Static Water Contact Angle Research Articles

Tailoring the wettability of surface-textured copper using sub-THz bursts of femtosecond laser pulses

In this work, copper surfaces were textured with sub-Terahertz bursts of femtosecond pulses. The wettability of Cu textured surfaces was investigated by measuring the static water contact angle (WCA) as a function of the number of sub-pulses and the intra-burst frequency. A superhydrophobic, antiadhesive response was observed when using bursts with a high number of sub-pulses (equal to or higher than 16) or a high intra-burst frequency (equal to or higher than 0.09 THz). Such trend was ascribed to the generation, under specific laser irradiation conditions, of a double-scale hierarchical texture on the sample surface, formed by sub-micro patterns with fine periodic ripples (LIPSS, Laser-Induced Periodic Surface Structures) and random nanoparticle decoration. Such texture enhances the hydrophobic behavior given by inherent adsorption of adventitious hydrocarbons on laser-processed and thermally-treated metal targets.

Preparation of durable superhydrophobic composite surface

Surface durability deficit is the most serious challenge confronting superhydrophobic surfaces. The creation of durable superhydrophobic surfaces is therefore of significant importance. In this study, we etched the surface of 1060 aluminum alloy coated with polydimethylsiloxane and nano-fumed silica (PDMS&NF-SiO2) using an infrared nanosecond laser to yield a durable superhydrophobic hybrid surface (SHS). We characterized the composite surface’s static water contact angle (WCA), water roll-off angle (WSA), morphology, and composition using a contact angle meter, scanning electron microscope (SEM), three-dimensional profilometer, energy-dispersive spectrometer (EDS), and Fourier-transform infrared spectroscopy (FT-IR). We also conducted tests for the mechanical durability and thermal stability of the SHS surface using tape peeling, steel wool friction wear, blade scraping, sand impact, and heat treatment. Results indicated that the WCA and WSA of the SHS surface were 158.1° and 6.2°, respectively. The SHS surface maintained its superhydrophobic properties after withstanding at least 150 tape peeling tests, 100 steel wool friction wear tests, 50 blade scraping tests, and a 450 g sand impact test, demonstrating exceptional mechanical durability. The surface WCA and WSA of the SHS after a 30-hour heat treatment at 100 ℃−300 ℃ were 157.4° and 7.6°, respectively, demonstrating good thermal stability. We believe that this study's design and fabrication of superhydrophobic composite surfaces offer new insights for the preparation of wear-resistant and high-temperature resistant superhydrophobic surfaces.

Biocompatible PVTF Coatings on Ti with Improved Bonding Strength

In this work, a poly(vinylidenefluoride-co-trifluoroethylene) (PVTF) coating on a titanium (Ti) substrate was prepared, and Ti metal surfaces were treated by physical or chemical methods to achieve a high bonding strength with PVTF. Scanning electron microscopy (SEM), atomic force microscope (AFM), and static water contact angles (WCA) were used to characterize the Ti metal surfaces. Further, mechanical stretching testing was employed to measure the bonding strength of PVTF coatings. The possible mechanism for the improved bonding strength could be the higher OH concentrations on Ti metal surfaces, which could lead to the formation of chemical bonds with the F atom of PVTF chains. Finally, a CCK-8 analysis of bone marrow mesenchymal stem cells (BMSCs) cultured on the PVTF coatings confirmed that the physical and chemical treatments had no significant differences in biocompatibility. Such a PVTF coating on a Ti substrate showed the potential of biomedical metal implants.

Durable superhydrophobic coatings for stainless-steel: An effective defense against Escherichia coli and Listeria fouling in the post-harvest environment

