Fluorinated Silica Nanoparticles Research Articles

Preparation of Pressure-Resistant and Mechanically Durable Superhydrophobic Coatings via Non-Solvent Induced Phase Separation for Anti-Icing.

Inspired by the lotus leaf effect, superhydrophobic coatings have significant potential in various fields, However, their poor pressure resistance, weak mechanical durability, and complex preparation processes severely limit practical applications. Here, a method for preparing pressure-resistant and durable superhydrophobic coatings by simply spray-coating a phase separation suspension containing fluorinated silica nanoparticles and polyolefin adhesive onto substrates is introduced, which forms superhydrophobic coatings with a porous and hierarchical micro-/nanostructure. The resulting superhydrophobic coatings exhibit outstanding pressure resistance, maintaining a Cassie-Baxte state after 18 days of submersion in 1 m of water. Furthermore, the coatings demonstrate remarkable mechanical durability, withstanding 200 cycles of Taber abrasion, 100 cycles of tape-peeling, and 750g of sand abrasion. The coatings also show excellent chemical stability, enduring long-term immersion in corrosive liquids and 120 d of outdoor exposure. Additionally, the coatings display excellent anti-icing properties and can be applied to various substrate surfaces. This approach improves on the limitations of conventional superhydrophobic coatings and accelerates the application of superhydrophobic coatings in real-world environments.

Towards natural fibers resistant to mold and termites thanks to fluorine

Natural materials such as fibers or wood are increasingly used in different articles due to their bio-sourced and eco-friendly aspect. However, external aggression of termites and fungi limits their use or their lifetime, because of the deterioration of the materials structure that can be caused. In addition, because of the new legislation, some of preventive products are now forbidden due to their hazardousness. Therefore, in this study, we explore the possibility to perform a direct fluorination treatment in order to protect natural product from this external aggression. In addition, we also assess the potential resistance of these material to mould growth and termites attack after the application of two other fluorination-based treatments which take benefit of the formation of NaF and fluorinated silica nanoparticles.

Superhydrophobic coatings prepared from fluorinated silica nanoparticles and fluororesin: wetability, chemical stability, mechanical durability and water repellency

Superhydrophobic coatings prepared from fluorinated silica nanoparticles and fluororesin: wetability, chemical stability, mechanical durability and water repellency

Stretchable and Breathable Electroluminescent Displays Based on Ultrathin Nanocomposite Designs.

Stretchable electroluminescent devices represent an emerging optoelectronic technology for future wearables. However, their typical construction on sub-millimeter-thick elastomers has limited moisture permeability, leading to discomfort during long-term skin attachment. Although breathable textile displays may partially address this issue, they often have distinct visual appearances with discrete emissions from fibers or fiber junctions. This study introduces a convenient procedure to create stretchable, permeable displays with continuous luminous patterns. The design utilizes ultrathin nanocomposite devices embedded in a porous elastomeric microfoam to achieve high moisture permeability. These displays also exhibit excellent deformability, low-voltage operation, and excellent durability. Additionally, the device is decorated with fluorinated silica nanoparticles to achieve self-cleaning and washable capabilities. The practical implementation of these nanocomposite devices is demonstrated by creating an epidermal counter display that allows intimate integration with the human body. These developments provide an effective design of stretchable and breathable displays for comfortable wearing.

Facile Preparation of Impalement Resistant, Mechanically Robust and Weather Resistant Photothermal Superhydrophobic Coatings for Anti-/De-icing.

Photothermal superhydrophobic coatings hold great promise in addressing the limitations of conventional superhydrophobic anti-icing coatings. However, developing such coatings with excellent impalement resistance, mechanical robustness and weather resistance remains a significant challenge. Here, we report facile preparation of robust photothermal superhydrophobic coatings with all the above advantages. The coatings were prepared by spraying a dispersion consisting of fluorinated silica nanoparticles, a silicone-modified polyester adhesive and photothermal carbon black nanoparticles onto Al alloy plates followed by thermal curing. Thermal curing caused migration of perfluorodecyl polysiloxane from within the coatings to the surface, effectively maintaining a low surface energy despite the presence of the adhesive. Therefore, combined with the hierarchical micro-/nanostructure, dense yet rough nanostructure, adhesion of the adhesive and chemically inert components, the coatings exhibited remarkable superhydrophobicity, impalement resistance, mechanical robustness and weather resistance. Furthermore, the coatings demonstrated excellent photothermal effect even in the -10 °C, 80 % relative humidity and weak sunlight (0.2 sun) environment. Consequently, the coatings showed excellent passive anti-icing and active de-icing performance. Moreover, the coatings have good generalizability and scalability. We are confident that this study will accelerate the practical implementation of photothermal superhydrophobic coatings.

