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6 pages, 601 KiB

Open AccessEditorial

Superhydrophobic and Superoleophobic Surfaces: Key Points, Challenges and Applications

by Ioannis Karapanagiotis

Coatings 2023, 13(3), 551; https://doi.org/10.3390/coatings13030551 - 4 Mar 2023

Cited by 1 | Viewed by 2170

Abstract

Non-wettable surfaces have been uninterruptedly studied during the 20th century [...] Full article

(This article belongs to the Special Issue Superhydrophobic and Superoleophobic Surfaces)

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15 pages, 3134 KiB

Open AccessArticle

Long-Term Durability of Robust Super-Hydrophobic Co–Ni-Based Coatings Produced by Electrochemical Deposition

by Shuqiang Wang, Yanpeng Xue, Yanyan Xue, Cunjing Lv and Ying Jin

Coatings 2022, 12(2), 222; https://doi.org/10.3390/coatings12020222 - 9 Feb 2022

Cited by 4 | Viewed by 2079

Abstract

The long-term durability for two kinds of Co–Ni-based robust coatings, the Co–Ni super-hydrophobic (Co–Ni SHPB) coating and Co–Ni/WC super-hydrophobic (Co–Ni/WC SHPB) coating, was analyzed through an immersion test in 3.5 wt.% NaCl solution. The evolution of their surface properties was characterized by scanning [...] Read more.

The long-term durability for two kinds of Co–Ni-based robust coatings, the Co–Ni super-hydrophobic (Co–Ni SHPB) coating and Co–Ni/WC super-hydrophobic (Co–Ni/WC SHPB) coating, was analyzed through an immersion test in 3.5 wt.% NaCl solution. The evolution of their surface properties was characterized by scanning electron microscope (SEM) images, energy-dispersive spectrometry (EDS), a wettability measurement and X-ray photoelectron spectrometer (XPS), and the evolution of anti-corrosion mechanisms was evaluated with electrochemical measurements. The results show that as-prepared two kinds of robust coatings display a good long-term durability, with the Co–Ni SHPB coating and Co–Ni/WC SHPB coating losing their super-hydrophobicity after being immersed for more than 10 days. Additionally, both kinds of coatings present efficient corrosion protection even after long-term immersion. Full article

(This article belongs to the Special Issue Superhydrophobic and Superoleophobic Surfaces)

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13 pages, 4000 KiB

Open AccessArticle

Facile Preparation of Hydrophobic PET Surfaces by Solvent Induced Crystallization

by Elisabet Afonso, Aránzazu Martínez-Gómez, Andrea Huerta, Pilar Tiemblo and Nuria García

Coatings 2022, 12(2), 137; https://doi.org/10.3390/coatings12020137 - 24 Jan 2022

Cited by 8 | Viewed by 4011

Abstract

In this work, Polyethylene terephthalate (PET), one of the most widely consumed polymers, has been used as starting material for the development of non-stick surfaces through a fast, simple and scalable method based on solvent-induced crystallization to generate roughness, followed by a fluorination [...] Read more.

In this work, Polyethylene terephthalate (PET), one of the most widely consumed polymers, has been used as starting material for the development of non-stick surfaces through a fast, simple and scalable method based on solvent-induced crystallization to generate roughness, followed by a fluorination step. Several solvents were tested, among which dichloromethane was chosen because it gives rise to the formation of a particulate layer with rough topography. This particulate layer was covered by a polymer thin and smooth skin that must be removed to leave the rough layer as surface. The skin has been successfully removed by two strategies based on mechanical and chemical removal, each strategy producing different surface properties. A final treatment with a diluted solution of a fluorinated silane showed that it is possible to obtain PET surfaces with a water contact angle higher than 150° and low water adhesion. The reason behind this behavior is the development of a hierarchical rough profile during the induced polymer crystallization process. These surfaces were characterized by XRD, FTIR and DSC to monitor solvent induced crystallization. Topography was studied by SEM and optical profilometry. Wetting behavior was studied by measuring the contact angles and hysteresis. Full article

(This article belongs to the Special Issue Superhydrophobic and Superoleophobic Surfaces)

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13 pages, 1936 KiB

Open AccessArticle

Water Repellency/Proof/Vapor Permeability Characteristics of Coated and Laminated Breathable Fabrics for Outdoor Clothing

by Hyun-Ah Kim

Coatings 2022, 12(1), 12; https://doi.org/10.3390/coatings12010012 - 23 Dec 2021

Cited by 10 | Viewed by 6523

Abstract

This study examined the water repellency (WR), waterproof, and water vapor permeability (WVP) characteristics of twelve types of laminated and coated woven fabrics for outdoor clothing. These characteristics were compared with the fabric structural parameters, such as cover factor, thickness, and weight, and [...] Read more.

