Omniphobic Properties Research Articles

One-step development of photothermal omniphobic membrane for vacuum membrane distillation towards sustainable water desalination using solar energy

Nowadays, development of photothermal omniphobic membranes (POMs) for water desalination using solar energy has gained considerable attention to face water and energy challenges in a sustainable way. Scientists have been developing POM via different techniques based on photothermal component loading and surface energy reduction, all of which suffer from multi-step processes. Obviously, researchers and especially industrial developers aspire to one-step techniques that make the production process highly accelerated and economical. In this study, a one-step technique to develop POMs is demonstrate, using which the omniphobic and photothermal properties are simultaneously imparted to the membrane through being integrated with the membrane fabrication process. The technique works based on elaborate design of membrane surface chemistry and roughness via electrospinning of poly(vinylidene fluoride) (PVDF)/poly(1H,1H,2H,2H-perfluorooctyl acrylate) (PPFOA) blend solution containing carbon black nanoparticles (CB NPs). Optimum concentrations for PPFOA and CB NPs with respect to the PVDF weight were obtained as 60 and 15 wt%, respectively. The developed membrane exhibited permeate flux and salt rejection as high as 2.94 kg/m2·h and > 98 %, respectively, under one sun radiation. Evaporation rate and efficiency of the developed membrane were calculated as 1.49 kg/m2.h and 83.5 %, respectively. The membrane exhibited stable long-term performance for 600 min in contact with the sodium dodecyl sulfate (0.8 mM)-containing NaCl aqueous solution (3.5 wt%). Besides single-step implementation, the introduced technique benefits from endowing the entire membrane structure with omniphobic and photothermal properties not only the membrane surface. This can drastically improve the membrane performance and life time.

Sustainable Manufacturing of Multifunctional Fluorine-Free Superslippery Flexible Surfaces.

Surface contamination and friction result in significant energy losses with widespread environmental impact. In the present work, we developed fluorine-free super-slippery surfaces employing environmentally friendly and simple biofuel-based flame treatment of polydimethylsiloxane (PDMS). Through a unique combination of processing parameters, highly transparent (>90%) and flexible films were engineered with omniphobic, anti-icing, and ultra-low friction properties. The processed films showed an extremely low tilting angle (<5°) and contact angle hysteresis (<4°) against different liquids, even under subzero temperatures. The coefficient of friction (COF) reduced to 0.01 after processing compared to ∼1 for PDMS. Extremely low ice adhesion of <20 kPa and enhanced freezing time ensured anti-icing behavior. The exceptional multidimensional traits were derived from the extremely stable silicone lubricant layer ensured by the hierarchically structured wrinkles. Wind tunnel tests showed that an air drag velocity of less than 0.5 m/s was sufficient to initiate droplet motion, highlighting low interfacial friction that leads to an anti-staining nature. Sustaining the self-cleaning and anti-staining characteristics, the processed surface showed utmost durability under different harsh conditions. The super-slippery surfaces with multifunctional characteristics fabricated through a sustainable route can be effectively used for various engineering and industrial applications.

A rationally designed polymer brush/lubricant coating system for effective static and dynamic marine antifouling

Bioinspired slippery surfaces have garnered significant attention as promising solutions to mitigate biofouling. Unlike traditional lubricant-infused porous surfaces, recent research has focused on the integration of lubricants within polymer brush-grafted surfaces. The combination of polydimethylsiloxane (PDMS) polymer brush and silicone oil has gradually become the most prevalent choice due to their outstanding chemical affinity. However, this conventional coating system also has the potential for improvement to meet the needs of long-lasting and efficient marine antifouling, including i) precisely designing the polymer brush’s chemical structure to match the polarity of a specific lubricant enhances their chemical affinity, and ii) appropriately reduce the coating system’s surface energy to improve the fouling desorption performance. Here, we introduce a systematically engineered polymer brush/lubricant coating system that incorporates fluorinated polysiloxane and perfluoropolyether fluid. This novel coating system exhibits enhanced adhesion strength coupled with reduced surface energy, resulting in superior stability and omniphobic properties. Additionally, it showcases excellent corrosion resistance and significantly deters marine microorganism adhesion, achieving reductions of 98.8 % for P. tricornutum and 99.8 % for Bacillus sp.. Marine field trials, conducted over a 90-day static immersion period, confirm the remarkable antifouling performance, which surpasses most existing slippery coatings. Moreover, under dynamic conditions, organisms adhering for 150 days are readily dislodged by shear force. These findings underscore the pivotal role of systematic design in polymer brush/lubricant coating systems for the advancement of high-performance slippery surfaces tailored for marine antifouling applications.

