Superhydrophobic Tensile Designability of Silicone Rubber Composites

Silicone rubber has broad applications in the field of industrial engineering due to its stable physical and chemical properties. However, the superhydrophobic properties, of silicone rubber, especially large deformation superhydrophobic properties, were not satisfactory for many harsh application environments and complex engineering structures. Here, we report the preparation of superhydrophobic tensile designable silicone rubber composites by a mixed deposition process that included powder deposition and smoke deposition. The infrared test showed that the deposited powder from silicone rubber combustion was mainly composed of SiO2 and short chain siloxane. The mixed deposited surface with a rich micro-nanostructure, which was the key to the formation of superhydrophobic properties. The water contact angle (WCA) and sliding angle (SA) of coating surface could reach 157.6° and 5° ± 1°, respectively, and the tensile designability of superhydrophobic surface is closely related to the prestretched process. In addition, bounce tests, high temperature tests, and solvent resistance tests showed the application potential of modified silicone rubber composites in the field of engineering.

Observing Real-Time Adhesion of Microparticles on Glass Surfaces

Fouling on glass surfaces reduces the solar panel efficiency and increases water consumption for cleaning. Superhydrophobic coatings on glass enable self-cleaning by allowing water droplets to carry away dirt particles. Observing the interaction between charged particles and surfaces provides insights into effective cleaning. Using a high-speed camera and a long-distance objective, we analyzed the in situ deposition of variously functionalized and charged silica dust microparticles on chemically treated glass. The ambient charges for the control, hydrophobic, and positively charged particles were approximately -0.5, -0.13, and +0.5 nC, respectively. We found that a positively charged particle of 2.3 ± 1.2 μm diameter adhered to hydroxylated glass in ∼0.054 s, compared to 0.40 and 0.45 s for quaternary ammonium- and fluorosilane-functionalized hydrophobic glass. Experiments suggest that quaternary ammonium-functionalized glass surfaces are about 77.8% more resistant to soiling than bare surfaces.

Structure, preparation and properties of liquid fluoroelastomers with different end groups

In order to design and prepare liquid fluoroelastomers with different end groups, and reveal the relationship between the molecular chain structure and properties, we studied on the oxidation degradation method and functional group conversion method to prepare carboxyl-terminated and hydroxyl-terminated liquid fluoroelastomers, respectively. The reaction mechanisms were also deduced. Furthermore, the curing system was created for liquid fluoroelastomers, and systematically analyzed their properties. The sequence type and content of the -C[double bond, length as m-dash]C- and oxygen-containing groups in the samples were measured and characterized by attenuated total reflectance/Fourier transform infrared (ATR-FTIR) spectroscopy, 1H nuclear magnetic resonance (1H-NMR), 19F-NMR spectroscopy and chemical titration, the molecular weights of liquid fluoroelastomers were measured by gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to examine the thermal properties, while a viscometer was used to measure the dynamic viscosity of the liquid fluoroelastomers. Then the mechanical and surface properties of the cured samples were examined by universal testing machine and contact angle measurement instrument, respectively. The results show that carboxyl-terminated liquid fluoroelastomer with 2.71 wt% carboxyl terminal groups can be prepared by oxidation degradation method. When lithium aluminium hydride (LiAlH4) was used as the reducing agent, it can efficiently convert carboxyl group to hydroxyl group with a conversion rate of more than 95%. In addition, it can be seen that the dynamic viscosity of the liquid fluoroelastomers were all decreased with the increase of temperature, and it is similar to about 10 Pa s at 70 °C. Compared with carboxyl-terminated liquid fluoroelastomers, hydroxyl-terminated liquid fluoroelastomers has higher curing reactivity, higher glass transition temperature (T g) and thermal decomposition temperature (T d), and better mechanical properties of cured samples. The two types of liquid fluoroelastomers with distinct end groups presented distinct hydrophilicity.