This study examined the water repellency (WR), waterproof, and water vapor permeability (WVP) characteristics of twelve types of laminated and coated woven fabrics for outdoor clothing. These characteristics were compared with the fabric structural parameters, such as cover factor, thickness, and weight, and surface modification (finishing) factors, such as coating, laminating, and Teflon treatments. In addition, an eco-friendly process for surface modification was proposed followed by a summary. Superior waterproof-breathable characteristics with 100% water-repellency were achieved in specimen 3 in group A by treatment with a hydrophilic laminated finish using nylon woven fabric with a cover factor between 0.7 and 0.9 in a 2.5-layered fabric, which was the best specimen with waterproof-breathable characteristics. A high WVP in the coated and laminated fabrics was observed in the fabrics with a low weave density coefficient (WDC) and low thickness per unit weight of the fabric, whereas superior water repellency and waterproof characteristics were observed in the high-cover-factor (WDC) fabric with appropriate fabric thickness. The determination coefficient (R²) from regression analysis between the WVP and fabric structural parameters indicated a higher contribution of the fabric structural parameters than surface modification factors, such as coating and laminating to the WVP in the coated and laminated fabrics. Furthermore, the cover factor was the most important factor influencing the WVP of the waterproof-breathable fabrics. Of twelve coated and laminated fabrics, the laminated nylon and nylon/cotton composite fabrics showed superior WVP with high WR and waterproof characteristics. Accordingly, based on the WR, waterproof, and WVP characteristics of the coated and laminated breathable fabrics, the laminating method, as an eco-friendly process, is recommended to obtain better waterproof-breathable fabrics. Full article

(This article belongs to the Special Issue Superhydrophobic and Superoleophobic Surfaces)

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13 pages, 5680 KiB

Open AccessArticle

A Study on the Corrosion Resistance of Hydrophobic Coatings on 65Mn Steel

by Yufen Zhang, Qingcheng Du, Tiegui Lin, Shawei Tang and Jin Hu

Coatings 2021, 11(11), 1399; https://doi.org/10.3390/coatings11111399 - 18 Nov 2021

Cited by 5 | Viewed by 2224

Abstract

Calcium stearate hydrophobic coatings with a hierarchical micro/nanostructure were prepared on 65Mn steel using direct current electrodeposition. The deposition time has a visible influence on the morphology, surface wettability and thickness of the coatings, but little effect on the phase composition. The corrosion [...] Read more.

Calcium stearate hydrophobic coatings with a hierarchical micro/nanostructure were prepared on 65Mn steel using direct current electrodeposition. The deposition time has a visible influence on the morphology, surface wettability and thickness of the coatings, but little effect on the phase composition. The corrosion behavior of the coated samples in 3.5 wt.% NaCl solution was also investigated. The prepared coatings at different deposition times show different corrosion resistance. The coating fabricated at 30 min has the best corrosion resistance due to the highest water contact angle and thicker coating. Full article

(This article belongs to the Special Issue Superhydrophobic and Superoleophobic Surfaces)

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12 pages, 2984 KiB

Open AccessArticle

New Approaches to Increasing the Superhydrophobicity of Coatings Based on ZnO and TiO₂

by Arsen E. Muslimov, Makhach Kh. Gadzhiev and Vladimir M. Kanevsky

Coatings 2021, 11(11), 1369; https://doi.org/10.3390/coatings11111369 - 8 Nov 2021

Cited by 3 | Viewed by 2272

Abstract

The work presented is devoted to new approaches to increasing the superhydrophobic properties of coatings based on zinc oxide (ZnO) and titanium dioxide (TiO₂). There is an innovation in the use of inorganic coatings with a non-polar structure, high melting point, [...] Read more.