Dual-Coating of Fluorinated Polydimethylsiloxane/Fluorinated SiO2 Nanoparticles for Superhydrophobic and High-Efficiency Bacteriostatic Surface.

A simple two-step spray method is used to prepare superhydrophobic and bacteriostatic surfaces, involving dual-coating with polydimethylsiloxane-normal-fluorine (PDMS-NF) or branched-fluorine (PDMS-BF) in combination with fluorinated silica nanoparticles (FSiO2 -NPs) using a spray technique. This approach has the potential to create surfaces with both water-repellent and antimicrobial properties, which could be useful in a variety of applications. It is noteworthy that the dual-coating on cotton fabric exhibited an impressive dual-scale roughness and achieved superhydrophobicity with a water contact angle of 158° and a hysteresis of less than 3°. Additionally, the coating was subjected to an ultra-high concentration of bacteria (109 CFU/mL) and was still able to inhibit more than 80 % of attachment, demonstrating its effectiveness as a bacteriostatic surface.

Formation of Giant Unilamellar Vesicles Assisted by Fluorinated Nanoparticles.

In the quest to produce artificial cells, one key challenge that remains to be solved is the recreation of a complex cellular membrane. Among the existing models, giant unilamellar vesicles (GUVs) are particularly interesting due to their intrinsic compartmentalisation ability and their resemblance in size and shape to eukaryotic cells. Many techniques have been developed to produce GUVs all having inherent advantages and disadvantages. Here, the authors show that fluorinated silica nanoparticles (FNPs) used to form Pickering emulsions in a fluorinated oil can destabilise lipid nanosystems to template the formation of GUVs. This technique enables GUV production across a broad spectrum of buffer conditions, while preventing the leakage of the encapsulated components into the oil phase. Furthermore, a simple centrifugation process is sufficient for the release of the emulsion-trapped GUVs, bypassing the need to use emulsion-destabilising chemicals. With fluorescent FNPs and transmission electron microscopy, the authors confirm that FNPs are efficiently removed, producing contaminant-free GUVs. Further experiments assessing the lateral diffusion of lipids and unilamellarity of the GUVs demonstrate that they are comparable to GUVs produced via electroformation. Finally, the ability of incorporating transmembrane proteins is demonstrated, highlighting the potential of this method for the production of GUVs for artificial cell applications.

Increasing Functionality of Fish Leather by Chemical Surface Modifications.

Fish skin is a by-product of the fishing industry, which has become a significant environmental pollutant in recent years. Therefore, there is an emerging interest in developing novel technologies to utilize fish skin as a versatile raw material for the clothing and biomedical industries. Most research on finishing procedures is conducted on cattle leather, and practically very limited information on fish leather finishing is found in the literature. We have developed three functional surface finishing treatments on chromium (CL)- and vegetable (VL)- tanned salmon leather. These treatments include hydrophobic, oil repellent, and electro-conductive ones. The hydroxyl functional groups present on the surface of the leather were covalently grafted with bi-functional aliphatic small molecule, 10-undecenoylchloride (UC), by esterification reaction forming hydrophobic coating. The surface hydrophobicity was further increased via covalent binding of perfluorodecanethiol (PFDT) to the double bond end-groups of the UC-modified leather via thiol-ene click chemistry conditions. The oleophobic coating was successfully developed using synthesized fluorinated silica nanoparticles (FSN) and polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), showing oil repellency with a contact angle of about 100° for soybean oil and n-hexadecane. The electrically conductive coating was realized by the incorporation of conjugated polymer, polyaniline (PANI), via in situ polymerization method. The treated leather exhibited surface resistivity of about 5.2 (Log (Ω/square)), much lower than untreated leather with a resistivity of 11.4 (Log (Ω/square)).