Porous Layer-by-Layer Films Assembled Using Polyelectrolyte Blend to Control Wetting Properties

Porous layer-by-layer (LbL) films have been employed for the implementation of superwetting surfaces, but they are limited to the LbL films consisting of only two oppositely charged polyelectrolytes. In this study, LbL films were assembled using a cationic polymer blend of branched poly(ethylene imine) (BPEI) and poly(allylamine hydrochloride) (PAH), and anionic poly(acrylic acid); they were then acid-treated at pH 1.8-2.0 to create a porous structure. The films of 100% BPEI exhibited a relatively smooth surface, whereas those of the 100% PAH exhibited porous surfaces. However, various surface morphologies were obtained when BPEI and PAH were blended. When coated with fluorinated silane, films with 50% and 100% PAH exhibited relatively higher water contact angles (WCAs). In particular, films with 50% PAH exhibited the highest WCA of 140-150° when treated at pH 1.8. These fluorinated films were further infused with lubricant oil to determine their feasibility as slippery surfaces. The water and oil sliding angles were in the range of 10-20° and 5-10°, respectively. Films prepared with the BPEI/PAH blend showed lower water slide angles than those prepared with 100% BPEI or PAH. Acid treatment of LbL films assembled using a polyelectrolyte blend can effectively control surface morphologies and can potentially be applied in superwetting.

UV-LED as a New Emerging Tool for Curable Polyurethane Acrylate Hydrophobic Coating

The elimination of mercury, low energy consumption, and low heat make the ultraviolet light-emitting diode (UV-LED) system emerge as a promising alternative to conventional UV-mercury radiation coating. Hence, a series of hydrophobic coatings based on urethane acrylate oligomer and fluorinated monomer via UV-LED photopolymerisation was designed in this paper. The presence of fluorine component at 1160 cm-1, 1235 cm-1, and 1296 cm-1 was confirmed by Fourier Transform Infra-Red spectroscopy. A considerably high degree C=C conversion (96-98%) and gel fraction (95-93%) verified the application of UV-LED as a new technique in radiation coating. It is well-accepted that fluorinated monomer can change the surface wettability as the water contact angle of the coating evolved from 88.4° to 121.2°, which, in turn, reduced its surface free energy by 70.5%. Hence, the hydrophobicity of the coating was governed by the migration of the fluorine component to the coating surface as validated by scanning electron and atomic force microscopies. However, above 4 phr of fluorinated monomer, the transparency of the cured coating examined by UV-visible spectroscopy experienced approximately a 16% reduction. In summary, the utilisation of UV-LED was a great initiative to develop green aspect in photopolymerisation, particularly in coating technology.

Silicone Surface Fundamentals

Many of the applications of the most familiar silicone polymer, polydimethylsiloxane (PDMS), are a consequence of its hydrophobic nature. The key quantities underlying this behavior are the water contact angle with water droplets, the surface tension of the polymer, and its interfacial tension with water. These quantities are reviewed for PDMS and the fluorsilicone polymethyltrifluoropropylsiloxane (PMTFPS) as well as some other less common, more highly fluorinated, fluorosilicones. As aliphatic fluorocarbons are usually introduced into polymers to lower surface tension, it is unexpected that the surface tension of PMTFPS is higher than PDMS. However, this observation is consistent with Zisman's early extensive studies. It is also somewhat surprising that there are no definitive values accepted for the water contact angle with PDMS and the interfacial tension at the PDMS/water interface. Some reasons for this are explored and relevant limitations considered. The variety of ways in which a PDMS surface can be presented must have a major effect on the range of water contact angles reported.

Rapid and Stable Plasma Transformation of Polyester Fabrics for Highly Efficient Oil-Water Separation

Fabrics with special wettability have drawn growing attention in recent years in the area of oil-water separation due to their low cost, good flexibility, and ease of handling. However, an efficient and fast method to enable the required wetting state on fabrics still remains a challenge. In this work, a one-step, rapid, and chemical-free hydrogen plasma treatment is reported to prepare a superhydrophobic and oleophilic polyester fabric. The as-prepared fabrics display a static water contact angle of 153.2° with excellent oil-water separation capability. The mechanism of surface transformation is discussed through chemical analyses, which indicate a significant removal of carboxyl group from the pristine hydrophilic surface. This developed method is envisaged to be used for on-demand large-scale production of materials for emergency oil cleanup through either separation or selective adsorption.