Robust multifunctional coatings with omniphobic and antistatic properties to repel liquids and solid particles

Multifunctional transparent surfaces, exhibiting omniphobic and antistatic properties to mitigate contamination with both liquids and dust, are reported. The intrinsic electrical conductivity of Laponite (Lap) nanoparticles is combined with the low surface free energy of the perfluoropolyether (PFPE) S10. Lap nanoparticles are functionalized by grafting the PFPE, yielding different S10/Lap ratios. At optimal coating, contact angle values of 114° and 67° are reached for water and hexadecane, respectively, as well as a sheet resistance on the order of 108 Ω/□. Additionally, an excellent ability to repel liquids and reduce the adhesion of dust particles is observed. The mechanical stability of coatings against abrasion is also demonstrated.

Development of a hyperbranched oxazolidinone dynamic omniphobic liquid-like coating with high hardness and flexibility

Dynamic omniphobic liquid-like anti-fouling coatings have a wide range of applications. However, designing dynamic omniphobic liquid coatings that are highly hard, flexible, and low-cost remains a challenge. In this study, low-cost hyperbranched epoxy resin (HEBP), hexamethylene diisocyanate trimer (HDIT), and mono-hydroxyl-terminated poly(dimethysilxane) (HO-PDMS) were used as polymer matrix. Through a copolymerization reaction, a highly cross-linked rigid oxazolidinone structure (OX) and liquid-like molecular coating were obtained. Meanwhile, this unique design endowed the coating with ultra-high hardness (8H), exceptional flexibility, extremely high transparency, and dynamic omniphobic anti-fouling properties. Moreover, the layer can withstand cycles of friction or bending and exhibits excellent chemical barrier properties. Overall, this coating can be easily prepared on a large scale and has broad application prospects in different fields such as solar panels, outdoor public facilities, and flexible display screens.

Transparent and anti-smudge ladder-like polysilsesquioxane coating with high wear resistance and UV aging resistance

With the rapid development of multi-function touch panels, more requirements are raised for touch screens including anti-smudge, anti-fingerprint, and high wear resistance, hardness, and UV resistance. Herein, ladder-like poly(2-(3,4-epoxycyclohexyl)ethyltrimethoxy-co-1H,1H,2H,2H-perfluorodecyltriethoxysilsesquioxane)s (LPEFSQs) were synthesized by the sol-gel reaction of 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane (ECTMS) with 1H,1H,2H,2H-Perfluorodecyltriethoxysilane (PFDTES) to reduce the surface energy of the coating. The incorporation of fluorine chains resulted in an improvement of water contact angle from 77.1° to 115.5°, and oil contact angle from 35.4° to 94.7°, respectively. The omniphobic property rendered the coating excellent anti-smudge and anti-fingerprint properties while maintaining an extraordinary visible light transparency of 90.1 %. A proper PFDTES fraction of 5 % and the curing agent of I-250 are desired for the coating to simultaneously realize excellent pencil hardness of 6H, anti-smudge, and wear resistance performance. The optimized LPEFSQ coating could withstand a steel wool abrasion for 500 cycles. In addition, the developed LPEFSQ coating maintained excellent omniphobicity when subjected to ultraviolet (UV) irradiation for 200 h demonstrating excellent UV resistance. Therefore, this work provides insights into the synthesis of multifunctional coatings integrated with high transparency, wear resistance, and hardness as well as anti-smudge, and anti-fingerprint properties for touch screens.

