Durable superhydrophobic PTFE films through the introduction of micro- and nanostructured pores

Zhang, Yao‐Yao; Ge, Qing; Yang, Longlai; Shi, Xiaojun; Li, Jiaojiao; Yang, De‐Quan; Sacher, E.

doi:10.1016/j.apsusc.2015.02.143

Cited by 60 publications

(22 citation statements)

References 46 publications

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“…This trend is similar to those of the composite SH coatings in our previous study [13] . The difference in the CA values of samples 1 and 2, with the surface temperature, Fig.…”

Section: Resultssupporting

confidence: 91%

“…Figure 10b shows the CA and SA as a function of water jet flow time at 200 kPa. The mechanical durability, resistance abrasion value is close to that of the Ever Ultra-Dry waterproof coating, a commercial product [13] (also see Figure S6 of the supporting information). The mechanical durability, resistance abrasion value is close to that of the Ever Ultra-Dry waterproof coating, a commercial product [13] (also see Figure S6 of the supporting information).…”

supporting

confidence: 59%

“…XPS used a PHI 5000 Versa Probe II, and SEM photomicrographs were made on a Hitachi S4800; the techniques employed can be found in references [4,13]. The sample containing pure CNTs (sample 1) shows strong hot water repellency.…”

Section: Methodsmentioning

confidence: 99%

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Repelling hot water from superhydrophobic surfaces based on carbon nanotubes

Wan¹,

Yang²,

Sacher

2015

J. Mater. Chem. A

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Superhydrophobic (SH) surfaces generally refer to those having a static water contact angle larger than 150° and a slide angle less than 10°, when both the surface and the water droplet are at room temperature. Most such surfaces lose superhydrophobicity when exposed to hot (e.g., >55 o C) water.Our recently published results (Z. indicated that hot water superhydrophobicity is maintained when the SH surface temperature is higher than that of the water droplet. Here, we find that carbon nanotubes (CNTs) can be developed into SH surface coatings that repel hot water without any limitation to the surface temperature. Our SEM observations demonstrate that nanostructures formed by CNTs, contributing both a high porosity and a small water droplet contact area, will maintain superhydrophobicity even for hot water. In particular, a composite, made of CNTs and an organic silicone resin binder, shows both excellent hot water repellency and mechanical robustness, which, together, promise potential applications in hot liquid self-cleaning and high efficiency heat transfer. 11the surface of sample 2 as a function of water pressure (2 min intervals at each pressure). Figure 10b shows the CA and SA as a function of water jet flow time at 200 kPa. The results show excellent waterfall resistance, compared to what was previously reported [11] . The mechanical durability, resistance abrasion value is close to that of the Ever Ultra-Dry waterproof coating, a commercial product [13] (also see Figure S6 of the supporting information). ConclusionsWe have shown the ability to control surface roughness, especially at the nanoscale, so as to maintain water repellency at high temperatures. We do this by using CNTs to maintain a minimal contact area and to increase porosity, both of which continue to fulfil their functions at higher temperatures. Thus, it appears that CNT-based coatings are prime candidates for designing SH surfaces that repel hot liquids, for self-cleaning and heat-transfer applications.

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“…This trend is similar to those of the composite SH coatings in our previous study [13] . The difference in the CA values of samples 1 and 2, with the surface temperature, Fig.…”

Section: Resultssupporting

confidence: 91%

supporting

confidence: 59%

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Repelling hot water from superhydrophobic surfaces based on carbon nanotubes

Wan¹,

Yang²,

Sacher

2015

J. Mater. Chem. A

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“…Using a low surface energy material, such as PTFE or PVDF, which will protect the SHS from abrasion 19,20,21,22 , our group introduced nano-and microscale porous structures in PTFE superhydrophobic coatings, improving their anti-abrasion properties 23 .…”

Section: Introductionmentioning

confidence: 99%

Improving the Mechanical Durability of Superhydrophobic Coating by Deposition on to a Mesh Structure