The work presented is devoted to new approaches to increasing the superhydrophobic properties of coatings based on zinc oxide (ZnO) and titanium dioxide (TiO₂). There is an innovation in the use of inorganic coatings with a non-polar structure, high melting point, and good adhesion to ZnO, in contrast to the traditionally used polymer coatings with low performance characteristics. The maximum superhydrophobicity of the ZnO surface (contact angle of 173°) is achieved after coating with a layer of hematite (Fe₂O₃). The reason for the abnormally high hydrophobicity is a combination of factors: minimization of the area of contact with water (Cassie state) and the specific microstructure of a coating with a layer of non-polar Fe₂O₃. It was shown that the coating of ZnO structures with bimodal roughness with a gold (Au) layer that is 60-nm thick leads to an increase in the wetting contact angle from 145° to 168°. For clean surfaces of Au and hematite Fe₂O₃ films, the contact angle wets at no more than 70°. In the case of titanium oxide coatings, what is new lies in the method of controlled synthesis of a coating with a given crystal structure and a level of doping with nitrogen using plasma technologies. It has been shown that the use of nitrogen plasma in an open atmosphere with different compositions (molecular, atomic) makes it possible to obtain both a hydrophilic (contact angle of 73°) and a highly hydrophobic surface (contact angle of 150°). Full article

(This article belongs to the Special Issue Superhydrophobic and Superoleophobic Surfaces)

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16 pages, 2171 KiB

Open AccessArticle

Eco-Friendly Protective Coating to Extend the Life of Art-Works and Structures Made in Porous Stone Materials

by Mariateresa Lettieri, Maurizio Masieri, Marika Aquaro, Debora Dilorenzo and Mariaenrica Frigione

Coatings 2021, 11(11), 1270; https://doi.org/10.3390/coatings11111270 - 20 Oct 2021

Cited by 10 | Viewed by 3146

Abstract

The application of hydrophobic treatments to stone surfaces is the most common proven method to prevent, or at least limit, the degradation of stone-made constructions and artworks brought about by the ingress and action of water, in particular in the case of very [...] Read more.

The application of hydrophobic treatments to stone surfaces is the most common proven method to prevent, or at least limit, the degradation of stone-made constructions and artworks brought about by the ingress and action of water, in particular in the case of very porous stone materials. To avoid the use of protective products containing harmful solvents, new green products have been proposed. In this paper, an eco-friendly hydrophobic coating, based on a fluorine polymer dispersed in water, was deeply analyzed to evaluate its protective properties, especially for very porous stone substrates. To this aim, a wide characterization of treated and untreated Lecce stone elements, i.e., a stone typical of the Apulia region, was carried out to assess the optimum required amount, the effectiveness and the protective capability, even against graffiti staining, of the green hydrophobic treatment, still allowing the stone to retain adequate vapor permeability. The efficacy of the eco-friendly product was analyzed also after a short time (four weeks) of outdoor exposure. Suitable performance and short-term durability of the green hydrophobic coating were found, comparable or even greater than those reported in the current literature for other widespread commercial products, confirming the capability of the product to preserve porous stone surfaces even in absence of solvents in its formulation. The study also allowed to experiment with the “contact sponge” test as an appropriate method for evaluating the water absorption properties of the stone. Full article

(This article belongs to the Special Issue Superhydrophobic and Superoleophobic Surfaces)

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13 pages, 2936 KiB

Open AccessFeature PaperArticle

Durable Superhydrophobic Coating for Efficient Microplastic Removal

by Oriol Rius-Ayra, Alisiya Biserova-Tahchieva and Nuria Llorca-Isern

Coatings 2021, 11(10), 1258; https://doi.org/10.3390/coatings11101258 - 16 Oct 2021

Cited by 10 | Viewed by 3607

Abstract

The pollution caused by microplastics around the world is an increasingly significant issue that has to be tackled with different methods and technologies. Here, we report a straightforward and rapid process combining electrodeposition and electrophoresis to produce a durable superhydrophobic coating on an [...] Read more.