Endowing Poly(vinylidene fluoride) Membrane Surface with Photothermal and Omniphobic Properties through a Single-step, Electrospinning-based Technique to Enhance Vacuum Membrane Distillation

Nowadays, global shortage of both water and energy makes it vital to develop innovative technologies such as photothermal membrane distillation (PMD) that harvests solar energy for water desalination. Herein, a single-step, facile and scalable technique was employed to create a photothermal omniphobic membrane (POM) for long-term vacuum membrane distillation (VMD). Poly(vinylidene fluoride) (PVDF) electrospun membrane was coated with an omniphobic layer made of poly(1H, 1H, 2H, 2H-perfluorooctyl acrylate) containing varying concentrations of photothermal carbon black nanoparticles (CB NPs) (0, 0.5, 1.0, 2.5 and 5.0 wt%). The prepared POM exhibited strong ability to retain droplets of isopropanol, engine oil and water with contact angles of 113.69°, 127.95° and 150.54°, respectively. The permeate flux through the POM containing 5 wt% CB NPs under 1 sun solar simulator light was 2.5 times higher than that of the pristine PVDF membrane without photothermal activity. Outstanding long-term performance of the prepared POM was verified by conducting VMD to desalinate a saline feed solution containing sodium dodecyl sulfate (SDS) with varying concentrations ranging from 0.2 to 0.8 mM. Overall, it can be concluded that the POM prepared in this work can pave the way for the development of PMD systems with long-term stable performance using solar energy.

Robust omniphobic ceramic hollow fibre membrane with leaf-like copper oxide hierarchical structure by membrane distillation

Omniphobic membranes have recently shown promising performance in water desalination using MD due to their ability to repel all liquid drop types and keep the membrane surface dry. This study successfully modified the surface of robust hydrophilic mullite-stainless steel hollow fibre membranes (M-SS HFMs) to omniphobic properties. The omniphobic layer was achieved through surface grafting with copper oxide (CuO) rough layer by a hydrothermal technique at different hydrothermal reaction times of 1, 2, 3, 4 and 5 h, followed by fluorination step using 1H,1H,2H,2H-perfluorode-cyltriethoxysilane (C8, 97 %). Next, the omniphobic membranes were characterized in terms of membrane morphology, roughness, mechanical strength, pore size/distribution, liquid entry pressure, contact angle and fouling accumulation. The prepared omniphobic M-SS HFMs were also tested through the DCMD system at 80 °C using a feed solution containing 35 g/L of NaCl and 10 mg/L of humic acid as a foulant agent. The results indicated that M-SS HFMs subjected to a 4 h hydrothermal reaction time, resulting in a leaf-like surface structure, exhibited superior characteristics compared to other omniphobic HFMs reported in the literature that used titania (SiO2), zinc oxide (ZnO), and cobalt (Co3O4) as roughing material. These superior features included higher roughness of 0.798 μm, liquid entry pressure of 5.40 bar, and enhanced liquid repellence and contact angles towards DI water of 167°, olive oil of 152°, and ethanol of 145°. Additionally, the M-SS HFMs at 4 h hydrothermal demonstrated remarkable performance in terms of rejection performance (99.99 %) and vapour flux stability of about 29 kg/m2.h in DCMD operations, surpassing the performance of omniphobic HFMs fabricated using mullite-ball clay, mullite-kaolinite, and alumina (Al2O3). Notably, no fouling/wetting on the membrane surface and elements leaching was observed throughout the MD operation. These findings highlight the potential of this omniphobic HFM for seawater desalination using DCMD systems, even in the presence of organic contaminants.