The fluorinated SiO2 self‐assembly surface of epoxy resin with excellent insulating and superhydrophobic properties

AbstractThe flashover and dampness on the surface of epoxy resin (ER) composites are two critical factors leading to the failure of high voltage direct current (HVDC) insulating devices. Designing and constructing a surface structure with high insulating and hydrophobic performance is an effective way to solve these problems. In this paper, we prepared fluorinated silica nanoparticles (F‐SiO2) using a combination of dielectric barrier discharge (DBD) plasma and 1H,1H,2H,2H‐Perfluorodecyltrimethoxysilane (FAS‐17). The resulting low‐surface‐energy F‐SiO2 self‐assembled on the surface of ER to form a thin layer structure. Our results demonstrate a significant improvement in both the surface flashover voltage and hydrophobicity of ER composites with the self‐assembly structure. The maximum surface flashover voltage is increased by 35.73% to 12.08 kV, and the maximum water contact angle reaches superhydrophobicity at 155.5 ± 3°. The improvements in flashover voltage are attributed to changes in trap energy level and surface roughness. At the same time, the superhydrophobicity is due to the low‐surface‐energy characteristics and micro‐nano structure of the self‐assembly structure. This study provides a promising approach for synergistically improving flashover voltage and hydrophobicity of insulating materials.

Durable superhydrophobic coatings for prevention of rain attenuation of 5G/weather radomes

Superhydrophobic coatings are expected to solve the rain attenuation issue of 5G radomes. However, it is very challenging to design and construct such superhydrophobic coatings with good impalement resistance, mechanical robustness, and weather resistance, which remains as one of the main bottlenecks hindering their practical applications. Here, we report the design of superhydrophobic coatings with all these merits mentioned above by spray-coating a suspension of adhesive/fluorinated silica core/shell microspheres onto substrates. The core/shell microspheres are formed by phase separation of the adhesive and adhesion between the adhesive and fluorinated silica nanoparticles. The coatings have an approximately isotropic three-tier hierarchical micro-/micro-/nanostructure, a dense but rough surface at the nanoscale, and chemically inert composition with low surface energy. Consequently, the coatings show excellent impalement resistance, mechanical robustness and weather resistance compared with previous studies, and the mechanisms are revealed. Furthermore, we realize large-scale preparation, extension, and practical application of the coatings for efficiently preventing rain attenuation of 5G/weather radomes. By taking these advantages, we believe that the superhydrophobic coatings have great application potential and market prospect. The findings here will boost preparation and real-world applications of superhydrophobic coatings.

Highly durable, thermally stable, semi-transparent superhydrophobic surfaces for easy-cleaning of contaminants

With the development of smart electronic devices, the importance of surface-protective coatings is rapidly increasing. Superhydrophobic surfaces are promising protective coatings that exhibit potential for anti-wetting, self-cleaning, and antibacterial applications. However, their poor mechanical durability makes their practical application difficult. Additionally, rough surface geometries induce incident light scattering, thereby reducing the transparency and limiting their optical applications. This study describes semi-transparent superhydrophobic surfaces with improved mechanical strength and thermal stability obtained through simple spray coating. We mixed reactive polydimethylsiloxane (PDMS) as a binder with low surface free energy and high thermal resistance with fluorinated silica nanoparticles. PDMS polymers were functionalized to improve their hydrophobicity and adhesion properties through hydrosilylation with acrylate monomers. As a result, our superhydrophobic surfaces had a high-water repellency of above 160° and transparency of approximately 60 % at a wavelength of 550 nm. The coated surfaces exhibited an outstanding pencil hardness of 5H and sufficient clarity to identify objects through them. After heat treatment at 400 °C, the hardness increased to 6H while maintaining superhydrophobicity. Additionally, various contaminants were easily removed with water spraying. Our semi-transparent superhydrophobic surfaces can be widely applied in hard coatings for mobile displays, solar cell panels, self-cleaning paint, and outdoor facilities.