The pollution caused by microplastics around the world is an increasingly significant issue that has to be tackled with different methods and technologies. Here, we report a straightforward and rapid process combining electrodeposition and electrophoresis to produce a durable superhydrophobic coating on an aluminum substrate (UNS A91070) that has a static contact angle (153°), sliding angle (1°), and contact angle hysteresis (1°). Field emission scanning electron microscopy and high-resolution transmission electron microscopy showed the presence of a hierarchical structure with nanolayers that were 70 nm thick. The chemical composition was also analyzed using attenuated total reflectance-Fourier transform infrared spectroscopy and high-resolution X-ray photoelectron spectroscopy, which revealed that the hierarchical structure was composed of zinc laurate (Zn(C₁₁H₂₀COO)₂) that decreased the surface free energy of the system. Moreover, the coating showed high durability against abrasion caused by the P1200 SiC paper due to the presence of TiO₂ particles in the upper layers as well as the homogeneous chemical composition of the hierarchical structure. Finally, taking advantage of the superoleophilic properties of superhydrophobic surfaces, the ability of the coating to remove high-density polyethylene microplastics from water was studied. Full article

(This article belongs to the Special Issue Superhydrophobic and Superoleophobic Surfaces)

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14 pages, 3463 KiB

Open AccessArticle

Effect of Microcapsules of a Waterborne Core Material on the Properties of a Waterborne Primer Coating on a Wooden Surface

by Xiaoxing Yan and Wenwen Peng

Coatings 2021, 11(6), 657; https://doi.org/10.3390/coatings11060657 - 30 May 2021

Cited by 11 | Viewed by 2468

Abstract

Microcapsules of a waterborne core material were prepared using a waterborne primer. The microcapsules of the waterborne core material were added to the waterborne primer to explore the effects of different core–shell ratios and mass fractions of the microcapsules on the property of [...] Read more.

Microcapsules of a waterborne core material were prepared using a waterborne primer. The microcapsules of the waterborne core material were added to the waterborne primer to explore the effects of different core–shell ratios and mass fractions of the microcapsules on the property of the waterborne primer coating on the wooden surface. The results show that as the mass fraction of the microcapsules increased, the chromatic aberration increased by degrees, the glossiness decreased gradually, and the hardness increased by degrees, whilst—except for the coating with 0.50:1 microcapsules—the adhesion decreased gradually. When the mass fraction of the microcapsules increased, the impact resistance increased first and decreased later, or remained unchanged after reaching a certain value. When the mass fraction of the microcapsules increased, the elongation at the break increased first and decreased later. When the core–shell ratio was small and the mass fraction was between 5.0% and 15.0%, the coating had better liquid resistance. When the core–shell ratio was 0.67:1 and the mass fraction was 10.0%, the overall property of the coating on the Basswood was the best. The technology of microencapsulation provides a technical reference for the waterborne primer with self-repair qualities on the surface of wooden products. Full article

(This article belongs to the Special Issue Superhydrophobic and Superoleophobic Surfaces)

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14 pages, 4713 KiB

Open AccessArticle

Corrosion Behavior and Mechanical Properties of a Nanocomposite Superhydrophobic Coating

by Divine Sebastian, Chun-Wei Yao, Lutfun Nipa, Ian Lian and Gary Twu

Coatings 2021, 11(6), 652; https://doi.org/10.3390/coatings11060652 - 29 May 2021

Cited by 15 | Viewed by 3972

Abstract

In this work, a mechanically durable anticorrosion superhydrophobic coating is developed using a nanocomposite coating solution composed of silica nanoparticles and epoxy resin. The nanocomposite coating developed was tested for its superhydrophobic behavior using goniometry; surface morphology using scanning electron microscopy and atomic [...] Read more.

In this work, a mechanically durable anticorrosion superhydrophobic coating is developed using a nanocomposite coating solution composed of silica nanoparticles and epoxy resin. The nanocomposite coating developed was tested for its superhydrophobic behavior using goniometry; surface morphology using scanning electron microscopy and atomic force microscopy; elemental composition using energy dispersive X-ray spectroscopy; corrosion resistance using atomic force microscopy; and potentiodynamic polarization measurements. The nanocomposite coating possesses hierarchical micro/nanostructures, according to the scanning electron microscopy images, and the presence of such structures was further confirmed by the atomic force microscopy images. The developed nanocomposite coating was found to be highly superhydrophobic as well as corrosion resistant, according to the results from static contact angle measurement and potentiodynamic polarization measurement, respectively. The abrasion resistance and mechanical durability of the nanocomposite coating were studied by abrasion tests, and the mechanical properties such as reduced modulus and Berkovich hardness were evaluated with the aid of nanoindentation tests. Full article

(This article belongs to the Special Issue Superhydrophobic and Superoleophobic Surfaces)

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