Rational Design and Fabrication Method for Bioinspired Directional Droplet Sliding Surfaces

AbstractA rational design and fabrication method is proposed for fabricating polymeric directional droplet sliding surfaces inspired by butterfly wing microline arrays. The bioinspired structures are fabricated using a simple and well‐designed process that combines the conventional micro‐electromechanical system process with subsequent soft lithography. Three criteria to avoid fabrication errors during silicon mold production are suggested. The fabricated silicon master serves as a reliable and robust semi‐permanent mold for polymeric replication, resulting in bioinspired surfaces with high fidelity. The successfully fabricated bioinspired fabricated structure surface has a re‐entrant shape line structure and exhibits directional omniphobic properties while maintaining transparency. The fabricated surface is found to transport droplets in the direction where microlines are formed without wetting by various droplets, including water and oil. The results show that this surface can be applied to various fields. This study has implications for the development of artificial surfaces inspired by nature for various fields, including microfluidics, biotechnology, and energy‐harvesting devices.

Dependence of Slippery and Elastic Properties of Thin Polymer Films on the Grafted Flexible Sidechain Amount

In modern life, people face a wide number of sticky problems when adhesion is highly undesirable: water and dirt stick to clothes, useful materials stick to the walls of their containers and cannot be fully used, water sticking and freezing on airplane wings affects handling and can be dangerous, biological liquids can stick and form clots inside medical devices threatening patients' lives, etc. Slippery liquid-infused porous surfaces (SLIPSs) with pressure stable omniphobicity could help to solve these issues. Lubricant depletion from porous surface and subsequent degradation of omniphobic properties is the major problem for SLIPS. It could be resolved by attaching flexible, liquid-like sidechains to the polymer matrix. Understanding the relationship between the structure of such polymer films and wetting effects is therefore of great importance. The present work is devoted to the study of droplet pinning on crosslinked polydimethylsiloxane (PDMS) polymer films with varied amounts of attached flexible PDMS sidechains and clarification of the relationship between slippery and viscoelastic properties of the films. An one-stage approach to the synthesis of such slippery coatings on smooth and porous substrates in "eco-friendly" pressurized CO2 solutions is proposed. Pinning force and Young's modulus (E) of the films on silicon substrates with variation of the grafted sidechains amount (x) are measured. The non-monotonic dependence of the pinning force on the amount of sidechains is obtained: the pinning force decreases at small x values (region I) and starts to increase at higher x (region II). The effects of the grafted sidechains amount, as well as matrix softening, are discussed for each case. It is demonstrated that the proposed method of film synthesis allows one to obtain thin, uniform coatings on fabrics without gluing the fibers. Such coatings with an optimal amount of PDMS sidechains demonstrate decreased sliding angles for droplets of water and aqueous alcohol solutions, as compared to PDMS coatings without grafted sidechains. The proposed technique may be of interest for deposition of coatings on porous surfaces having a complex morphology, such as textiles, aerogels, porous electrodes, etc.

Fabrication of Omniphobic‐Omniphilic Micropatterns using GPOSS‐PDMS Coating

AbstractSurfaces with special wettability properties, such as omniphobicity or omniphilicity, are essential for functional devices that use both aqueous and organic media. Micropatterning of omniphobic and omniphilic properties can provide a wide range of applications, including miniaturized experiments using both aqueous and organic media. Herein, an approach for creating omniphobic‐omniphilic micropatterns based on selective photoacid polymerization of octa(3‐glycidyloxypropyl) polyhedral oligomeric silsesquioxane modified with mono‐aminopropyl‐terminated polydimethylsiloxane is reported. The composition of the polymeric coatings using infrared spectroscopy; patterning accuracy using atomic force microscopy and scanning electron microscopy; wettability characteristics of the omniphobic, and omniphilic surfaces using contact angle measurements are studied. The proposed approach allows for single‐step micropatterning (sub‐10 µm) or macropatterning (3 mm). Liquids with surface tensions &gt;22.8 mN m−1 can be confined to the omniphilic areas by the omniphobic borders. C2C12 cells are successfully cultivated in omniphilic areas, demonstrating their cell compatibility. The cells adhere to and grow on the entire surface of the pattern, without any signs of cytotoxicity. However, the strongest adhesion is observed in the omniphilic areas, making it possible to create cell micropatterns in a single step. The proposed method for the fabrication of omniphobic‐omniphilic transparent, mechanically robust, biocompatible patterns can find applications in microfluidics, biotechnology or miniaturized biological screening experiments.