One-Step Process for the Fabrication of Hydrophobic and Dimensional Stable Wood Using Functionalized Silica Nanoparticles

The aim of this research was to improve the dimensional stability of wood through bulk hydrophobization, as a result of impregnation with fluorinated silica nanoparticles. The wood species European beech (Fagus sylvatica L.) and Scots pine (Pinus sylvestris L.) were used. The characterization of the modified wood was performed using analytical methods, including scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. The effect of fluorinated silica nanoparticles on the anti-swelling efficiency, water uptake, equilibrium moisture content, and water contact angle were investigated. The surface of the cell walls was discontinuously covered with fluorinated silica nanoparticles forming a rough surface coating. The presence of the hydrophobic silica nanoparticles improved the dimensional stability by permanently increasing the hydrophobicity of wood, besides a low weight percent gain. Furthermore, the treatment significantly decreased the equilibrium moisture content and water uptake. The modified wood surfaces showed significantly higher water contact angles, which was the main reason of the improved dimensional stability.

Superhydrophobic coatings from macromolecular fluorinated silica nanoparticles through START polymerization and “grafting onto” strategy

Fluorinated substances are often introduced to enhance the hydrophobicity of surfaces of various materials. In this work, fluorinated macromolecular coupling agents (AB)nA-b-PIPMSAm are prepared via successive step transfer-addition and radical-termination (START) polymerization and photocontrolled iodine-mediated reversible deactivation radical polymerization (RDRP) at room temperature, which is then decorated on the surface of silica nanoparticles followed by iodine removal for preparing iodine-free macromolecular fluorinated silica nanoparticles (macro-F-SiNPs-I). Superhydrophobic coatings were produced simply by spin coating of the macro-F-SiNPs-I onto glass or dip coating on cotton substrates. The effect of a variety of parameters on surface superhydrophobicity, such as the solvent for spinning coating, concentration of macro-F-SiNPs-I, size of silica nanoparticles and chemical structures of (AB)nA-b-PIPMSAm, were studied in detail, and the superhydrophobic surfaces with water contact angle (WCA = 172.6°) could be facilely achieved under optimum conditions. In addition, the resultant macro-F-SiNPs-I coatings are quite stable against acidic (pH = 1), basic (pH = 13) or high salty solutions, and their excellent superhydrophobic performance was also confirmed by self-cleaning and oil/water separation experiments, which displayed fascinating promise in practical applications on a large scale.

Facile fabrication of flexible superhydrophobic surfaces with high durability and good mechanical strength through embedding silica nanoparticle into polymer substrate by spraying method

Flexible superhydrophobic surfaces have been attracting more and more attention due to their foldable property. However, the superhydrophobic structure was easily damaged or destroyed owing to their poor interfacial force between substrate and superhydrophobic coating. Herein, fluorinated silica nanoparticles (F-SiO2) were sprayed onto the wet poly(amide–imide) (PAI) surface, which made F-SiO2 easily went into PAI substrate to enhance the durability of superhydrophobic surface. The PAI/F-SiO2 flexible surface exhibited a water contact angle (CA) of beyond 160° and a sliding angle (SA) of as low as 3°, while the tensile strength (34 MPa) was comparable to that of PAI substrate (35.8 MPa). Encouragingly, the superhydrophobicity and hierarchical porous structure of PAI/F-SiO2 surface were maintained even they were folded by 5000 times or underwent sandpaper abrasion test (500 cm of wear on a 1200 grit sandpaper under 50 g load), while the nanocomposites failed the sandpaper abrasion test when F-SiO2 were sprayed onto completely dried PAI surface. More importantly, the CA and SA just slightly decreased when PAI/F-SiO2 surfaces were heated at 300 °C for 24 h due to the unique surface morphology and high thermal stability of PAI, which is one of the highest thermal stabilities for flexible superhydrophobic films. In addition, PAI/F-SiO2 surfaces maintained superhydrophobic after hot water jet impact, acid–base immersing, UV irradiation, and ultrasonic treatment, indicating the fabricated surfaces could be used for practical application especially under harsh conditions. Furthermore, the superhydrophobic surfaces possessed icephobic properties. It should be noted that PAI/F-SiO2 surfaces showed such excellent properties, although their fabricating procedure did not undergo any optimization. This wet spraying method was also used to fabricate flexible superhydrophobic surfaces with other polymers as substrates such as poly(acrylic acid) (PAA), thermoplastic polyurethane (TPU), polystyrene (PS), and poly(vinyl alcohol) (PVA). Therefore, the simple strategy provided a general route to prepare flexible superhydrophobic films with high durability.