Increasing concerns revolve around bacterial cross-contamination of leafy green vegetables via food-contact surfaces. Given that stainless-steel is among the commonly used food-contact surfaces, this study reports a coating strategy enhancing its hygiene and microbiological safety through an antifouling approach via superhydrophobicity. The developed method involves growing a nickel-nanodiamond nanocomposite film on 304 stainless-steel via electroplating and sequential functionalization of the outer surface layer with nonpolar organosilane molecules via polydopamine moieties. The resultant superhydrophobic stainless-steel surfaces had a static water contact angle of 156.3 ± 1.9° with only 2.3 ± 0.5° contact angle hysteresis. Application of the coating to stainless-steel was demonstrated to yield 2.3 ± 0.6 log10 and 2.0 ± 0.9 log10 reductions in the number of adherent gram-negative Escherichia coli O157:H7 and gram-positive Listeria innocua cells, respectively. These population reductions were shown to be statistically significant (α = 0.05). Coated stainless-steel also resisted fouling when contacted with contaminated romaine lettuce leaves and maintained significant non-wetting character when abraded with sand or contacted with high concentration surfactant solutions. The incorporation of superhydrophobic stainless-steel surfaces into food processing equipment used for washing and packaging leafy green vegetables has the potential to mitigate the transmission of pathogenic bacteria within food production facilities.

Fabrication and mechanism of microspheres with tunable and control-released hydrophobicity: Ultra-low-density proppants

Ultra-low-density proppants with tunable and control-released hydrophobicity can meet different requirements of different fracture environments, thus playing an important role in unconventional reservoir exploration. In this study, for the first time, we designed and synthesized proppants with a molecular structure of γ-methacryloxypropyltrimethoxysilane (KH570)-styrene (St)-divinyl benzene (DVB) (FR-SDB) through suspension polymerization. FR-SDB was examined by Fourier-transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, and X-ray diffraction to understand the mechanism of tunable and control-released hydrophobicity. The results revealed that the hydrophobicity is related to the hydration reaction of chemically bonded KH570 and the difference in the reaction activities under different aqueous environments at different temperatures. The wettability of FR-SDB was evaluated according to the static water contact angle (θw) on its surface. The contact angle θw on the surface of FR-SDB can be tailored from the initial angle of approximately 50° to 80°–125° in a wide time range of 10 min to 144 h. FR-SDB exhibited ultra-low apparent density of approximately 1.028 g/cm3, high compressive strength, and a crushing ratio of ∼ 1.81% at closure pressure of 69 MPa.

Effect of silicon dioxide reinforcements on hydration properties of potato starch biopolymers

Starch is one of the most extensively researched raw materials for the production of biopolymers. A major drawback of biopolymers synthesized from thermoplastic starch is their poor water resistance. To overcome these limitations, various reinforcement fillers like nanoclay, silicon dioxide, and titanium dioxide are used. The current work employs the use of silicon dioxide (SiO2) as reinforcement fillers for potato starch. The addition of SiO2 was found to considerably improve the hydration properties (Tp) of the biopolymer films. The water solubility, moisture content, water vapour transmission rate, and static water contact angle of the films were found to be significantly decreased with increasing concentration of SiO2.

Co-Electrospun Poly(ε-Caprolactone)/Zein Articular Cartilage Scaffolds.

Osteoarthritis scaffold-based grafts fail because of poor integration with the surrounding soft tissue and inadequate tribological properties. To circumvent this, we propose electrospun poly(ε-caprolactone)/zein-based scaffolds owing to their biomimetic capabilities. The scaffold surfaces were characterized using Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, static water contact angles, and profilometry. Scaffold biocompatibility properties were assessed by measuring protein adsorption (Bicinchoninic Acid Assay), cell spreading (stained F-actin), and metabolic activity (PrestoBlue™ Cell Viability Reagent) of primary bovine chondrocytes. The data show that zein surface segregation in the membranes not only completely changed the hydrophobic behavior of the materials, but also increased the cell yield and metabolic activity on the scaffolds. The surface segregation is verified by the infrared peak at 1658 cm-1, along with the presence and increase in N1 content in the survey XPS. This observation could explain the decrease in the water contact angles from 125° to approximately 60° in zein-comprised materials and the decrease in the protein adsorption of both bovine serum albumin and synovial fluid by half. Surface nano roughness in the PCL/zein samples additionally benefited the radial spreading of bovine chondrocytes. This study showed that co-electrospun PCL/zein scaffolds have promising surface and biocompatibility properties for use in articular-tissue-engineering applications.