The fabrication of mechanically durable and stretchable superhydrophobic PDMS/SiO2 composite film

Stretchable superhydrophobic film was fabricated by casting silicone rubber polydimethylsiloxane (PDMS) on a SiO₂ nanoparticle-decorated template and subsequent stripping. PDMS endowed the resulting surface with excellent flexibility and stretchability. The use of nanoparticles contributed to the sustained roughening of the surface, even under large strain, offering mechanically durable superhydrophobicity. The resulting composite film could maintain its superhydrophobicity (water contact angle ≈ 161° and sliding angle close to 0°) under a large stretching strain of up to 100% and could withstand 500 stretching–releasing cycles without losing its superhydrophobic properties. Furthermore, the obtained film was resistant to long term exposure to different pH solutions and ultraviolet light irradiation, as well as to manual destruction, sandpaper abrasion, and weight pressing.

Stretchable superhydrophobic film was fabricated by casting silicone rubber polydimethylsiloxane (PDMS) on a SiO₂ nanoparticle-decorated template and subsequent stripping.

Fabrication of superhydrophobic coatings with self-cleaning properties on cotton fabric based on Octa vinyl polyhedral oligomeric silsesquioxane/polydimethylsiloxane (OV-POSS/PDMS) nanocomposite

HYPOTHESIS

Wetting behavior of solid surfaces plays an important role in various industrials and even daily life applications. Controlling the surface wettability through fabricating strongly hydrophilic or hydrophobic properties is achieved by tailoring surface topography and chemical composition. Polyhedral oligomeric silsesquioxanes (POSSs) are a class of hybrid materials with the possibility of hydrophobicity enhancement through simultaneous increase in surface roughness and reduction of surface energy.

EXPERIMENTS

In this study, octavinyl-POSS (OV-POSS) structures were utilized in fabrication of superhydrophobic cotton fabric. Coating was successfully performed through creating a two-layer topography via spraying method. In brief, surface roughness was enhanced by spraying a base layer of TiO₂ sol over the surface followed by applying a nanocomposite layer composed of 0.02 wt% of POSS in polydimethylsiloxane (PDMS).

FINDINGS

It was observed that, water contact angle (WCA) of pristine and TiO₂ coated fabric was enhanced from 0° up to ∼168° using 0.02 wt% OV-POSS/PDMS nanocomposite with a water sliding angle (WSA) of <10°. According to the results, environmentally friendly nature of precursors, high thermal, mechanical and chemical stability, self-cleaning and anti-adhesion propertiesof the as-prepared coating and simple preparation method with no special post-treatment requirement, confirm that the as-prepared coating is perfect candidate for large-scaled applications.

Preparation and characterization of POSS-containing poly(perfluoropolyether)methacrylate hybrid copolymer and its superhydrophobic coating performance

To design a mechanically stable and superhydrophobic coating, a polyhedral oligomeric silsesquioxane (POSS)-containing poly(perfluoropolyether)methacrylate (PFPEM) hybrid copolymer (PFPEM–POSS) was synthesized via a free-radical solution polymerization with PFPEM, 1H,1H,2H,2H-perfluorooctyl acrylate, methyl (meth)acrylate, n-butyl acrylate, hydroxypropyl acrylate, methacryloxy propyl trimethoxy silane, and methacrylisobutyl POSS; and azobisisobutyronitrile as an initiator. Hydrophobic coatings were formed on substrates by a facile one-step dip-coating method in a solution mixture of diethylene glycol dimethyl ether with the PFPEM–POSS hybrid copolymer. The chemical structure of the PFPEM–POSS copolymer and the surface morphology and performance of the PFPEM–POSS coatings were investigated. The results indicate that, under POSS aggregation via the fluorophilic/oleophilic co-monomer phase separation and owing to the low-surface-energy poly(perfluoropolyether)methacrylate incorporated into the copolymer, PFPEM–POSS exhibited a hierarchical micro-nano roughness in atomic force microscopy observations and provided the treated substrates with excellent hydrophobicity and abrasion resistance. As a result, the water contact angle reached 152.3° on the treated glass.