Water Recovery from Highly Saline Dye Wastewater by Membrane Distillation Using a Superhydrophobic SiO2/PVDF Membrane

Membrane distillation (MD) has been widely used for resource recovery from high-salinity wastewater, due to its superior technical merits of high separation efficiency and potential integration of low-grade heat. Herein, a robust superhydrophobic PVDF membrane prepared by spray-coating of fluorinated silica nanoparticles was employed to treat highly saline dye wastewater by MD. Specifically, impacts of operation conditions, including temperature difference, feed flow-rate, salinity, dye concentration, and dye species, on MD performance of the fabricated superhydrophobic PVDF membrane were comprehensively investigated. The increase of temperature difference and feed flow-rate had a positive effect on the MD flux of the membrane. Conversely, the rise in salinity and dye concentration induced an adverse impact on the MD flux. Furthermore, the superhydrophobic PVDF membrane showed a strong robustness in treating complex streams, as demonstrated by consistently stable MD flux using various dye/NaCl mixed solutions. Due to the robust surface superhydrophobicity, the fabricated PVDF membrane exhibited impressive antiwetting and antifouling properties against highly saline dye wastewater, consistently stable permeation flux, and high dye/salt removal efficiency (>99.99%). Moreover, the superhydrophobic membrane showed a high water recovery (90%) from highly saline dye wastewater with a slight reduction (13.4%) in permeation flux during a 39 h MD filtration. These results signify the promising practicability of the fabricated superhydrophobic PVDF membrane in sustainable management of highly saline dye wastewater via MD.

Extracellular pH Monitoring of Live Single Cells in Microdroplets Using Dual-Labelled Fluorinated Silica Nanoparticles and Time-Domain Dual Lifetime Referencing

Fluorinated silica nanoparticles doped with Ruthenium-tris-1,10-phenanthroline dichloride on the inside and covalently conjugated with perfluorooctyltriethoxysilane and fluorescein isothiocyanate on the outside were developed and served several functions; the fluorination of the particles served to stabilize droplets in a microfluidic system at their interface to the continuous phase for single-cell experiments, and the two dyes provided for intrinsically referenced pH readout according to the time-domain dual lifetime referencing scheme. Apart from eliminating the droplet-to-droplet transport, these nanoparticles at the interface of the droplets generated rigid substrates that were suitable for the proliferation of adherent cells in the droplets without additional matrices. Cancer and non-cancer cell lines with culture media were allowed to proliferate in the droplets and the extracellular pH was monitored. These nanoparticles used in a microdroplet system could measure the pH of the extracellular microenvironment of single cells and provide support for the growth of cells in droplets of around 50 µm diameter. The pHe showed 6.84 ± 0.04 and 6.81 ± 0.04 for cancer cells (MCF-7 and A549, respectively) and 7.36 ± 0.03 for healthy cells (HUVEC), after a 10-h incubation, which can be potentially applied in distinguishing tumor from non-tumor cells. Capable of assisting cell culture and pH sensing in droplet microfluidic systems, the dye-conjugated fluorinated nanoparticles described in this work offer possibilities in a variety of biochemical or environmental analytical applications.

Super-omniphobic surface prepared from a multicomponent coating of fluoro-containing polymer and silica nanoparticles

A multicomponent superomniphobic coating that can be applied to a broad range of substrates via simple spraying of a hybrid material system consisting of fluorinated poly[dimethylsiloxane-co-(3-aminopropyl) methylsiloxane (PDMS-F), fluorinated silica nanoparticles (FSiO2-NPs), and perfluoroalkyl polymer (F-Polymer). The PDMS-F was prepared by reacting the aminopropyl-containing copolymer of PDMS linear tridecafluoroheptanoic acid and branched heptafluoroisobutyrate respectively to yield the fluorinated polymer, named PDMS-NF and PDMS-BF respectively. By sequential spraying of PDMS-NF, FSiO2-NPs, and F-Polymer, the three-component omniphobic coating produces surface with lower contact angle hysteresis (CAH) (<15°) for most liquids, including water, hexadecane, glycol, ethanol, and diiodomethane, regardless of their polarity or surface tension. It can be applied on different substrates including fabrics, especially the cotton textile, which exhibits a static water contact angle (CA) of 163° and hexadecane (oil) CA of 153°.

