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(a) Optical images show the micro-dynamic behaviour of the fog drops movement on the PF coupled with sprayed SiO2 coatings and the MPA surface. From t = 0 s to t = 90 s, as the fog drops (A–E) grow larger gradually (t = 20 s), they will merge with each other, fog drops B and C coalesce into larger fog drop F (t = 30 s), fog drops D and E coalesce into larger fog drop H (t = 45 s) and fog drops A and F coalesce into larger droplet I (t = 55 s). Then, fog drops H and I merge with fog drop G and form fog drop J (t = 90 s). (b) Time evolution of the diameter of an individual fog drop during the merge process (blue triangles). The inserts correspond to t = 20, 30, 45, 55 and 90 s. (c) Additional details are displayed with the assistance of schematic diagrams
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In this work, inspired by some typical creatures from nature with superhydrophobic surfaces, a bio-inspired antifogging PDMS is designed and fabricated successfully using UV lithography and a template method. First, we fabricated an SU-8 layer with a bio-inspired micro-pillared array (MPA) using traditional UV lithography. Then, it was used as a te...
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... Since the discovery of the lotus leaf effect [17], superhydrophobic materials with high water repellency abilities can achieve self-cleaning [18], anti-corrosion [19], antibiofouling [20], anti-fogging [21], oil-water separation [22], and so on. Preparation of superhydrophobic materials with oil-water separation ability has become a research topic. ...
Oil–water separation using special wettability materials has received much attention due to its low energy consumption and high separation efficiency. Herein, a fluorine-free superhydrophobic cotton fabric (PDMS/STA-coated cotton fabric) was successfully prepared by a simple impregnation method using hydroxyl-capped polydimethylsiloxane (PDMS-OH), tetraethoxysilane (TEOS), and stearic acid (STA) as precursors. The investigation found that the cross-linking reactions between the hydroxyl groups of PDMS-OH and hydrolyzed TEOS enabled a strong interaction between PDMS-OH and cotton fabric. Furthermore, a suitable roughness surface of coated cotton fabric was established by introducing STA due to its long chain structure. The contact angle of this composite can reach 158.7° under optimal conditions due to its low surface energy and desired roughness. The oil/water separation efficiency of PDMS/STA-coated cotton fabric is higher than 90% even after 10 cycles of oil–water separation, and the oil flux can reach 11862.42 L m−2 h−1. In addition, PDMS/STA-coated cotton fabric exhibits excellent chemical stability and durability under extreme conditions such as strong acid (HCl, pH = 1~2) and alkali (NaOH, pH = 13~14), and the hydrophobicity of PDMS/STA-coated cotton fabric was decreased to 147° after 300 cycles of abrasion testing.
... The final superhydrophobic surfaces prepared by the authors achieved a contact angle of 155.4 ± 0.5 • and excellent surfaces in terms of anti-icing. Han et al. reported a combination of UV curing and the template method to prepare superhydrophobic surfaces with a good anti-fogging effect [66]. A negative photoresist SU-8 was spin-coated on a clean slide and a template containing a circular array was photolithographed. ...
... 2020, Langmuir (b) Schematic diagram of the preparation process of PDMS. Reprinted with permission from Ref.[66]. 2018, RSC Adv. ...
As research on superhydrophobic materials inspired by the self-cleaning and water-repellent properties of plants and animals in nature continues, the superhydrophobic preparation methods and the applications of superhydrophobic surfaces are widely reported. Silicones are preferred for the preparation of superhydrophobic materials because of their inherent hydrophobicity and strong processing ability. In the preparation of superhydrophobic materials, silicones can both form micro-/nano-structures with dehydration condensation and reduce the surface energy of the material surface because of their intrinsic hydrophobicity. The superhydrophobic layers of silicone substrates are characterized by simple and fast reactions, high-temperature resistance, UV resistance, and anti-aging. Although silicone superhydrophobic materials have the disadvantages of relatively low mechanical stability, this can be improved by the rational design of the material structure. Herein, we summarize the superhydrophobic surfaces made from silicone substrates, including the cross-linking processes of silicones through dehydration condensation and hydrosilation, and the surface hydrophobic modification by grafting hydrophobic silicones. The applications of silicone-based superhydrophobic surfaces have been introduced such as self-cleaning, corrosion resistance, oil–water separation, etc. This review article should provide an overview to the bioinspired superhydrophobic surfaces of silicone-based materials, and serve as inspiration for the development of polymer interfaces and colloid science.
