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The scientific fraternity and coating companies have researched and developed coatings with superhydrophobic features for a wide range of applications, varying from automotive, oceanic, pharmaceutical, and thermal and power sectors, over the preceding few years. The self-cleaning features of superhydrophobic surfaces exhibit pronounced dust repelling and lower dust adhesiveness qualities, along with incomparable water repellence for maritime, automotive, and pharmaceutical applications. The advancement of super-hydrophobic surfaces for averting the accrual of impurities on surfaces is an active space of exploration globally. A lesser hysteresis of contact angle leads to drops of water sliding effortlessly on such surfaces. The solid surfaces’ surface energy can be weakened by fixing materials of lesser surface energy on the exterior, which can be performed by the following dual methods; either by fixing materials of reduced surface energy straight onto the exterior of a substrate in the form of a coating of that material, or by fixing materials of less surface energy on the exterior of nano-architectural structures and then dropping the coating of those nanoscale materials on the exterior of the substrate. The generation of nanoscale irregularities on substrates by dropping nanostructure layers on surfaces makes it an attractive option since, usually, nanomaterials have a minimum of one dimension, ranging from 1 - 100 nm. The nanostructures’ sizes unveil exceptional physical and chemical characteristics, principally owing to their greater specific surface area to volume quotient. This review encompasses the non-fluorinated superhydrophobic coatings developed to date.

Environmental and health concerns are driving food packaging to reduce the use of poly- or perfluorinated compounds and petroleum-based polymers. Here, we successfully obtained good oil-proof paper by combining cellulose nanofibril (CNF) film with filter paper through film transfer. The process was not only facile but also did not require chemical reagents other than water. To achieve the kit number 12, the basis weight of the CNF film was 2.1 g/m2, which was much less than the amount required for coating. The calendering process further reduced the pores thus improving the oil resistance of the film transfer paper. At a calendering pressure of 20 N/mm, only 1.4 g/m2 of the CNF film was required for kit number 12. This study provides a new way for the application of CNF in the field of oil resistance.

A novel eco-friendly and durable superhydrophobic and flame-retardant cotton fabric with fluorine-free, halogen-free was prepared via step-by-step dip-coating and spraying technology. At first, common cotton fabric was impregnated in the flame-retardant ethoxysilane-terminated phosphate polyurethane. Afterwards, methanol mixture containing silica nanoparticles, methyl triethoxysilane, and dihydroxy-terminated polydimethylsiloxane was sprayed on the surface of the cotton fabric. Finally, a flame-retardant cotton fabric with micro-nano rough surface and low surface energy was formed. The resulting superhydrophobic and flame-retardant cotton fabric exhibited superamphiphobicity with the contact angle and sliding angle of 160° and 6°, respectively, while flame retardancy with limited oxygen index of 28.1%. and flame self-extinguishing. Furthermore, this superhydrophobic and flame-retardant cotton fabric showed robust superhydrophobicity and flame-retardancy after undergoing 1000 cycles of abrasion, 60 min of ultrasonic washing and 50 standard machine washing cycles, in sequence, indicating its potential as a multifunctional protective textile fabric. Additionally, the method proposed in this study can effectively solve durability and environmental problems currently faced by the coated fabric with superhydrophobicity and flame-retardancy.

We introduce a superhydrophobic surface that is composed of homogeneous polystyrene (PS) raspberry nanoparticles of around 50 nm diameter, via a convenient single-step scalable synthesis method. Th...

In this work, the hollow rectangular prism-like TiO2 (HRP-TiO2) mesocrystals with exposed {001} facets were synthesized via an in-situ hydrothermal process without introducing any additional hydrof...

Superhydrophobic coatings have received considerable attention owing to their potential applications. There has been an increasing demand for the construction of durable superhydrophobic coatings u...

Coated paper substrates are used for a wide range of applications. The biggest challenge that remains unsolved with regard to coated paper is its recyclability. Herein, we report a unique approach ...