Design and performance optimization of self-cleaning coating on decorative UHPC surface

After long-term use, decorative UHPC may adhere to pollutants due to its hydrophilicity, which affects its aesthetics. Due to the smooth and dense exposed surface of UHPC, ordinary self-cleaning coatings have poor adhesion on its surface and are prone to peeling off due to rain wash in the environment, which cannot maintain the self-cleaning performance of UHPC for a long time. In this paper, a modified self-cleaning coating with a double layer structure was designed. The bottom layer is an epoxy resin (ER) adhesive layer to improve the adhesion performance of the coating to UHPC. The surface layer is a polymethylhydrosiloxane (PMHS) modified nano-SiO2 superhydrophobic layer, which satisfies the self-cleaning characteristics while constructing a regular rough superhydrophobic surface on the UHPC surface. The prepared superhydrophobic UHPC showed good self-cleaning performance, with a static water contact angle of 156.5and a sliding angle of only about 2.2. The performance test results show that the double-layer structure design makes the superhydrophobic coating have good wear resistance, water erosion resistance and excellent chemical stability. The surface functional groups, micro-area morphology and roughness were characterized by Fourier transform infrared spectrometer, scanning electron microscopy, optical profiler and atomic force microscopy, respectively. The reasons for the excellent self-cleaning performance and long-term stability of the coating were explained.

Ice Adhesion Evaluation of PTFE Solid Lubricant Film Applied on TiO2 Coatings

Ice formation affects the performance of many industrial components, including aircraft wings, spacecraft, and power transmission cables. In particular, ice build-up on airplane components increases drag and fuel consumption. A large number of studies have been carried out to reduce ice adhesion by developing passive methods such as icephobic coatings and active ice removal approaches such as mechanical vibrations or chemical-based solutions. Despite remarkable recent breakthroughs in the fabrication of icephobic coatings, passive ice removal solutions require higher durability to resist cyclical mechanical ice detachment treatments. Functionalized TiO2 coatings, applied using the suspension plasma spray (SPS) technique, have been shown to be robust and to have dual-scale characteristics in an ice accretion analysis. In this study, the icephobicity and mechanical durability of a novel duplex coating consisting of polytetrafluoroethylene (PTFE) solid lubricant films on TiO2-coated substrates were evaluated. Notably, various amounts of PTFE were applied on top of the TiO2 coating to identify the ideal quantity required to obtain optimal icephobic properties. Ice was generated in an icing wind tunnel, and the amount of accreted ice was evaluated to assess the anti-icing properties. Wettability parameters, including static water contact angle and contact angle hysteresis, were measured to determine the water mobility and surface energy. Ice shear adhesion to the PTFE-TiO2 duplex coating was measured using a custom-built test rig. The mechanical durability was assessed by measuring the ice shear strength for almost twenty icing–deicing cycles, and after five cycles, the roughness parameters and images taken from the surface of the samples were compared. The combination of PTFE solid lubricant film and TiO2 coating reduced ice adhesion by 70%–90% compared to that of a bare aluminum substrate (reference material). Additionally, the results showed that the application of a uniform layer of PTFE solid lubricant film on dual-scale TiO2 coating significantly reduced ice adhesion and maintained mechanical durability for 25 deicing cycles, making this combination a promising candidate for deicing approaches.

Hybrid concentrator photovoltaic/membrane distillation system for potable water production using new fabricated PS/ZIF_L membrane

A hybrid system is proposed to use solar energy as a heating source for the membrane distillation unit. Concentrating photovoltaic needs an efficient cooling system to manage the excess thermal load. Two microchannel heat sinks were proposed to keep the cells from thermal degradation and simultaneously transfer the excess thermal energy to the membrane distillation unit. The results showed a maximum coolant outlet temperature of 59 °C, which is adequate for the membrane distillation unit. A new composite electrospun nanofibrous membrane was successfully synthesized to reduce unfavorable membrane wettability. First, ZIF-L nanoparticles were synthesized and characterized to prove successful preparation, then used as a nanofiller with polystyrene as the polymer membrane matrix for the first time. SEM, XRD, FTIR, static water contact angle, membrane thickness, and porosity were introduced to prove nanofillers' successful preparation and encapsulation. The antiwetting phenomenon was proven by the measured contact angle of 160°. Furthermore, the fabricated membrane was tested experimentally on a lap scale direct contact membrane distillation unit with a productivity of about 4 kg/m2 h and 18 ppm water quality at 55 °C hot water temperature. Also, the introduced membrane outperformed the productivity of the commercial PVDF membrane at all examined operating conditions.