... 9,11,12 Superhydrophobic surfaces are also interesting as bio-inspired artificial analogues which exhibit other functional surface properties such as water repellence, anti-fog, anti-icing, reduced adhesion and antibiofouling properties. 6,[13][14][15][16][17][18] Multiple approaches have been employed to design superhydrophobic surfaces demonstrating a necessary combination of the appropriate roughness and chemical properties such as lithography and templating methods, plasma treatments, various deposition methods, as well as completely different strategy based on slippery liquidinfused porous surfaces (SLIPS). 19,[20][21][22][23] Most of these fabrication routes are complicated, expensive or limited to specific materials and final usage purposes. ...
Superhydrophobcity is a well-known wetting phenomenon found in numerous plants and insects. It is achieved by the combination of the surfaces chemical properties and its surface roughness. Inspired by nature, numerous synthetic superhydrophobic surfaces have been developed for various applications. Designated surface coating is one of the fabrication routes to achieve the superhydrophobicity. Yet, many of these coatings, such as fluorine-based formulations, may pose severe health and environmental risks, limiting the applicability. Herein, we present a new family of superhydrophobic coatings comprised of natural saturated fatty acids, which are not only a part of our daily diet, but can be produced from renewable feedstock, providing a safe and sustainable alternative to existing state-of-the-art. These crystalline coatings are readily fabricated via single-step deposition routes, thermal deposition or spray-coating. The fatty acids self-assemble into highly hierarchical crystalline structures exhibiting a water contact angle of about 165 degrees and contact angle hysteresis lower than 6 degrees, while their properties and morphology depend on the specific fatty acid used as well as on the deposition technique. Moreover, the fatty acid coatings demonstrate excellent thermal stability. Importantly these new family of coatings displays excellent anti-biofouling and antimicrobial properties against Escherichia coli and Listeria innocua, used as relevant model Gram-negative and Gram-positive bacteria, respectively. We believe that these coatings have a great application potential in the fields, where other alternatives are prohibited due to safety limitations, while at the same time their usage in other regulation-free applications is not limited.
... Sun等人 [14] 采用电化学刻蚀和氟化处理 的方法, 在铝板表面得到具有超疏水性能的矩形微柱 阵列. Han等人 [15] 利用紫外光刻技术制备具有超疏水 和防雾性能的微柱阵列. 然而, 这些微纳结构主要通过 光刻或化学刻蚀的方法制备, 存在加工过程复杂、容 易造成环境污染等缺点 [16] . ...
... 31,32 Superhydrophobicity of PDMS medical devices can be achieved through several techniques such as micropatterning of surfaces and coating fabrication. 33,34 Spray coating is one of the simple methods as a number of chemicals can be deposited once or in a repeated way on PDMS. 28,35 However, maintaining the durability of the coatings on PDMS is important for prolonged usage of catheters. ...
Crystalline biofilm formation in indwelling urinary catheters is a serious health problem as it creates a barrier for antibacterial coatings. This emphasizes the failure of antibacterial coatings that do not have a mechanism to reduce crystal deposition on catheter surfaces. In this study, trifluoropropyl spray-coated polydimethylsiloxane (TFP–PDMS) has been employed as an antibiofilm forming surface without any antibacterial agent. Here, TFP was coated on half-cured PDMS using the spray coating technique to obtain a durable superhydrophobic coating for a minimum five cycles of different sterilization methods. The crystalline biofilm-forming ability of Proteus mirabilis in artificial urine, under static and flow conditions, was assessed on a TFP-PDMS surface. In comparison to the commercially available silver-coated latex and silicone catheter surfaces, TFP–PDMS displayed reduced bacterial attachment over 14 days. Moreover, the elemental analysis determined by atomic absorption spectroscopy and energy-dispersive X-ray analysis revealed that the enhanced antibiofilm forming ability of TFP-PDMS was due to the self-cleaning activity of the surface. We believe that this modified surface will significantly reduce biofilm formation in indwelling urinary catheters and further warrant future clinical studies.
... To date, different techniques have been reported to fabricate SHS, including laser method, 14, 39 chemical method, [16][17][18]40 electrochemical method, 16,17 wire electrical discharge machining, 41 3D printing method, 21, 42 template method 23,43 and coating method 44,45 . Although the fabricated SHS with different micro-morphologies all showed excellent water-repellency (more details are shown in Supporting Information), features like accuracy and efficiency should be emphasized when choosing a specific method to fabricate SHS for energy conversion. ...