Waterproof and breathable membranes (WBMs) with simultaneous environmental friendliness and high performance are highly desirable in a broad range of applications; however, creating such materials still remains a tough challenge. Herein, we present a facile and scalable strategy to fabricate fluorine-free, efficient, and biodegradable WBMs via step-by-step dip-coating and heat curing technology. The hyperbranched polymer (ECO) coating containing long hydrocarbon chains provided an electrospun cellulose acetate (CA) fibrous matrix with high hydrophobicity; meanwhile, the blocked isocyanate cross-linker (BIC) coating ensured the strong attachment of hydrocarbon segments on CA surfaces. The resulting membranes (TCA) exhibited integrated properties with waterproofness of 102.9 kPa, breathability of 12.3 kg m-2 d-1, and tensile strength of 16.0 MPa, which are much superior to that of previously reported fluorine-free fibrous materials. Furthermore, TCA membranes can sustain hydrophobicity after exposure to various harsh environments. More importantly, the present strategy proved to be universally applicable and effective to several other hydrophilic fibrous substrates. This work not only highlights the material design and preparation but also provides environmentally friendly and high-performance WBMs with great potential application prospects for a variety of fields.

Aqueous film-forming foams (AFFFs) are widely used to extinguish liquid fires due to their film-forming properties. AFFF formulation historically contains per- and polyfluoroalkyl substances (PFASs) that can be very persistent and pose a health risk to biota and humans. Detailed analysis of the chemical composition of AFFFs can provide a better understanding on the potential environmental impact of the ingredients. In this study, a novel workflow combining target analysis, nontarget screening analysis (NTA), total fluorine (TF) analysis, and inorganic fluoride (IF) analysis was applied to disclose the chemical composition of 24 foams intended for liquid fires. Foams marketed as containing PFASs as well as fluorine-free foams were included. By comparing the sum of targeted PFASs and total organofluorine concentrations, a mass balance of known and unknown organofluorine could be calculated. Known organofluorine accounted for1% in most fluorine-containing AFFFs, and it was confirmed that the foams marketed as fluorine-free did not contain measurable amounts of organofluorine substances. Five fluorinated substances were tentatively identified, and non-fluorinated zwitterionic betaine compounds, which are considered to be replacement substances for PFASs, were tentatively identified in the organofluorine-free foams.

A new type of superhydrophobic borneol-based polymeric coating has been prepared. The chemical composition of the polymer particles was analyzed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, which showed that the polymer did not contain fluorine, which can effectively avoid the cytotoxic risk of fluorine. By dynamic light scattering, scanning electron microscopy, and static contact angle measurement, the contact angle of the prepared coating gradually increased with increasing diameter of the polymer particles, and a superhydrophobic coating surface was finally obtained. Interestingly, after dissolving the superhydrophobic sample with tetrahydrofuran and making it a normal hydrophobic sample, the antiadhesion performance for E. coli was greatly reduced, and it could not effectively prevent E. coli adhesion. In addition, a long-term antiadhesion study of bacteria was performed. The superhydrophobic borneol-based polymer coating showed long-term resistance to E. coli adhesion. Therefore, the excellent antibacterial properties and cell compatibility mean that this series of polymer materials has great potential in the field of biomedicine.

The fluorine-free metal–organic decomposition (FF-MOD) route is one of the table-top methods for the growth of high-quality superconducting YBa2Cu3O7−δ (YBCO) films due to its advantages of being e...

Traditional superhydrophobic materials for oil/water separation not only depend on nonrenewable feedstocks but also lead to secondary environmental pollutions after discarding, due to the presence ...

Although artificial superhydrophobic materials have extensive and significant applications in antifouling, self-cleaning, anti-icing, fluid transport, oil/water separation, and so forth, the poor robustness of these surfaces has always been a bottleneck for their development in practical industrial applications. Here, we report a facile, economical, efficient, and versatile strategy to prepare environmentally friendly, mechanically robust, and transparent superhydrophobic surfaces by combining adhesive and hydrophobic paint, which is applicable for both hard and soft substrates. The coated substrates exhibit excellent superhydrophobic property and ultralow adhesion with water (contact angle ≈ 160° and sliding angle

This study is aimed at the fabrication of superhydrophobic fluorine-free films on cotton fabrics through incorporating a rough sub-structure followed by chemical modification. Stable titania hydrosols were prepared via sol-gel using 0.44 mol/L titanium tetraisopropoxide in acidic media followed by chemical modification of the sol using vinyltrimethoxysilane (VTMS) for surface energy reduction and spraying over the surface. Upon drying at 60 °C, covalent attachment of vinyl modified TiO2 particles to hydrophilic surface was occurred. Water contact angle increased from 0° on pure fabric up to 134.1° with sliding angles >90°. Further enhancement in water contact angles up to ∼170° and reduction of sliding angle to

Water- and oil-resistant materials are useful for many applications, but turning polar and porous cellulosic substrates such as paper, corrugated board, cardboard, and fabrics into a water- and oil...

