Transparent and Robust Amphiphobic Surfaces Exploiting Nanohierarchical Surface-grown Metal-Organic Frameworks.

Highly amphiphobic (repelling both water and low surface tension liquids) and optically transparent surface treatments have widespread demand. By combining a rational growth of metal-organic frameworks (MOFs) with functionalization by environmentally safe, flexible alkyl groups, here we present surfaces with nanohierarchical morphology, comprising two widely differing nanoscale features. These nanohierarchical MOF films show excellent amphiphobicity. We further present three key features. First, we demonstrate the need to use flexible alkyl chains to achieve low drop sliding angles and self-cleaning. Second, our thin (∼200 nm) MOF films display excellent optical transparency and robustness. Third, the nanohierarchical morphology enables a unique combination of additional desirable properties, e.g., resistance to high-speed liquid impact (up to ∼35 m/s, Weber number >4 × 104), thermal stability up to 200 °C, scratch resistance, low ice adhesion for >10 icing/deicing cycles, stability in harsh acidic and basic environments, and capability to remove carcinogenic pollutants from water.

Designing a Network of Crystalline Polymers for a Scalable, Nonfluorinated, Healable and Amphiphobic Solid Slippery Interface.

The fluorinated-liquid infused amphiphobic slippery interfaces exhibiting superior sliding of the beaded oil/water droplets, often suffer from durability and contamination issues. Here, the ability of 1) hexagonal packing of hydrocarbon sides in a selected "comb-like" polymer and 2) its reversible phase transition at 51 °C was rationally exploited to achieve temperature-assisted rapid (<1 minute) and repetitive (50 times) self-healable amphiphobic solid-slippery coating on both planar and geometrically-complex substrates. The selected "comb-like" polymer was strategically infused in a porous, hydrophilic and thick (≈4.8 µm) polymeric coating. The resultant solid and smooth interface exhibited sliding of beaded droplets of various liquids, including droplets of water, polar (ethanol, 1-propanol, 1-hexanol, DMSO, DMF), and non-polar (decane, dodecane, diiodomethane) organic solvents, edible (vegetable oil), motor, engine (petrol, diesel, kerosene) and crude oils.

Nanoparticle-free and self-healing amphiphobic membrane for anti-surfactant-wetting membrane distillation.

In membrane distillation (MD), complicated feed water with amphiphilic contaminants induces fouling/wetting of the MD membrane and can even lead to process failure. This study reports a facile approach to fabricate robust and self-healing hybrid amphiphobic membranes for anti-surfactant-wetting MD based on the ultra-low surface energy of fluorinated polyhedral oligomeric silsesquioxanes (F-POSS) and its thermal induced motivation and rotation. The thermal treatment makes the membranes achieving amphiphobicity at a very low cost of F-POSS (13.04 wt.%), which is about 1/3 of without thermal treatment. The prepared membrane exhibits excellent amphiphobicity, i.e. ethanol contact angle of 120.3°, without using environmentally toxic fluorinated nanoparticles. Robust MD performance was observed for the amphiphobic membrane in concentrated sodium dodecyl sulfate (SDS) feed solutions. Furthermore, the fabricated membrane exhibited stable amphiphobicity even in extreme environments, including strong acid or alkaline solutions. In the event of a damaged or abraded membrane surface where the F-POSS can be removed, the amphiphobic membrane exhibits self-healing ability with additional thermal treatment. This simple approach without the use of nanoparticles provides an environmentally friendly way for fabrication of amphiphobic membranes for anti-surfactant-wetting membrane distillation.

A review of membrane development in membrane distillation for emulsified industrial or shale gas wastewater treatments with feed containing hybrid impurities.

Investigations on membrane materials for membrane distillation (MD) and its applications have been ongoing since the 1990s. However, a lack of materials that produce robustly stable and up-to-the-mark membranes for MD for different industrial applications remains an ongoing problem. This paper provides an overview of materials developed for MD applications. Although key aspects of published articles reviewed in this paper pertain to MD membranes synthesized for desalination, future MD can also be applied to organic wastewater containing surfactants with inorganic compounds, either with the help of hybrid treatment processes or with customized membrane materials. Many industrial discharges produce effluents at a very high temperature, which is an available driving force for MD. However, there remains a lack of cost-effective membrane materials. Amphiphobic and omniphobic membranes have recently been developed for treating emulsified and shale gas produced water, but the problem of organic fouling and pore wetting remains a major challenge, especially when NaCl and other inorganic impurities are present, which further deteriorate separation performance. Therefore, further advancements in materials are required for the treatment of emulsified industrial wastewater containing surfactants, salts, and for oil or shale gas wastewater for its commercialized reuse. Integrated MD systems, however, may represent a major change in shale gas wastewater and emulsified wastewater that are difficult to treat.