Biomimetic surfaces: Insights on the role of surface topography and wetting properties in bacterial attachment and biofilm formation

The study explores the impact of biomimetic surfaces on bacterial attachment and biofilm formation. Specifically, it investigates the effects of topographic scale and wetting behavior on the attachment and growth of Staphylococcus aureus and Escherichia coli on four different biomimetic surfaces: rose petals, Paragrass leaves, shark skin, and goose feathers. Using soft lithography, epoxy replicas with surface topographies similar to those of the natural surfaces were created. The static water contact angles of the replicas exceeded the hydrophobic threshold of 90°, while the hysteresis angles were found to be in the order of goose feathers, shark skin, Paragrass leaves, and rose petals. The results showed that bacterial attachment and biofilm formation were the lowest on rose petals and the highest on goose feathers, regardless of the bacterial strain. Additionally, the study revealed that surface topography had a significant impact on biofilm formation, with smaller feature sizes inhibiting biofilm formation. Hysteresis angle, rather than static water contact angle, was identified as a critical factor to consider when evaluating bacterial attachment behavior. These unique insights have the potential to lead to the development of more effective biomimetic surfaces for the prevention and eradication of biofilms, ultimately improving human health and safety.

Polydopamine anchored poly(2-methyl-2-oxazoline)/poly(4-vinyl pyridine) mixed brushes with switchable properties for pepsin adsorption

Mixed polymer brushes coating based on poly (2-methyl-2-oxazoline)/ poly(4-vinyl pyridine) (PMOXA/P4VP) was prepared by simultaneously grafting amine-terminated PMOXA and thiolterminated P4VP onto poly(dopamine) (PDA)-modified substrates in this work. The coatings were characterized by X-ray photoelectron spectroscopy, ellipsometry, zeta potential measurements, and the static water contact angle tests. The results indicated that it is feasible to control the components of the coating by adjusting the feed ratio of PMOXA to P4VP. Moreover, the zeta potential and the water contact angle of mixed brushes modified surfaces could be tuned by changing the environmental pH value and surface compositions. Finally, fluorescein isothiocyanate-labelled pepsin assay and surface plasmon resonance were performed to investigate the responsive adsorption/desorption of pepsin by PMOXA/P4VP mixed brushes. The results showed that by adjusting the fraction of PMOXA or P4VP, the PMOXA/P4VP mixed brushes coated surfaces could adsorb a high amount of pepsin at pH=3, and achieve a desorption efficiency of over 92% at pH=7.

Synergistic modification of short‐chain fluoro‐alcohol and siloxane end‐capping agents endowing an enhanced superhydrophobic waterborne polyurethane coating

AbstractWaterborne polyurethane (WPU) is an environmentally friendly product that can replace organic solvents with water. Still, its linear molecular chain structure and the presence of hydrophilic groups greatly affect water resistance and mechanical properties, limiting its wide application in the field of coatings. Herein, a series of fluorosilicone modified waterborne polyurethanes (FSiWPUs) were prepared by introducing tridecafluoro‐nonanol (TFN) and (3‐aminopropyl) triethoxysilane (APTES) into the ends of molecular chains of WPUs. These chains were constituted by different soft segments, including polybutylene adipate glycol, polycarbonate diol, or polytetramethylene ether glycol. Then fluorine element in TFN migrates and aggregates onto the surface during FSiWPU film‐forming to reduce the surface energy. Meanwhile, the hydrolytic condensation of APTES forms a Si–O–Si micro‐crosslinking structure. As a result, the two capping agents enable the modified FSiWPU to have better hydrophobicity, water resistance, and mechanical properties. The research results show that when the TFN:APTES molar ratio of capping agents introduced is 8:2, the static water contact angles of FSiWPUs with different soft sections reach 161.4°–165.3° and the maximum water absorption rate reduce to 8.9%–13.78%. Due to the simultaneous improvement of hydrophobic, water resistance, and mechanical properties, the modified FSiWPUs become the most promising candidates for superhydrophobic coatings.