This research presents the development of novel self-cleaning cotton fabric with dual functionalities of superhydrophobicity and photocatalytic activity. Fluorine-free coating formulations composed of either flower-like TiO2 or nitrogen-doped TiO2 particles, with a hierarchical surface morphology, and polydimethyl siloxane (PDMS) polymer were applied to cotton fabrics using a facile dip-coating method. The self-cleaning performance of fabrics was assessed based on their superhydrophobicity and effective removal of oil-based food stains. Additionally, the impact of nitrogen doping on photocatalytic activity of flower-like TiO2 particles was investigated. The obtained results demonstrated that the presence of both PDMS and hierarchical particles generated excellent superhydrophobicity on the cotton fabric with a water contact angle of 156.7 ± 1.9⁰. In addition, the coated fabric exhibited highly efficient photocatalytic activity, decomposing stains under simulated sunlight. Nitrogen doping process significantly boosted the photocatalytic activity of TiO2 particles in degrading stains and dye solution. The developed superhydrophobic fabric showed high robustness against both chemical and physical durability tests. This research contributes significantly to the continued advancement of highly efficient self-cleaning textiles via the development of dual functions of superhydrophobicity and photocatalytic activity.

Although various superhydrophobic materials have been manufactured and effectively used for oil&ndash, water separation, it is still highly desirable to explore materials which are eco-friendly, low-cost, and multifunctional. In this paper, a stable copolymer solution was prepared from the fluorine-free superhydrophobic copolymer with dual-responsiveness of temperature and pH. The functional superhydrophobic paper was prepared by immersing paper in copolymer solution by the dip-coating method. The surface element and structure analysis of the prepared superhydrophobic paper shows that the dual-responsive copolymer adheres successfully to the surface of the paper without destroying the fiber structure of the paper. At pH &ge, 7 and T &gt, 25 &deg, C, the paper has a good superhydrophobic performance, while under the conditions of pH &lt, 7 and T &lt, C, the paper comes into a hydrophilic state. Therefore, the dual-responsive superhydrophobic paper is more likely to adapt to the complicated oil-water separation environment than the single-response.

Inspired by natural living things such as lotus leaves and pitcher plants, researchers have developed many excellent antifouling coatings. In particular, hot-water-repellent surfaces have received much attention in recent years because of their wide range of applications. However, coatings with stability against boiling in hot water have not been achieved yet. Long-chain perfluorinated materials, which are often used for liquid-repellent coatings owing to their low surface energy, hinder the potential application of antifouling coatings in food containers. Herein, we design a fluorine-free slippery surface that immobilizes a biocompatible lubricant layer on a phenyl-group-modified smooth solid surface through OH-π interactions. The smooth base layer was fabricated by modification of phenyltriethoxysilane through a sol-gel method. The π-electrons of the phenyl groups interact with the carboxyl group of the oleic acid used as a lubricant, which facilitates immobilization on the base layer. Water droplets slid off the surface in the temperature range from 20 to 80 °C at very low sliding angles (2°). Furthermore, we increased the π-electron density in the base layer to strengthen the OH-π interactions, which improved long-term boiling stability under hot water. We believe that this surface will be applied in fields in which the practical use of antifouling coatings is desirable, such as food containers, drink cans, and glassware.

In recent years, a great many wonderful works on fluorine-free superhydrophobic coatings have been reported. However, the detailed review is rare. Herein, the research progress on superhydrophobic coatings from non-fluorinated polydimethylsiloxane (PDMS) was summarized, including fabrication methods and their applications. The methods were compared in terms of instruments, handling, and substrates, etc. Moreover, advantages and disadvantages were summarized. It should be noticed that these methods are not only suitable for fabrication of PDMS based superhydrophobic coatings, but also useful in coatings composed from the other non-fluorinated compounds, such as wax, long-chain alkane, and carbon nanomaterials. The various methods and their combination provide researchers and engineers a vast array of choices to fabricate fluorine-free superhydrophobic coatings. It is believed that this review is a good reference to those devoting in development of fluorine-free superhydrophobic coatings of excellent performances.