Super-amphiphobic arabic gum-based coatings on textile for on-demand oily and dye wastewater treatment.

Different membrane materials have broadly been constructed for oil-containing water separation, but most of preparation routes involve corrosive or toxic chemicals and especially many materials have only single superwetting property. Herein, a novel and eco-friendly cellulose-based textile membrane is developed by incorporating the composite coating consisting of arabic gum (AG), attapulgite (APT), and iron (Fe) onto cellulose textiles. The functionalized textile is superoleophobic underwater and superhydrophobic underoil. As a result, the textile prewetted with water or oil can be employed to separate light oil layer/water and heavy oil layer/water mixtures, respectively, and the separation efficiency to the two types of mixtures is larger than 98.3 %. Results also reveal that the decorated textile possesses superior stability and recyclability in purifying oily wastewater. More importantly, such coated textile is capable of filtrating water-soluble contaminants (dyes) from polluted water. Due to the versatility and environmental compatibility of product as well as the accessibility as agricultural and forestry product as raw materials, the advanced textiles may offer effective solutions to oily wastewater purification and water-soluble contaminant removal.

Precision Covalent Organic Frameworks for Surface Nucleation Control.

Unwanted accumulation of ice and lime scale crystals on surfaces is a long-standing challenge with major economic and sustainability implications. Passive inhibition of icing and scaling by liquid-repellent surfaces are often inadequate, susceptible to surface failure under harsh conditions, and unsuitable for long-term/real-life usages. Such surfaces often require a multiplicity of additional features such as optical transparency, robust impact resistance, and ability to prevent contamination from low surface energy liquids. Unfortunately, most promising advances have relied on using perfluoro compounds, which are bio-persistent and/or highly toxic. Here it is shown that organic, reticular mesoporous structures, covalent organic frameworks (COFs), may offer a solution. By exploiting simple and scalable synthesis of defect-free COFs and rational post-synthetic functionalization, nanocoatings with precision nanoporosity (morphology) are prepared that can inhibit nucleation at the molecular level without compromising the related contamination prevention and robustness. The results offer a simple strategy to exploit the nanoconfinement effect, which remarkably delays the nucleation of ice and scale formation on surfaces. Ice nucleation is suppressed down to -28 °C, scale formation is avoided for >2 weeks in supersaturated conditions, and jets of organic solvents impacting at Weber numbers >105 are resisted with surfaces that also offer optical transparency (>92%).

Area-Selective Atomic Layer Deposition on Metal/Dielectric Patterns: Amphiphobic Coating, Vaporizable Inhibitors, and Regenerative Processing.

Area-selective atomic layer deposition (AS-ALD) has drawn significant attention in the past decade because of the potential applications in bottom-up processing, which enables fabricating nanostructures at the atomic level without multiple patterning and lithographic processing that could easily cause alignment issues. Although AS-ALD has been demonstrated using various self-assembled monolayers (SAMs), it is still challenging to develop wet SAM deposition for AS-ALD that is suitable for industrial and semiconductor processes. In this work, we demonstrate highly effective AS-ALD of Al2O3 on Co/SiO2 patterned wafers using fluorinated thiol in both solution and vapor phase. Compared with conventional SAMs using alky-thiols, the fluorinated-thiol SAMs demonstrate greater blocking ability against ALD precursors owing to excellent hydrophobicity. Furthermore, much shorter deposition times can be achieved in vaporizable fluorinated thiol molecules, improving processing throughput and productivity. Most importantly, the SAM regeneration and redosing processes can further enhance the selectivity of AS-ALD, opening a promising avenue to realize the bottom-up approach in practical semiconductor applications.

Development of a Carbon Nanotube-Enhanced FAS Bilayer Amphiphobic Coating for Biological Fluids.