Hu¹,

Yang²,

Sacher³

2017

Preprint

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<p>Superhydrophobic surfaces (SHSs) require a combination of a rough nano- or microscale structured surface topography and a low surface energy. However, its superydrophobicity is easily lost, even under relatively mild mechanical abrasion, when the surface is mechanically weak. Here, we develop a method that significantly increases the mechanical durability of a superhydrophobic surface, by introducing a mesh layer beneath the superhydrophobic layer. The hardness, abrasion distance, flexibility and water-jet impact resistance all increase for the commercially available Ultra-ever Dry superhydrophobic coating. This is attributed to the increased mechanical durability offered by the mesh, whose construction not only increases the porosity of the SHS coating but acts as a third, larger structure, so that the superhydrophobic layer is now composed of a three-level hierarchical structure: the mesh, micropillars and nanoparticles.</p>

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“…[9] Hydrophobicity of a solid surface is a property of a material that is dependent on both the surface energy and surface roughness. [10][11][12] The surface energy is inherent to a material and is therefore difficult to adjust, whereas the surface roughness is much more variable. Recently, superhydrophobic materials have garnered interest not only due to their self-cleaning, but also their anti-fouling, stain-resistant, and ice-repellent properties.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Roughness Periodicity on the Hydrophobic Properties of Surfaces

Toster

Lewis

2015

Aust. J. Chem.

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Hydrophobic films were synthesized with a variety of silica particle sizes ranging from 58 to 1428 nm to investigate the effect of particle size on the contact and sliding angles. While the surface roughness created by varying the particle size did not appear to affect water contact angles, the sliding angles showed a significant monotonic decrease, reducing from 908 to 208. IntroductionSelf-cleaning surfaces have developed since the late 20th century and are comprised of two main types, superhydrophobic and superhydrophillic. A surface is generally considered superhydrophobic if it has a water contact angle (WCA) of greater than 1508 and a sliding angle of less than 108. Superhydrophillic surfaces, which attract water, have a WCA of less than 108, thereby resulting in the droplet spreading across the surface quite rapidly. In both cases, the water rolls or slides off the surface at low angle and high velocity, carrying with it dirt and other contaminants, which is the basis of the self-cleaning property. [1] Materials possessing these properties have significant potential from self-cleaning windows to applications on solar panels and the reflective mirrors used in concentrated thermal and photovoltaic (PV) solar plants, whereby vast arrays of mirrors are used. For example, at the Ivanpah solar tower facility in the Mojave Desert in California, 173 500 mirrors are used over an area of 1417 ha.[2] Depending on the nature, size, and density of coverage, dust accumulation can diminish transmittance and/or reflectance at a rate 7 % per month, with every percentage lost thorough scattering or absorption, thus reducing the efficiency of the plant. [3,4] The result is that these systems require almost constant cleaning in regions where water can be scarce and expensive. To be effective on mirrors, PVs, and windows, the superhydrophobic coatings must be transparent and have both thermal and mechanical durability. [5,6] Nature is the primary inspiration for this technology as researchers have investigated the ability of some plants to self-clean via their hydrophobic properties. [7,8] This is best presented by the lotus leaf, such that the self-cleaning phenomenon of superhydrophobicity is referred as the 'Lotus Effect'. [9] Hydrophobicity of a solid surface is a property of a material that is dependent on both the surface energy and surface roughness. [10][11][12] The surface energy is inherent to a material and is therefore difficult to adjust, whereas the surface roughness is much more variable. Recently, superhydrophobic materials have garnered interest not only due to their self-cleaning, but also their anti-fouling, stain-resistant, and ice-repellent properties. [13][14][15] Superhydrophobic materials are fabricated through various approaches such as chemical vapour deposition, templating, chemical etching, self-assembly, sol-gel, and electrospinning. [16][17][18][19][20][21][22] One particular method demonstrated by Tserepi et al. involved plasma treatment of polydimethylsiloxane (PDMS) in SF 6 gas to form superh...

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Durable superhydrophobic PTFE films through the introduction of micro- and nanostructured pores

Cited by 60 publications

References 46 publications

Repelling hot water from superhydrophobic surfaces based on carbon nanotubes

Repelling hot water from superhydrophobic surfaces based on carbon nanotubes

Improving the Mechanical Durability of Superhydrophobic Coating by Deposition on to a Mesh Structure

Investigation of Roughness Periodicity on the Hydrophobic Properties of Surfaces

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