Water-repellent finishing of cotton fabrics was carried out using fluorine-free functionalized silsesquioxanes. The modification was performed in two stages: (i) preparation of alkylfunctionalized silsesquioxanes bearing additional triethoxysilyl groups by way of a photochemical thiol-ene click reaction, and (ii) modification of the cotton fibers with these silsesquioxane derivatives. Different ratios of functional groups were investigated and compared with regard to their influence on hydrophobic properties. The hydrophobicity of the cotton fabric was evaluated using the water contact angle test (WCA). Changes in the surface morphology were examined by scanning electron microscopy and atomic force microscopy. In addition, the elemental composition of the treated fabrics was analyzed by energy-dispersive spectroscopy. The most effective and durable derivatives appeared to be those containing four dodecyl groups and four triethoxysilyl groups. The treated surface with WCA of 146° and low roll-off angle (approaching the level of superhydrophobicity) demonstrated considerably higher durability after multiple standard washing cycles.

We report a facile method towards synthesis of fluorine free superhydrophobic mesoporous silica particles. Silica particles were prepared from rice husk (RH) as the silica source and CTAB as the structure directing agent. The as-prepared hydrophilic silica particles were converted to superhydrophobic structures by silane treatments. Silane treatment enhanced the wetting nature of the silica material from 60° to

Cotton fabrics with durable hydrophobic properties were prepared by a novel method of thiol-ene click reaction. In this study, cotton fabrics were firstly treated with 3-Mercaptopropyltriethoxysilane (KH-580) to graft thiol-reactive groups on the cotton surface. Then, these groups could react with vinyl-POSS and 1-dodecanethiol under UV irradiation. The results show the cotton fabric has been covered by the micro-nanostructure of water repellent layer with water-contact angle of ∼149.2° which approaches the level of superhydrophobicity. After 30 cycles of standard washing citing AATCC 61-2007, water-contact angle still remains ∼146.3°, indicating this method can be applied to cellulose fibers with durable water repellent properties.

Rechargeable metallic lithium batteries are considered as promising candidates for next-generation energy storage due to their high energy densities. However, safety concerns associated with electrolyte flammability and dendrite growth hinder their practical applications. Nonflammable liquid electrolytes have attracted significant attention recently, but they are mainly based on expensive ionic liquids, fluorinated solvents, or with highly concentrated salt. Here we design a novel trisalt electrolyte composed of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-lithium bis(oxalato)borate (LiBOB)-LiPF

The microstructural properties of F-free slag, the CaO–SiO2–TiO2 (CST) systems, are investigated by molecular dynamics (MD) simulations. The results show that in the CST system, the average bond length of Si–O remains in 1.61 A. The addition of TiO2 contributes to the increase in the concentrations of 4-coordinated Si and 4-coordinated Ti. Increasing the amount of CaO decreases the proportion of bridging oxygen (BO) atoms and the degree of network connectivity (Q3 and Q4), suggesting the simplification of melt polymerisation. Substituting CaO with SiO2 and maintaining a constant TiO2 level causes the microstructure of the slag to become more complex. Both SiO2 and TiO2 contribute to the more complex structures of the melts. Simultaneously, Si–O–Ti linkages are more favourable than Si–O–Si or Ti–O–Ti linkages. Thus, TiO2 is regarded as network former in terms of its structure within CST system when the content of TiO2 excessed 28 mass%.

In this work, non-particle and fluorine-free superhydrophobic films were constructed on mild steel (MS) for corrosion protection by one-step electrodeposition from dodecyltrimethoxysilane (DTMS)-contained precursor solution. The superhydrophobicity was achieved by the generated micro/nanostructure of hydrophobic DTMS during electrodeposition. The superhydrophobic films exhibited long-term stability to air atmosphere. The protective performance in 3.5 wt. % NaCl solution was estimated by potentiodynamic polarization technique, by electrochemical impedance spectroscopy, by monitoring water contact angle changes and by iron dissolution examination. The results show that the superhydrophobic films exhibit remarkable enhanced anticorrosion performance for MS with a promising inhibition efficiency of 99.74%.