19 nm‐Thick Grafted‐To Polymer Brushes onto Optimized Poly(Dopamine)‐Coated Surfaces

AbstractGrafting‐to polymer coatings are typically easy to apply, but the thickness of such coatings is typically limited to a few nanometers, which may hamper applications. This paper presents a grafting‐to coating approach that yields polymer brushes up to an unprecedented thickness of 19 nm. To this aim, an easy‐to‐apply poly(dopamine) (PDA) primer layer is optimized. PDA is an easy‐to‐apply, but highly complex and chemically not well understood primer layer. In this study, PDA is deposited on silicon substrates using several deposition protocols (pH 4–7 in presence of NaIO4, and from Tris solution at pH 8.5). The modified surfaces are characterized using X‐ray photoelectron spectroscopy, spectroscopic ellipsometry, static water contact angle measurements, and atomic force microscopy. Subsequently, block copolymers of poly(glycidyl methacrylate)20‐b‐poly(N‐isopropylacrylamide)n are attached onto the PDA films using a grafting‐to approach. The results indicate that the conditions of PDA deposition and the PDA film thickness strongly influence the stability and grafting efficiency of the block copolymers. PDA films deposited at pH 7 with NaIO4 are stable, and yield the most efficient grafting, with grafted polymer layers as thick as 19 nm. Polymer layers of such thickness are rarely achieved using grafting‐to procedures from solution.

Modular and Substrate-Independent Grafting-To Procedure for Functional Polymer Coatings.

The ability to tailor polymer brush coatings to the last nanometer has arguably placed them among the most powerful surface modification techniques currently available. Generally, the synthesis procedures for polymer brushes are designed for a specific surface type and monomer functionality and cannot be easily employed otherwise. Herein, we describe a modular and straightforward two-step grafting-to approach that allows introduction of polymer brushes of a desired functionality onto a large range of chemically different substrates. To illustrate the modularity of the procedure, gold, silicon oxide (SiO2), and polyester-coated glass substrates were modified with five different block copolymers. In short, the substrates were first modified with a universally applicable poly(dopamine) primer layer. Subsequently, a grafting-to reaction was performed on the poly(dopamine) films using five distinct block copolymers, all of which contained a short poly(glycidyl methacrylate) segment and longer segment of varying chemical functionality. Ellipsometry, X-ray photoelectron spectroscopy, and static water contact angle measurements confirmed successful grafting of all five block copolymers to the poly(dopamine)-modified gold, SiO2, and polyester-coated glass substrates. In addition, our method was used to provide direct access to binary brush coatings, by simultaneous grafting of two different polymer materials. The ability to synthesize binary brush coatings further adds to the versatility of our approach and paves the way toward production of novel multifunctional and responsive polymer coatings.

Development of facile superhydrophobic coating on rockwool for oil–water separation

Increased industrial oily effluent discharge endangers the environment and human health; hence, researchers are inventing practical technologies to extract oil from water. Superhydrophobic surfaces with oil-water separation capabilities have recently gained popularity. Considering this, the water-repellent and oil absorbent rockwool can be done by providing a superhydrophobic coating. In the present work, we have modified the pristine rockwool with HDTMS, TEOS, and SiO2 nanoparticles by simple immersion technique. The modified rockwool exhibits excellent water-repellent properties with a static water contact angle of more than 150° and a sliding angle of less than 10°. Additionally, it also shows excellent (100%) oil absorption properties. Oil absorption capacity and recyclability of the modified surfaces were examined by numerous sets of low/high viscous oil–water mixtures and emulsions. More importantly, oil can be reloaded after burning and squeezing of coated rockwool. Besides, the anti-dust property of modified rockwool also enhances oil recovery by keeping the surface clean from blocking particles. The performance of coated surface was investigated under several operating conditions, including elevated temperature and contact with acidic and alkaline solutions, which shows the industrial suitability after modified rockwool.

Development of sustainable superhydrophobic coatings on aluminum substrate using magnesium nanoparticles for enhanced catalytic activity, self-cleaning, and corrosion resistance