Highly-transparent fluorinated epoxy coating prepared via ring-opening of thiolactone and thiol-click reactions for robust omniphobicity

Transparent omniphobic coatings have attracted extensive research over the past decade to meet growing application demands. Polydimethylsiloxane (PDMS)-based anti-fouling coatings have been widely reported to contribute a liquid-like surface for liquid repellency. The bulky PDMS chains usually make the surface greasy and energy-consuming. Fluorinated epoxy is expected to overcome the above drawbacks and contribute to excellent mechanical robustness. However, the reported fluorinated epoxy coatings are unsatisfactory due to severe phase separation, excessive fluorine content, poor self-healing and weatherability. In this work, a thiolactone-terminated fluorinated prepolymer (TTFP) was prepared through thiol-click chemistry. The thiolactone structure limited the phase separation and reacted efficiently with epoxy resin in a thiol-click manner after ring-opening. The flexible TTFP molecules had a strong surface migration ability, allowing the product coating to be liquid repellent with a low fluorine content and self-healed after damage. Therefore, a low-cost, eco-friendly, anti-ultraviolet, self-healed, highly transparent, mechanically robust and chemically resistant fluorinated epoxy coating was proposed. In addition to the excellent repellency to ink traces, fingerprints and thick paint, the coating with 5H pencil hardness could maintain omniphobic properties after 100 h of intensive UV irradiation or 12 h of alkali corrosion. Benefiting from the strong surface migration ability of flexible fluoroalkyl chains, the coating could recover its omniphobicity within 30 min of heating. The characterization results show the excellent comprehensive properties of the coating and its great potential for application in various scenarios.

Transparent and anti-fouling perfluoropolyether coating with superior wear resistance

Perfluoropolyether (PFPE) siloxanes can be used as anti-fouling coating materials due to their simple large-scale preparation, transparency and omniphobic properties, but their wear resistance needs to be enhanced dramatically. Herein, we designed and synthesized a series of high-purity PFPE-siloxanes with different average molecular weights of PFPE chains and different numbers of trimethoxysilane groups. Then, these PFPE-siloxanes were coated on glass plates in a one-step dip coating process. The influence of the average molecular weight of PFPE chains and the number of trimethoxysilanes on the wear resistance of these PFPE films were investigated by the measurement of static contact angle and sliding angle of water, morphology and relative elemental content on the surface after different times of reciprocating friction. The film prepared from the PFPE-siloxanes combining a longer PFPE chain with more trimethoxysilane terminal groups possessed not only good transparency and excellent antifouling properties, but also presented superior wear resistance and anti-fingerprint properties. The surface wetting characteristic and morphology barely changed after 9000 times of friction with hard rubber under a 255 kPa pressure. The PFPE-siloxanes with excellent antifouling property and transparency make them as preferred candidates for engineering application fields.

Structural design of the electrospun nanofibrous membrane for membrane distillation application: a review.

Although membrane distillation (MD) is a promising technology for water desalination and industrial wastewater treatment, the MD process is not widely applied in the global water industry due to the lack of a suitable membrane for the MD process. The design and appropriate manufacture are the most important factors for MD membrane optimization. The well-designed porous structure, superhydrophobic surface, and pore-wetting prevention of the membrane are vital properties of the MD membrane. Nowadays, electrospinning that is capable of manufacturing membranes with superhydrophobic or omni phobic properties is considered a promising technology. Electrospun nanofibrous membranes (ENMs) possess the characteristics of cylindrical morphology, re-entrant structure, and easy-shaping for a specific purpose, benefiting the membrane design and modification. Based on that, this review investigates the current state and future progress of the superhydrophobic, multi-layer, and omniphobic ENMs manufactured with various structural designs for seawater desalination and wastewater purification. We expect that this paper will provide some recommendations and guidance for further fabrication research and the configuration design of ENMs in the MD process for seawater desalination and wastewater purification.