This study reports the development of a novel amphiphobic coating. The coating is a bilayer arrangement, where carbon nanotubes (CNTs) form the underlayer and fluorinated alkyl-silane (FAS) forms the overlayer, resulting in the development of highly amphiphobic coatings suitable for a wide range of substrates. The effectiveness of these coatings is demonstrated through enhanced contact angles for water and artificial blood plasma fluid on glass, stainless steel, and porous PTFE. The coatings were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), atomic force microscopy (AFM), and contact angle (CA) measurements. The water contact angles achieved with the bilayer coating were 106 ± 2°, 116 ± 2°, and 141 ± 2° for glass, stainless steel, and PTFE, respectively, confirming the hydrophobic nature of the coating. Additionally, the coating displayed high repellency for blood plasma, exhibiting contact angles of 102 ± 2°, 112 ± 2°, and 134 ± 2° on coated glass, stainless steel, and PTFE surfaces, respectively. The presence of the CNT underlayer improved plasma contact angles by 29%, 21.7%, and 16.5% for the respective surfaces. The presence of the CNT layer improved surface roughness significantly, and the average roughness of the bilayer coating on glass, stainless steel, and PTFE was measured to be 488 nm, 301 nm, and 274 nm, respectively. Mechanistically, the CNT underlayer contributed to the surface roughness, while the FAS layer provided high amphiphobicity. The maximum effect was observed on modified glass, followed by stainless steel and PTFE surfaces. These findings highlight the promising potential of this coating method across diverse applications, particularly in the biomedical industry, where it can help mitigate complications associated with device-fluid interactions.

Environmentally Friendly Polyamide Nanofiber Membranes with Interconnective Amphiphobic Channels for Seawater Desalination.

Seawater desalination is a promising and sustainable solution to alleviate freshwater scarcity; however, most existing desalination membranes suffer from poor channel interconnectivity and toxic solvent processing and encounter a tradeoff dilemma of salt rejection and water flux. Herein, we report a unique and facile one-step green solvent/nonsolvent spinning methodology to assemble environmentally friendly polyamide nanofiber membranes with a precisely designed interconnective/stable channel structure and surface anti-wettability for seawater desalination. Direct electrospinning without any post-treatments via in situ introduction of fluorinated chemicals enables highly interconnective amphiphobic channels within polyamide membranes, and the incorporation of nonsolvent (diacetone alcohol) into polyamide/solvent (ethanol) spinning solutions endows the green alcohol-based polyamide membranes with a stable bonding structure and small pore size. The resultant green solvent/nonsolvent-spun polyamide nanofiber membranes show impressive liquid entry pressure (120.5 kPa) and vapor permeation (12.5 kg m-2 d-1), achieving robust seawater desalination performance with a salt rejection of 99.97% and permeate flux of 47.4 kg m-2 h-1. The facile one-step solvent/nonsolvent spinning strategy, highly interconnective amphiphobic channels, and green solvent-based environmental friendliness in this work can open opportunities for future polyamide membranes for practical applications in water purification.

Transparent and Flexible Amphiphobic Coatings with Excellent Fold Resistance via Solvent-Free Coating and Photocuring of Fluorinated Liquid Nitrile-Butadiene Rubber.

Amphiphobic surfaces have been developed for various applications. However, the harsh construction conditions and multistep processes limit their practical application. Especially for those with a particular surface roughness and morphology, the amphiphobic property might provide a slight deformation. Here, a facile large-area construction of transparent and flexible amphiphobic coatings with excellent fold resistance has been established by simple casting of the fluorinated liquid nitrile-butadiene rubber (F-LNBR) followed by solvent-free photocuring. It was found that the fluorocarbon groups could concentrate onto the coating surface during the UV-induced photocuring. With a certain coating amount, a stable oleophobic coating was achieved with static contact angles of about 95° and 111° for nonpolar oil (n-hexadecane) and polar oil (diiodomethane). Most importantly, the static contact angles of water and diiodomethane of the amphiphobic coatings on the iron sheet increased after bending and remained around 131° and 120° after being completely folded in half for 100 cycles because the inner fluorocarbon groups could be squeezed out from the flexible cross-linked rubber matrix as a reservoir. Such features indicated the promising self-cleaning and surface protection of the proposed transparent and flexible amphiphobic coatings for deformable substrates.

High transmittance and highly amphiphobic coatings for environmental protection of solar panels.

In this work the authors review the recent literature related to new solutions to prepare coatings with amphiphobic properties in order to provide self-maintaining systems able to limit the human intervention especially in large plants or harsh environments or, generally speaking, to keep the original functionalities of a solar module. Amphiphobic coatings match the requirements preventing both water and oil based pollutants from dust accumulation to natural and urban aerosols, from agriculture dispersions to bird droppings. The increasing need of renewable energy requires this step to be seriously faced with the aim to increase the yield and decrease the modules degradation. Still many issues have to be overcome and here we focus on surface aspects of aging and possible maintenance of the optical features of a solar panel.