A coating with excellent superhydrophobicity and durability was built via incorporating an environmentally-friendly poly(perfluoropolyether)methacrylate copolymer into polyhedral oligomeric silsesquioxane (POSS).

An insight into the amphiphobicity and thermal degradation behavior of PDMS-based block copolymers bearing POSS and fluorinated units

Methacryloxypropyl-polyhedral oligomeric silsesquioxane (MAPOSS) and dodecafluoroheptyl methacrylate (DFHM) are proposed to separately block-copolymerize with polydimethylsiloxane (PDMS)-based acrylate block copolymer (PDMS-b-PMMA). The syntheses of PDMS-b-PMMA-b-PMAPOSS and PDMS-b-PMMA-b-PDFHM were executed in this manner to examine the effect of PMAPOSS and PDFHM on surface amphiphobic behavior and thermal degradation behavior. PMAPOSS and PDFHM were found to both contribute towards the improvement of static hydrophobicity. However, the PMAPOSS was found to disable the dynamic hexadecane-dewetting properties because of its restriction on molecular wriggling motion and its induced high roughness. In contrast, PDFHM was found to improve the dynamic dewetting properties for oil-based ink. With regard to the thermal stability, the incorporation of either PMAPOSS or PDFHM into PDMS-b-PMMA with PDMS (Mn ∼1000 or 5000 Da) favors the increase in the original thermal-decomposition temperature. However, the presence of PMAPOSS initiates a higher degradation rate and fails to improve the thermal stability in the case of long PDMS (Mn ∼10 000 Da) due to the heterogeneous dispersion of POSS in the matrix.

Rational design of materials interface at nanoscale towards intelligent oil-water separation

Oil-water separation is critical for the water treatment of oily wastewater or oil-spill accidents. The oil contamination in water not only induces severe water pollution but also threatens human beings' health and all living species in the ecological system. To address this challenge, different nanoscale fabrication methods have been applied for endowing biomimetic porous materials, which provide a promising solution for oily-water remediation. In this review, we present the state-of-the-art developments in the rational design of materials interface with special wettability for the intelligent separation of immiscible/emulsified oil-water mixtures. A mechanistic understanding of oil-water separation is firstly described, followed by a summary of separation solutions for traditional oil-water mixtures and special oil-water emulsions enabled by self-amplified wettability due to nanostructures. Guided by the basic theory, the rational design of interfaces of various porous materials at nanoscale with special wettability towards superhydrophobicity-superoleophilicity, superhydrophilicity-superoleophobicity, and superhydrophilicity-underwater superoleophobicity is discussed in detail. Although the above nanoscale fabrication strategies are able to address most of the current challenges, intelligent superwetting materials developed to meet special oil-water separation demands and to further promote the separation efficiency are also reviewed for various special application demands. Finally, challenges and future perspectives in the development of more efficient oil-water separation materials and devices by nanoscale control are provided. It is expected that the biomimetic porous materials with nanoscale interface engineering will overcome the current challenges of oil-water emulsion separation, realizing their practical applications in the near future with continuous efforts in this field.

A Highly Stretchable and Robust Non-fluorinated Superhydrophobic Surface

Superhydrophobic surface simultaneously possessing exceptional stretchability, robustness, and non-fluorination is highly desirable in applications ranging from wearable devices to artificial skins. While conventional superhydrophobic surfaces typically feature stretchability, robustness, or non-fluorination individually, co-existence of all these features still remains a great challenge. Here we report a multi-performance superhydrophobic surface achieved through incorporating hydrophilic micro-sized particles with pre-stretched silicone elastomer. The commercial silicone elastomer (Ecoflex) endowed the resulting surface with high stretchability; the densely packed micro-sized particles in multi-layers contributed to the preservation of the large surface roughness even under large strains; and the physical encapsulation of the microparticles by silicone elastomer due to the capillary dragging effect and the chemical interaction between the hydrophilic silica and the elastomer gave rise to the robust and non-fluorinated superhydrophobicity. It was demonstrated that the as-prepared fluorine-free surface could preserve the superhydrophobicity under repeated stretching-relaxing cycles. Most importantly, the surface's superhydrophobicity can be well maintained after severe rubbing process, indicating wear-resistance. Our novel superhydrophobic surface integrating multiple key properties, i.e. stretchability, robustness, and non-fluorination, is expected to provide unique advantages for a wide range of applications in biomedicine, energy, and electronics.