Contamination and carryover free handling of complex fluids using lubricant-infused pipette tips

Cross-contamination of biological samples during handling and preparation, is a major issue in laboratory setups, leading to false-positives or false-negatives. Sample carryover residue in pipette tips contributes greatly to this issue. Most pipette tips on the market are manufactured with hydrophobic polymers that are able to repel high surface tension liquids, yet they lack in performance when low surface tension liquids and viscous fluids are involved. Moreover, hydrophobicity of pipette tips can result in hydrophobic adsorption of biomolecules, causing inaccuracies and loss in precision during pipetting. Here we propose the use of lubricant-infused surface (LIS) technology to achieve omniphobic properties in pipette tips. Using a versatile and simple design, the inner lumen of commercially available pipette tips was coated with a fluorosilane (FS) layer using chemical vapor deposition (CVD). The presence of FS groups on the tips is confirmed by x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) tests. After lubrication of the tips through a fluorinated lubricant, the omniphobicity and repellent behaviour of the tips drastically enhanced which are revealed via static and hysteresis contact angle measurements. The repellency of the lubricant-infused pipette tips against physical adsorption is investigated through pipetting a food coloring dye as well as human blood samples and are compared to the untreated tips. The results show significantly less amount carryover residue when the lubricant-infused tips are utilized compared to commercially available ones. We also demonstrate the lubricant-infused tips reduce bacteria contamination of the inner lumen by 3 to 6-log (over 99%, depending on the tip size) after pipetting up and down the bacteria solution.

Fluorinated phosphonium salts and ionic liquids prepared via thiol-ene click chemistry: a physical and thermal property study

• Synthesis of 18 fluorinated phosphonium salts using thiol-ene click chemistry. • 14 of the salts are ionic liquids (ILs), 5 are liquids at room-temperature (RTILs) • 2 ILs show supercooling behavior, eventually solidifying over time. • Several ILs show interesting thermal behavior, possibly due to domain segregation. • X-ray crystal structure shows segregation between fluorous and non-fluorous domains. Using thiol-ene “click” chemistry, a fluorinated thiol was systematically investigated against a series of allyl-quaternized phosphonium substrates in the pursuit of cation-fluorinated ionic liquids with omniphobic (hydrophobic and oleophobic) properties for aerospace applications. A total of 18 new cation-fluorinated salts were prepared containing either the bromide (Br – ), bis(trifluoromethanesulfonyl)imide (Tf 2 N – ), hexafluorophosphate (PF 6 – ), or tetrafluoroborate (BF 4 – ) anions. Melting point analysis by visual inspection and differential scanning calorimetry (DSC) revealed that 14 of the salts are ionic liquids with melting points below 100 °C. Five are liquids at room temperature, although two exhibit supercooling behavior and eventually solidify over time. In addition to the standard characterization techniques used to verify compound identity, thermal behavior was studied via DSC and thermogravimetric analysis (TGA). Single-crystal X-ray diffraction was performed on the ionic liquid, triphenyl[3-(1 H ,1 H ,2 H ,2 H -perfluorodecylthio)propyl]phosphonium bis(trifluoromethanesulfonyl)imide. The crystal structure shows fluorous and non-fluorous domains, complementing the thermal behavior observed via DSC. Density, viscosity, surface tension, solubility, and water content were measured in an effort to explore the materials’ physical properties for future applications.