Static Wettability of Differently Mechanically Treated and Amphiphobic-Coated Aluminium Surfaces.

Wettability, roughness and surface treatment methods are essential for the majority of practical applications, where liquid-solid surface interactions take place. The present study experimentally investigated the influence of different mechanical surface treatment methods on the static wettability of uncoated and amphiphobic-coated aluminium alloy (AlMg3) samples, specially focusing on the interaction between surface finishing and coating. Five different surfaces were prepared: as-received substrate, polished, sandpapered, fleece-abraded and sandblasted. After characterisation, the samples were spray-coated using an amphiphobic coating. The characterisation of the uncoated and coated samples involved measurements of the roughness parameters and the apparent contact angles of demineralized water and rapeseed oil. The coating was initially characterised regarding its adhesion to the sample and elevated temperature stability. The applied surface treatments resulted in the scattered sample roughness in the range of Sa = 0.3-15.8 µm, water contact angles of θ a p , w = 78°-106° and extremely low oil contact angles. Coating the samples more than doubled the surface roughness to Sa = 13.3-29 µm, whereas the initial surface treatment properties (structure, anisotropy, etc.) were entirely repressed by the coating properties. Coating led the water contact angles to increase to θ a p , w _ c o a t e d = 162°-173° and even more pronounced oil contact angles to increase to θ a p , o _ c o a t e d = 139°-150°, classifying the surfaces as superhydrophobic and oleophobic.

Robust Photothermal Coating Strategy for Efficient Ice Removal.

Preventing ice formation and ice swift removal from the solid surface are essential in numerous application fields. Superhydrophobic coating is an effective way to delay the icing phenomenon. However, the superhydrophobic coating was wetted easily after icing-deicing cycles that led to the failure of anti-icing. In this study, a robust, amphiphobic coating consisted of fluorinated multiwalled carbon nanotubes (FMWCNTs) and commercial polyurethane was constructed by a simply spray process. Because of the addition of FMWCNTs, the coating demonstrated a good amphiphobic feature and highly efficient photothermal conversion, which endowed the coating surface with excellent deicing and defrosting characteristics under sunlight irradiation. In addition, self-cleaning and self-healing properties of the coating under sunlight ensured its efficient photothermal conversion and long service life. To further improve the photothermal deicing effect, a coating system containing a photothermal layer (P), thermal-conductive layer (C), and thermal-protective layer (P) was constructed. The heat generating from the photothermal layer can transfer the whole coating surface by the conductive layer, but with limited transmission to substrate materials by a thermal-protective layer. The coating system can still deice and defrost rapidly on the whole surface and only a small portion of photothermal coating was irradiated under extremely low temperature. The outdoor experiment has confirmed that the coating melted and removed snow rapidly in a winter environment. The multifunctional photothermal deicing coating may have a wide application in outdoor surrounding.

Robust Amphiphobic Few-Layer Black Phosphorus Nanosheet with Improved Stability.

Few-layer black phosphorus (FL-BP) has been intensively studied due to its attractive properties and great potential in electronic and optoelectronic applications. However, the intrinsic instability of FL-BP greatly limits its practical application. In this study, the amphiphobic FL-BP is achieved by functionalization of 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFDTS) on the surface of FL-BP. The obtained PFDTS coated FL-BP (FL-BP/PFDTS) demonstrates enhanced stability, which is not observed during significant degradation for 2 months in high moisture content environment (95% humidity). Particularly, attributing to the surface amphiphobicity, FL-BP/PFDTS exhibits strong surface water repellency in the presence of oleic acid (as the contaminant), while other passivation coating layers (such as hydrophilic or hydrophobic coating) become hydrophilicity under such conditions. Owing to this advantage, the obtained FL-BP/PFDTS demonstrates enhanced stability in high moisture content environment for 2 months, even though the surface is contaminated by oil liquid or other organic solvents (such as oleic acid, CH2Cl2, and N-methyl-2-pyrrolidone). The passivation of FL-BP by amphiphobic coating provides an effective approach for FL-BP stabilization toward future applications.

One-Step Synthesis of Statically Amphiphilic/Dynamically Amphiphobic Fluoride-Free Transparent Coatings.