Influence of carbonization temperature and press processing on the electrochemical characteristics of self-standing iron oxide/carbon composite electrospun nanofibers

Schematic illustration of self-standing active material composite carbon nanofibrous electrodes for lithium ion battery applications.

Interfacial behaviour of cubic silsesquioxane and silica nanoparticles in Langmuir and Langmuir–Blodgett films

Fluorinated polyhedral oligomeric silsesquioxanes (POSS) have been established as useful for the fabrication of superhydrophobic coatings, however little attention has been paid to their use for making ultrathin film by the Langmuir–Blodgett method.

Poly(triphenyl ethene) and poly(tetraphenyl ethene): synthesis, aggregation-induced emission property and application as paper sensors for effective nitro-compounds detection

This paper reports two structurally unique aggregation-induced emission (AIE) polymers that are fully constructed by AIE luminogen tetraphenyl or triphenyl ethene units. Their applications as paper sensors are studied.

Fabrication of a micro-nanostructured superhydrophobic aluminum surface with excellent corrosion resistance and anti-icing performance

Synergy is the key to realizing superhydrophobicity. The as-prepared superhydrophobic Al surface possesses both excellent corrosion resistance and anti-icing performance.

Electrospun nanofiber SLIPS exhibiting high total transparency and scattering

Antifouling coatings are important in fields such as mobility, architecture, power generation devices, and medical devices, where energy efficiency is required to be maximized.

Superhydrophobic nanocoatings: from materials to fabrications and to applications

Superhydrophobic nanocoatings, a combination of nanotechnology and superhydrophobic surfaces, have received extraordinary attention recently, focusing both on novel preparation strategies and on investigations of their unique properties. In the past few decades, inspired by the lotus leaf, the discovery of nano- and micro-hierarchical structures has brought about great change in the superhydrophobic nanocoatings field. In this paper we review the contributions to this field reported in recent literature, mainly including materials, fabrication and applications. In order to facilitate comparison, materials are divided into 3 categories as follows: inorganic materials, organic materials, and inorganic-organic materials. Each kind of materials has itself merits and demerits, as well as fabrication techniques. The process of each technique is illustrated simply through a few classical examples. There is, to some extent, an association between various fabrication techniques, but many are different. So, it is important to choose appropriate preparation strategies, according to conditions and purposes. The peculiar properties of superhydrophobic nanocoatings, such as self-cleaning, anti-bacteria, anti-icing, corrosion resistance and so on, are the most dramatic. Not only do we introduce application examples, but also try to briefly discuss the principle behind the phenomenon. Finally, some challenges and potential promising breakthroughs in this field are also succinctly highlighted.

Multiscale ommatidial arrays with broadband and omnidirectional antireflection and antifogging properties by sacrificial layer mediated nanoimprinting

Moth's eye inspired multiscale ommatidial arrays offer multifunctional properties of great significance in optoelectronic devices. However, a major challenge remains in fabricating these arrays on large-area substrates using a simple and scalable technique. Here we present the fabrication of these multiscale ommatidial arrays over large areas by a distinct approach called sacrificial layer mediated nanoimprinting, which involves nanoimprinting aided by a sacrificial layer. The fabricated arrays exhibited excellent pattern uniformity over the entire patterned area. Optimum dimensions of the multiscale ommatidial arrays determined by the finite-difference time domain simulations served as the design parameters for replicating the arrays on glass. A broadband suppression of reflectance to a minimum of ∼1.4% and omnidirectional antireflection for highly oblique angles of incidence up to 70° were achieved. In addition, superhydrophobicity and superior antifogging characteristics enabled the retention of optical properties even in wet and humid conditions, suggesting reliable optical performance in practical outdoor conditions. We anticipate that these properties could potentially enhance the performance of optoelectronic devices and minimize the influence of in-service conditions. Additionally, as our technique is solely nanoimprinting-based, it may enable scalable and high-throughput fabrication of multiscale ommatidial arrays.