Crosslinking inert liquidlike polydimethylsiloxane brushes using bis-diazirine chemical insertion for enhanced mechanical durability

Inert polymer brushes offer excellent omniphobic and antifouling properties but enhancing their durability remains a challenge, since their chemical inertness also means they lack the functionality necessary for traditional crosslinking reactions. We report the crosslinking of nanoscale polydimethylsiloxane (PDMS) brushes on surfaces through a chemically non-destructive C–H insertion. bis-Diazirine crosslinkers are employed to covalently link methyl groups (i.e., insertion into Si–C–H bonds) along neighboring PDMS chains upon thermal activation. The successful crosslinking of PDMS brushes is evidenced directly by X-ray photoelectron spectroscopy analysis and indirectly through mechanical durability characterization using Martindale abrasion. The apparent contact angles and low contact angle hysteresis of crosslinked PDMS brushes are well-maintained post abrasion, indicating enhanced mechanical durability as compared to uncrosslinked brushes. The longevity of the liquidlike character of crosslinked PDMS brushes is also improved following mechanical wear, with a shear ice adhesion strength half that of uncrosslinked brush surfaces. The crosslinked surfaces are also resistant to acid corrosion, heating, sonication, and tape peeling, indicating that the physicochemical stability of PDMS brushes is not degraded upon crosslinking. Finally, crosslinked brushes are additionally deposited on polycarbonate substrates, and the optical transparency, enhanced durability, and droplet shedding capability of the coated substrates are demonstrated. Overall, this study provides a new pathway for the design of durable inert nanoscale coatings that maintain their attractive surface properties after mechanical wear.

Robust fabrication of double-ring mushroom structure for reliable omniphobic surfaces

This paper presents a novel fabrication method for an unusual cylindrical double-ring mushroom structure (DMS). By using a conventional lithography process, a stable microstructure with omniphobic properties was constructed without additional chemical surface treatment with superior structural characteristics. The novelty of this DMS fabrication is demonstrated through footing effect errors that could occur during the silicon master fabrication process and demolding errors that could occur during the polymer replica process. The excellent omniphobic property of DMS is also demonstrated through a wettability test with comparisons of structures of similar dimension, and it exhibited strong resistance to contamination through comparative experiments of transmittance. As a result, thanks to low-cost fabrication method which does not require additional chemical treatment, our outstanding results with polymeric DMS surfaces are expected to affect various application fields.

A spontaneous one-step fabrication of slippery gel coatings

Lubricant infused surfaces (LIS) have omniphobic repulsion towards most liquids and have applications in various fields. The initial subtractive fabrication methods were multiphase, complex, and substrate limited, requiring specific surface topologies functionalised with fluorosilanes before being infused with low surface tension lubricants. Numerous additive approaches have been developed to overcome these limitations, including chemical, nanoparticle, and polymeric layers. While effective, these coatings still require complex or multi-step syntheses with expensive compounds and substrate limiting fabrication conditions. This paper will present a single-step fabrication methodology for an omniphobic slippery gel coating, predicated on spontaneous urea cross-linking between branched polyethyleneimine and isocyanate bi-terminated perfluoropolyether, with a hydroxy bi-terminated PFPE as both solvent and lubricant. The resulting coatings showed the presence of fluorine and carbon chemistries, and the formation and size of raised island topologies (from the nano – micro range) correlating to the molar ratio of the coating solutions. Extensive examination of the contact and sliding angles of water, canola oil, and n-hexane showed that coatings retained omniphobic properties after numerous lubricant layer removals via pure ethanol. The rapid and facile methodology used to produce the fluorogel coatings allows for an easy transition into larger-scale industrial applications.

Bioinspired Omniphobic Microchamber Structure

AbstractIn this study, a novel cylindrical, mushroom‐shaped architecture array is proposed to achieve containable microchamber structures with stable omniphobic properties. By implementing a simple yet robust lithography method, a unique geometry of a double‐tip shape with high structural fidelity is fabricated. Such cylindrical re‐entrant structures are found to have omniphobic properties without surface chemical treatments. A microchamber morphology based on the formation of a Norland optical adhesive polymer roof on the surfaces of the donut‐shaped tip structures with micro‐dewetting phenomena is also demonstrated. Finally, SiO2 nanoparticles with an average size of 1.5 µm are successfully stored in the microchamber and protected with the polymer roof. This is expected to provide innovative inspiration for various application areas.