Mechanically robust superamphiphobic ceramic coatings with releasable nanoparticle-capsules

Superamphiphobic surfaces that can keep surface clean even in severe oil pollution environments are attractive for many practical applications. Existing surfaces could achieve good environmental durability, but rarely anyone has demonstrated that coatings with mechanical robustness and superamphiphobicity were fabricated by simple fabrication processes. In this work, a new design of component phase separation on nanoparticle-capsules is proposed to generate durable superamphiphobic coatings by spray-coating the suspension of fluorinated nanoparticle powders and ceramic binders. During the process of film formation, the micro/nano composite structures appear on the surface by the stacking of agglomerates and nanoparticles. Meanwhile, the particles in the suspension can be reunited to produce plentiful particle-agglomerates in longitudinal direction driven by the difference of surface tension. And the agglomerates acted as particle-capsules are able to release the embedded fluorinated silica nanoparticles to the surface to regenerate superamphiphobicity instantaneously during physical wear. Moreover, the coatings are durable against physical abrasion of 500 Taber abrasion cycles under a load of 250 g, maintaining super-repellency to oils under comprehensive harsh conditions such as oil immersion, oil mist impact, and sand water stirring. This strategy is supposed to offer a new insight to development durable superamphiphobic coatings that can endure harsh operation environments for mechanical abrasion and chemical erosion.

A novel moisture-controlled siloxane-modified hyperbranched waterborne polyurethane for durable superhydrophobic coatings

Superhydrophobic coatings have attracted extensive interest owing to their excellent water repellence property. However, low durability, environmentally harmful fabrication methods, and complex fabrication methods severely limit their widely practical applications. In this work, we demonstrate an eco-friendly, robust, superhydrophobic matrix coating based on siloxane-modified hyperbranched waterborne polyurethane (Si-HBPU) in combination with fluorinated silica nanoparticles (F-SiO2). The superhydrophobic coating was constructed by convenient process of casting Si-HBPU onto the substrate, which was regulated by a moisture-controlled model, and then F-SiO2 nanoparticles were uniformly seeded onto the surface of semi-cured Si-HBPU. The Si-HBPU covalently bonds to F-SiO2 nanoparticles for the reason that Si-HBPU possesses many polar groups (such as Si-OH), which utilized the silanol groups to chemically bond with the surface hydroxyl of the substrate and F-SiO2 nanoparticles to form a solid SiOSi cross-linking network. The resulted coating exhibited an excellent water repellency with contact angles of ∼ 163° and sliding angles of ∼ 3°. And benefiting from the establishment of the stable SiOSi binding, the modified coating demonstrates excellent mechanical robustness, and is capable of maintaining superhydrophobicity after 140 cycles of sandpaper abrasion. The resultant coating shows excellent anti-icing/deicing performance: the water-freezing time can be postponed to 2205 s at −20℃ and the ice adhesion is significantly lower than that of a pure copolymer coating (∼21.2 KPa). Moreover, the Si-HBPU/ F-SiO2 coating also demonstrated excellence in scratch resistantance, anti-fouling and anti-corrosion performances. These remarkable performances may promote the development of large-scale operation and practical application.

Formulating A Novel Fluorinated Silica Nanoparticle using Fluoroalkylsilane as a Wettability Alteration Agent

A novel fluorinated silica nanoparticles were synthesized using 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS17) and further characterized to evaluate the wettability alteration capability. Previous research (1, 2) has utilized fluoroalkanoic acids as the coating agent. First, the in-situ functionalization method employs tetraethoxysilane (TEOS) as the silica precursor and water-soluble amine as the catalyst. It is then further functionalized with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (FAS17) with ethanol to attain the novel fluorinated silica nanoparticles. The preliminary characterization from FTIR analysis indicated that the in-situ functionalization was successfully applied. The new bonding formation with fluorine attachment on the novel fluorinated silica nanoparticles is capable to alter the wettability of the solid surface, exhibiting self-cleaning properties.