Fluorous Cylindrical Micelles of Controlled Length by Crystallization-Driven Self-Assembly of Block Copolymers in Fluorinated Media

Fluorous solvents have recently found broad applications in medical treatments as well as catalytic transformations, yet the controlled self-assembly of nanomaterials in fluorinated media has remained a challenge. Herein, we report the synthesis of block copolymers containing a crystalline polyferrocenylsilane metalloblock and a highly fluorinated coil block and their controlled self-assembly in fluorinated media. Using the crystallization-driven self-assembly approach, cylindrical micelles have been prepared with controlled lengths and narrow length polydispersities by self-seeding. Finally, by partial functionalization of these block copolymers with fluorescent dye molecules, we show that well-defined, functional nanomaterials can be obtained in the fluorous phase.

Controlled synthesis of amphiphilic graft copolymer for superhydrophobic electrospun fibres with effective surface fluorine enrichment: the role of electric field and solvent

Ultra-high surface fluorine enriched superhydrophobic fibrous films have been realized by electrospinning amphiphilic graft PMMA-r-PHPA-g-PDFMA, which is ascribed to the electric field and solvent.

POSS-tethered fluorinated diblock copolymers with linear- and star-shaped topologies: synthesis, self-assembled films and hydrophobic applications

Polyhedral oligomeric silsesquioxane (POSS) tethered fluorinated diblock copolymers are synthesized using octakis(dibromoethyl)POSS and aminopropylisobutyl POSS initiation of methylmethacrylate and dodecafluoroheptylmethacrylate.

Poly (vinylidene fluoride) / Poly (acrylonitrile)-based Superior Hydrophobic Piezoelectric Solid Derived by Aligned Carbon Nanotube in Electrospinning: Fabrication, the Phase Conversion and Surface Energy

Multifunctional materials have attracted many interests from both fundamental and practical aspects, such as field-effect transistor, electric protection, transducers and biosensor. Here we demonstrated the first superior hydrophobic piezoelectric surface based on the polymer blend of polyvinylidene fluoride (PVDF)-polyacrilonitrile (PAN) assisted with functionalized multiwalled nanotubes (MWNTs), by a modified electrospinning method. Typically the β-phase polyvinylidene fluoride (PVDF) was considered as the excellent piezoelectric and pyroelectric materials. However, polar β-phase of PVDF exhibited a natural high hydrophilicity. As a well-known fact, the wettability of the surface is dominated by two major factors: surface composition and surface roughness. The significant conversions derived by the incorporation of MWNTs, from nonpolar α-phase to highly polar β-phase of PVDF, were confirmed by FTIR. Meanwhile, the effects of MWNTs on the improvement of the roughness and the hydrophobicity of polymer blend were evaluated by atomic force microscopy (AFM) and contact angle (CA). Molar free energy of wetting of the polymer nanocomposite decreases with increasing the wt.% of MWNTs. All molar free energy of wetting of PVDF-PAN/MWNTs were negative, which means the non-wettability of film. The combination of surface roughness and low-surface-energy modification in nanostructured composites leads to high hydrophobicity. Particularly, fabrication of superior hydrophobic surfaces not only has fundamental interest but also various possible functional applications in micro- and nano-materials and devices.

A nanocellular PVDF–graphite water-repellent composite coating

We have developed a cost-effective method for the preparation of a porous superhydrophobic polyvinylidene fluoride (PVDF)/graphite composite with an induced nanocellular patterned surface.