Although amphiphobic materials have attracted tremendous attention recently owing to their many important applications, there remain some critical challenges such as complex or expensive fabrications, poor long-term stability, nontransparency, etc. Herein, we develop a novel kind of amphiphobic materials-statically amphiphilic but dynamically amphiphobic fluoride-free transparent coating-through one-step reaction. The obtained transparent coating can be readily applied to different kinds of substrates including flat surfaces, curved surfaces, or inner walls of some tubes and bottles, and demonstrate excellent repellency against various high/low-surface-tension liquids and outstanding stability against external damages.

Fabrication of ordered honeycomb amphiphobic films with extremely low fluorine content.

A series of poly(methyl methacrylate)-block-poly(perfluoroalkyl ethyl acrylate) (PMMA-b-PFAEA) with various fluorine content were employed to fabricate honeycomb ordered films via breath figure strategy. The influences of temperature, concentration, relative humidity, fluorine content on the morphology of porous films were investigated. Wetting behavior including hydrophobic property and wetting state of the films was studied. High surface roughness from the porous structure and low surface free energy from the increasing PFAEA fraction led to the enhancement of hydrophobicity. Additionally, fabrication of porous films by the mixture of PMMA and PMMA-b-PFAEA was investigated. Ordered porous film with excellent hydrophobicity and oleophobicity was obtained with only 7 wt% of PMMA-b-PFAEA by simultaneous processes of breath figure mechanism and phase separation. This work facilitates our further comprehension of the mechanism of breath figure and contributes to the fabrication of porous film from fluorinated copolymers. Meanwhile, it opens a new route to prepare films possessing excellent hydrophobicity and oleophobicity with extremely low fluorine content.

Amphiphobic Polytetrafluoroethylene Membranes for Efficient Organic Aerosol Removal.

Polytetrafluoroethylene (PTFE) membrane is an extensively used air filter, but its oleophilicity leads to severe fouling of the membrane surface due to organic aerosol deposition. Herein, we report the fabrication of a new amphiphobic 1H,1H,2H,2H-perfluorodecyl acrylate (PFDAE)-grafted ZnO@PTFE membrane with enhanced antifouling functionality and high removal efficiency. We use atomic-layer deposition (ALD) to uniformly coat a layer of nanosized ZnO particles onto porous PTFE matrix to increase surface area and then subsequently graft PFDAE with plasma. Consequently, the membrane surface showed both superhydrophobicity and oleophobicity with a water contact angle (WCA) and an oil contact angle (OCA) of 150° and 125°, respectively. The membrane air permeation rate of 513 (m(3) m(-2) h(-1) kPa(-1)) was lower than the pristine membrane rate of 550 (m(3) m(-2) h(-1) kPa(-1)), which indicates the surface modification slightly decreased the membrane air permeation. Significantly, the filtration resistance of this amphiphobic membrane to the oil aerosol system was much lower than the initial one. Moreover, the filter exhibited exceptional organic aerosol removal efficiencies that were greater than 99.5%. These results make the amphiphobic PTFE membranes very promising for organic aerosol-laden air-filtration applications.

Phospholipid-stabilized mesoporous carbon nanospheres as versatile carriers for systemic delivery of amphiphobic SNX-2112 (a Hsp90 inhibitor) with enhanced antitumor effect.

Systemic delivery of amphiphobic drugs (insoluble in both water and oil) represents a formidable challenge in drug delivery. This work aimed to engineer a functional mesoporous carbon material to efficiently load SNX-2112, an amphiphobic anticancer agent, and to evaluate its performance in tumor-targeting delivery. Hydrothermal reaction combined with high-temperature activation was used to fabricate glucose-based mesoporous carbon nanospheres (MCNs). SNX-2112-loaded MCNs stabilized by phospholipid (SN-PMCNs) were prepared by the absorption/solvent diffusion/high-pressure homogenization method. The obtained SN-PMCNs were 180nm around in particle size, showing a high drug load (42.7%) and acceptable physical stability. SN-PMCNs demonstrated an enhanced in vitro antitumor effect and increased uptake into cancer cells in comparison with the formulation of SNX-2112 solution (SN-Sol). The in vivo antitumor effect and biodistribution in 4T1 xenograft tumor mice, a breast cancer model, were also significantly improved through SN-PMCNs. It was shown that specific clathrin-dependent and nonspecific caveolae-dependent endocytosis were involved in the cellular trafficking of SN-PMCNs. Glucose transporter-mediated transport, prolonged body residence time and improved biodistribution via EPR effect were the main mechanisms of enhanced antitumor effect. SN-PMCNs have presented excellent tumor targeting properties and should be a promising carrier to address the systemic delivery of SNX-2112.