Covering about 70% of the earth's surface, water contains considerable energy that remains unexploited. Superhydrophobic surface (SHS) possesses excellent water repellency, and the energy conversion based on SHS has opened up a new venue for efficient collecting and utilizing of water energy. Therefore, it is of great significance to efficiently prepare SHS and apply it for energy conversion in different fields. In this review, we first summarize the fabrication methods of SHS, and then provide an overview of the energy conversion forms based on SHS. Finally, the related applications corresponding to the energy conversion forms are introduced, including renewable energy collection and utilization, wearable device design, use of liquid sensors, surface cooling and heat dissipation, self-propelled device, droplet manipulation and lab-on-a-chip device; and their challenges and future perspectives are highlighted.
... The refractive of SiO2 is about 1.45, which is close to that of glass. SiO2 film is often used as transparent anti-fogging materials [5,6]. ...
TiO 2 , SiO 2 and TiO 2 -SiO 2 thin films were prepared by sol-gel dipping method on glass substrates. The pyrolysis behavior of TiO 2 and SiO 2 dry gel were tested by differential thermal analysis (DTA). The microstructure and optical properties of the TiO 2 , SiO 2 and TiO 2 - SiO 2 were studied by X-ray diffraction (XRD) and ultraviolet and visible spectrophotometer. The results showed that the phase structure of the films was affected by the composition. All the films were transparent in the visible region. Meanwhile, the transparency of SiO 2 was better than TiO 2 and TiO 2 -SiO 2 composite film. The ban-gap of the TiO 2 , SiO 2 and TiO 2 -SiO 2 thin films were 3.79, 4.01 and 3.91.
Owing to its hydrophobic nature, polymers are more commonly employed to impart superhydrophobicity over different surfaces. This review gives a brief account on the theories behind superhydrophobicity and techniques employed to develop superhydrophobic coatings over metal, fabrics, papers, sponges, foam, glass, wood, mesh, concrete and ceramic surfaces. Fine‐tuning of superhydrophobic polymeric surfaces is much required to enhance corrosion control, oil‐water separation, self‐cleaning, drag reduction, anti‐microbial, anti‐bio‐fouling, anti‐icing and desalination properties. Methodology and current developments in the designing such superhydrophobic polymeric surfaces are highlighted. To conclude, the challenges to be addressed by the scientific world to solve the problems associated with mass production, stability and durability of the coatings, development of hierarchical micro‐nanostructures are detailed.
Poly(dimethylsiloxane) (PDMS) has been widely employed in biomedical disciplines due to its several advantages, including biocompatibility, nontoxicity, and low‐cost preparation. However, the intrinsic hydrophobicity of this material encourages biofouling and reduces cell regulation capacity, thereby limiting its biomedical applicability. The purpose of this study is to explore the surface modification and functionalization of PDMS and PDMS‐based biomaterials to improve their properties for biomedical applications. The content of this review is organized based on physical and chemical surface modification strategies to improve surface hydrophilicity to enhance antibiofouling and the regulation of immunomodulation and cell modulation on the surface of PDMS and PDMS‐based biomaterials. Future developments in this area are also discussed. Poly(dimethylsiloxane)‐based medical materials are being used extensively in biomedical applications and various biomimetic strategies are developed for meeting various complex functional needs. Herein, the limitations of PDMS‐based medical materials and the currently used approaches for surface hydrophilic modification and functionalization to overcome them are reviewed. Advanced biomimetic devices with multibiocompatible functional properties are a future research trend.
Superhydrophobicity is a well-known wetting phenomenon found in numerous plants and insects. It is achieved by the combination of the surface's chemical properties and its surface roughness. Inspired by nature, numerous synthetic superhydrophobic surfaces have been developed for various applications. Designated surface coating is one of the fabrication routes to achieve the superhydrophobicity. Yet, many of these coatings, such as fluorine-based formulations, may pose severe health and environmental risks, limiting the applicability. Herein, we present a new family of superhydrophobic coatings comprised of natural saturated fatty acids, which are not only a part of our daily diet, but can be produced from renewable feedstock, providing a safe and sustainable alternative to existing state-of-the-art. These crystalline coatings are readily fabricated via single-step deposition routes, thermal deposition or spray-coating. The fatty acids self-assemble into highly hierarchical crystalline structures exhibiting a water contact angle of ∼165° and contact angle hysteresis lower than 6°, while their properties and morphology depend on the specific fatty acid used as well as on the deposition technique. Moreover, the fatty acid coatings demonstrate excellent thermal stability. Importantly these new family of coatings display excellent anti-biofouling and antimicrobial properties against Escherichia coli and Listeria innocua, used as relevant model Gram-negative and Gram-positive bacteria, respectively. These multifunctional coatings hold immense potential for application in numerous fields, ranging from food safety to biomedical, offering sustainable and safe solutions.