Chemically stable and mechanically durable superamphiphobic aluminum surface with a micro/nanoscale binary structure

We developed a simple fabrication method to prepare a superamphiphobic aluminum surface. On the basis of a low-energy surface and the combination of micro- and nanoscale roughness, the resultant surface became super-repellent toward a wide range of liquids with surface tensions of 25.3-72.1 mN m(-1). The applied approach involved (1) the formation of an irregular microplateau structure on an aluminum surface, (2) the fabrication of a nanoplatelet structure, and (3) fluorination treatment. The chemical stability and mechanical durability of the superamphiphobic surface were evaluated in detail. The results demonstrated that the surface presented an excellent chemical stability toward cool corrosive liquids (HCl/NaOH solutions, 25 °C) and 98% concentrated sulfuric acid, hot liquids (water, HCl/NaOH solutions, 30-100 °C), solvent immersion, high temperature, and a long-term period. More importantly, the surface also exhibited robust mechanical durability and could withstand multiple-fold, finger-touch, intensive scratching by a sharp blade, ultrasonication treatment, boiling treatment in water and coffee, repeated peeling by adhesive tape, and even multiple abrasion tests under 500 g of force without losing superamphiphobicity. The as-prepared superamphiphobic surface was also demonstrated to have excellent corrosion resistance. This work provides a simple, cost-effective, and highly efficient method to fabricate a chemically stable and mechanically robust superamphiphobic aluminum surface, which can find important outdoor applications.

Washable and wear-resistant superhydrophobic surfaces with self-cleaning property by chemical etching of fibers and hydrophobization

Superhydrophobic poly(ethylene terephthalate) (PET) textile surfaces with a self-cleaning property were fabricated by treating the microscale fibers with alkali followed by coating with polydimethylsiloxane (PDMS). Scanning electron microscopy analysis showed that alkali treatment etched the PET and resulted in nanoscale pits on the fiber surfaces, making the textiles have hierarchical structures. Coating of PDMS on the etched fibers affected little the roughening structures while lowered the surface energy of the fibers, thus making the textiles show slippery superhydrophobicity with a self-cleaning effect. Wettability tests showed that the superhydrophobic textiles were robust to acid/alkaline etching, UV irradiation, and long-time laundering. Importantly, the textiles maintained superhydrophobicity even when the textiles are ruptured by severe abrasion. Also colorful images could be imparted to the superhydrophobic textiles by a conventional transfer printing without affecting the superhydrophobicity.

Highly efficient and large-scale fabrication of superhydrophobic alumina surface with strong stability based on self-congregated alumina nanowires

In this study, a large-area superhydrophobic alumina surface with a series of superior properties was fabricated via an economical, simple, and highly effective one-step anodization process, and subsequently modified with low-surface-energy film. The effects of the anodization parameters including electrochemical anodization time, current density, and electrolyte temperature on surface morphology and surface wettability were investigated in detail. The hierarchical alumina pyramids-on-pores (HAPOP) rough structure which was produced quickly through the one-step anodization process together with a low-surface-energy film deposition [1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDES) and stearic acid (STA)] confer excellent superhydrophobicity and an extremely low sliding angle. Both the PDES-modified superhydrophobic (PDES-MS) and the STA-modified superhydrophobic (STA-MS) surfaces present fascinating nonwetting and extremely slippery behaviors. The chemical stability and mechanical durability of the PDES-MS and STA-MS surfaces were evaluated and discussed. Compared with the STA-MS surface, the as-prepared PDES-MS surface possesses an amazing chemical stability which not only can repel cool liquids (water, HCl/NaOH solutions, around 25 °C), but also can show excellent resistance to a series of hot liquids (water, HCl/NaOH solutions, 30-100 °C) and hot beverages (coffee, milk, tea, 80 °C). Moreover, the PDES-MS surface also presents excellent stability toward immersion in various organic solvents, high temperature, and long time period. In particular, the PDES-MS surface achieves good mechanical durability which can withstand ultrasonication treatment, finger-touch, multiple fold, peeling by adhesive tape, and even abrasion test treatments without losing superhydrophobicity. The corrosion resistance and durability of the diverse-modified superhydrophobic surfaces were also examined. These fascinating performances makes the present method suitable for large-scale industrial fabrication of chemically stable and mechanically robust superhydrophobic surfaces.