrates hydrophobicity, dual-driven heating, and sensibility together, which shows potential application in icing detection, anti-icing, and deicing.

A Silicone Resin Coating with Water-Repellency and Anti-Fouling Properties for Wood Protection.

The strong hygroscopicity of wood greatly shortens its service life. Here, a simple impregnation modification approach was used to construct superhydrophobic silicone resin coatings on wood surfaces. Briefly, with hydrofluorosilicone oil (HFSO), tetramethyl tetravinyl cyclotetrasiloxane (V4), and hydrophobic SiO2 from industrial production as raw materials, superhydrophobic wood samples (water contact angle ~160.8°, sliding angle ~3.6°) can be obtained by simply dipping the wood in the HFSO/V4/SiO2 modifier solutions. As a result, the superhydrophobic silicone resin coating constructed on the wood surface still has good water repellency after finger touching, tape peeling, and sandpaper abrasion. When the mass ratio of HFSO to V4 is 2:1, the water absorption of the resulting wood after soaking in water for 24 h is only 29.2%. Further, the resulting superhydrophobic wood shows excellent anti-fouling properties. Finally, we believe that the impregnation modification method proposed in this study can be applied to the protection of cellulose substrates.

Fabrication of robust superhydrophobic micro-nano hierarchical surface structure using compression molding with carbon soot nanoparticles and thermoplastic polymer

The fragility of superhydrophobic surfaces limits applicability; therefore, development of hierarchical surface structure is an important strategy to achieve more robust superhydrophobic surfaces. Here, two-level micro-nano hierarchical polymer surfaces were fabricated by compression molding. Microstructured aluminum molds were produced through laser beam machining and then coated with carbon soot nanoparticles from acetone combustion. The nanostructure of soot nanoparticles combined with the mold microstructure was transferred onto the polypropylene sheet by compression molding. The replicated surface demonstrated superhydrophobicity with contact angles greater than 170° and sliding angles less than 10°. The mechanical robustness was confirmed with abrasion tests and adhesion tests. • We fabricated easily two-level micro-nano hierarchical polymer surfaces based on carbon soot nanoparticles and thermoplastic polymer. • Replicated surfaces performed good water repellence with the contact angle above 170° and the sliding angle under 6°. • Mechanical robustness of replicated surfaces was due to the upper micro-nanostructures as the protective microstructures that preserved the lower micro-nanostructures and the lowest nanostructures.

Synthesis of Nontoxic and Bio Based Oil and Water Repellent Polymers for Cotton Fabrics Using Stearic Acid, Succinic Acid, and Itaconic Acid

ABSTRACT Fluorocarbon-based oil and water repellents are considered best in textile finishing due to their excellent performance. Although, long chain fluorocarbons are effective oil and water repellents but they are toxic and being banned. Therefore, the present study develops two fluorine-free water-repelling polymers for cotton fabrics using ecofriendly recipes containing bio-based stearic acid and formaldehyde-free succinic acid and itaconic acid. One optimized recipe was achieved through polymerization between bio-based stearic acid and succinic acid, and other optimized recipe was achieved through polymerization between stearic acid and itaconic acid. These two recipes were applied to cotton fabric, and treated fabric exhibited a water repellency rating of 4 and an oil repellency rating of 1. The proposed polymers exhibited good oil and water repellency and washing durability up to 10 washing cycles. However, after 20 washing cycles, the proposed polymers exhibited water repellency for ironed fabric and zero oil repellency. The proposed polymers exhibited comparable or better testing results than commercial C6-based fluorocarbon. The characterization of the two best recipes was carried out through H-NMR Spectroscopy, scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD).

Water droplet bouncing on a hierarchical superhydrophobic surface fabricated by hydrothermal synthesis and ultraprecision machining

The ability of a water droplet to bounce on a superhydrophobic surface is an important indication of the surface wetting properties. In this study, a method integrating hydrothermal synthesis with ultraprecision machining (UPM) is reported for fabricating a hierarchical NiO-FAS-17 coated copper microgroove surface. Contact angles and water droplet bouncing behaviors were tested to evaluate the hydrophobicity of sample surfaces. Large contact angles over 160° and small contact angle hysteresis not exceeding 5° were recorded, showing good water repellency for the NiO-FAS-17 coating. The droplet bouncing results presented a larger first rebound height and stronger tendency of droplet break-up on the hierarchical NiO-FAS-17 coated microgroove surface in comparison with the NiO-FAS-17 coated flat surface, indicating a better hydrophobicity of the hierarchical surface. This reveals that the hydrophobicity of a surface can be enhanced by introducing UPM fabricated microgroove patterns into nanostructured surfaces that already possess good hydrophobicity.