This study focuses on the development of sustainable superhydrophobic surfaces (SHSs) using magnesium nanoparticles (Mg-NPs) for catalytic applications and achieved excellent SHSs on the aluminum substrate along with a high static water contact angle of 160° and a low sliding angle of 2° via etching, immersion, and annealing method. The changes in surface chemistry, structural composition, and surface morphology were examined by using various characterization techniques, such as X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Herein, we describe the creation of Mg-NPs @SHS which is facile, eco-friendly, mechanically stable and fluorine-free, along with surface robustness as compared to other SHP coatings present in the literature whose surface textures become fragile and poor wear-resistance due to direct/indirect involvement of toxic chemicals such as fluorocarbons along with complicated preparation processes and costly processing procedures. It showed a low value of Ecorr (−0.425 V) and a high value of Icorr (2.016 × 10−5 A cm−2) than a non-coated Al plate of Ecorr is (−0.801 V) and Icorr (4.998 × 10−3 A cm−2). It has also remarkable self-cleaning, super buoyancy, anti-icing property, and excellent catalytic reduction of 4-NP to 4-AP with efficiency of 99.82% in the 1st and 84% in 13th cycle. These findings suggest that Mg-NPs @SHS on the aluminum substrate have promising applications in sustainable environmental practices and provide valuable insights for the fabrication of superhydrophobic surfaces on different materials. This work offers a new avenue for the development of high-performance catalysts with reusability and durability composed of magnesium particles.

Efficient fog collector with superhydrophobic coated surface

In this work, we developed a novel harp structure that collects water directly from fog in comparison with conventional Raschel mesh. Polyethylene (PE) monofilament was used as a collector’s element in the harp. The Raschel mesh in its particular design is quite anisotropic, shows elastic behavior breadth-wise while no stiffness is exhibited in transverse direction. A comparison of fog collection yield for the harp signifies that fog harvesting rate is four times higher than Raschel mesh, suggesting some alterations in monofilament diameter and collector element. Therefore, harp technology with cylindrical monofilaments can be deployed commercially to increase the efficiency of fog collectors, where mass and velocity of fog are inappropriate for Raschel mesh. In addition, silane-coated harp showed that surface hydrophobicity further enhances fog collection efficiency. The fog collector element (FCE) after silane coating significantly enhanced fog water collection yield. Samples were characterized by high resolution scanning electron microscope (HR-SEM), energy-dispersive x-ray (EDX) and atomic force microscope (AFM). Hydrophobicity was analyzed by static water contact angle and water collection yield.

Synthesis of highly dense and multi-branched carbon nanowalls by two-step growth combining different plasma chemical vapor deposition methods

We report a novel structure of carbon nanowalls (CNWs) synthesized by a two-step growth method using a radical injection plasma-enhanced chemical vapor deposition (RI-PECVD) as combined with a capacitively coupled plasma chemical vapor deposition (CCP-CVD). Scanning electron microscopy (SEM) observation shows that the CNWs grown by this method exhibit a multi-branched morphology with an average wall distance of ∼20 nm and a density of ∼74 wall units/μm2, which is more than 5 times higher than that of CNWs synthesized by the single-step RI-PECVD method. These branched-CNWs are crystalline and comprised of multilayer graphene as confirmed by the Raman and high-resolution transmission electron microscopy (HRTEM) analyses. A static water contact angle of 150° was obtained for the multi-branched CNWs indicating a superhydrophobic property. A possible growth mechanism of the branched-CNWs was also proposed through the investigation of the time-dependent growth from the second step.

Nanoscale chemical heterogeneity enables the co-existence of opposing superhydrophobic and hygroscopic properties

Superhydrophobicity and hygroscopicity are two properties that are theoretically exclusive to each other. The fabrication of functional fabrics with these two properties remains very challenging. In this work, it is demonstrated that a non-sticky superhydrophobic and hygroscopic fabric coating can be prepared via the photo polymerization of hexadecyl acrylate and methacrylic acid. On coating surface, the phase-separation-induced chemical heterogeneity has a unique feature of possessing elevated continuous hydrophobic domain and depressed hydrophilic domain, as evidenced by atomic force microscopy measurement. The elevation of hydrophobic domain (i.e., depression of hydrophilic domain) allows the hydrophilic domain to make negligible contribution to the surface wettability to water drop, but can absorb water molecules, thus inducing the unique superhydrophobic but hygroscopic property. The coating has a very low total surface energy of 22.61 mN m−1, with its polar part (0.01 mN m−1) being negligible, thereby showing a high static water contact angle of ~112° on flat glass slide. The coated polyester fabric shows a non-sticky superhydrophobicity with a static water contact angle of ~151° and a water shedding angle of ~10°, as well as good hygroscopic and anti-static properties. We anticipate that this novel coating and the reported strategy of generating the particular chemical heterogeneity may lead to the development of advanced special wettability coatings for various applications.