The fluorine bearing and free silicate melts of Na2O-K2O-SiO2-CaF2 system were treated under ultrasonic field, and the melt structure and viscosity were measured. The results showed that the fluorine bearing silicate melt can be depolymerized and the polymerization decreased with the ultrasonic intensity. The viscosity of the fluorine bearing silicate melt decreased more quickly to the dynamic balance point between the dissociation and reconnection of the species, and reverted more slowly to the natural state than the fluorine free silicate melt, because fluorine ions join the silicate network via the formation of new Si-F bonds. The formation of Si F bonds can intensify the reduction of the viscosity, but the consumption of fluorine ions may lead to an increasing of the viscosity, which resulted in the weak decreasing trend in the viscosity as the ultrasonic intensity increased. The method may be helpful in assisting the synthesis of fluorine bearing bioactive glass.

Recently, fluorine materials have been a serious cause of environmental concern. In response, a novel fluorine-free superhydrophobic coating is presented in this paper. A superhydrophobic coating based on silicone and surface-modified colloidal silica is explored and exploited. First, a superhydrophobic coating, based on silicone resins and fluorine group-modified colloidal silica, is developed. Then, the fluorine group-modified colloidal silica is replaced by octyl-modified colloidal silica, a superhydrophobic coating based on fluorine-free materials, octyl-functionalized colloidal silica, and epoxy-modified silicone. The hydrophobicity and coating integrity were investigated, and the fluorine-free coating shows good superhydrophobicity and coating integrity. The result demonstrates the feasibility of a fluorine-free superhydrophobic coating, thus providing an effective solution to the environmental problems caused by fluorine chemicals.

In this paper, an intensive study is performed to elucidate the link between sinter temperature and sinter atmosphere as processing parameters in YBCO film formation, starting from an aqueous fluorine-free AWAT CSD precursor. Moreover, the results are linked to the reaction mechanism behind this non-fluorine approach. This resulted in a partial oxygen versus temperature diagram containing different zones giving rise to specific YBCO properties. It is observed that sinter temperature and sinter atmosphere should be judiciously chosen to obtain high quality superconducting films. Under a 200 ppm O2 atmosphere, highly textured YBCO films are obtained when sintering took place at 815 °C giving rise to an inductive Tc,onset of 92 K and a Jc-value up to 1.1 MA cm−2. Moreover, this paper gives a clear indication that the formation of a liquid phase strongly enhances the epitaxial growth.

We present a simple, environmentally friendly approach to fabricating superhydrophobic coatings with pH-induced wettability transition. The coatings are prepared from a mixture of silica nanoparticles and decanoic acid-modified TiO2. When the coating is applied on cotton fabric, the fabric turns superhydrophobic in air but superoleophilic in neutral aqueous environment. It is permeable to oil fluids but impermeable to water. However, when the coated fabric is placed in basic aqueous solution or ammonia vapor, it turns hydrophilic but underwater superoleophobic, thus allowing water to penetrate through but blocking oil. Therefore, such a unique, selective water/oil permeation feature makes the treated fabric have capability to separate either oil or water from a water–oil mixture. It may be useful for development of smart oil–water separators, microfluidic valves, and lab-on-a-chip devices.

The influence of the CaO/SiO2 ratio on flux viscosity at 1300°C, break temperature and crystallization was investigated.

YBa₂C₃O 7-x films were fabricated on a SrTiO3 (100) substrate using a trimethylaceate propionic acid (TMAP)-based MOD process by controlling the precursor solution viscosity, firing temperature, and by using various coatings. The viscosity of the precursor solution was controlled by the addition of Xylenes. The films were heat treated with different temperatures from 750 to 800 ℃. c-axis oriented films were obtained. After adding 9 ㎖ of Xylene into the precursor solution, the T c of the YBCO film, which was coated 2 times and heat treated at 800 ℃, was 86 K and the measured J c was above 2.5 MA/㎠ at 77 K in a zero-field.

This paper investigates the dynamic surface tension of aqueous film forming (AFFF) and fluorine-free (FF) foam solutions by pendant drop tensiometry. Additional experiments are conducted to measure the interfacial tension between the foam solutions and two hydrocarbon liquids, n-heptane and diesel oil. The pendant drop technique yields both surface and interfacial tension at time scales ranging from seconds to hours, being limited at the lower end by the time necessary to form a droplet, and at the upper end by the evaporation of the droplet's material. The results indicate that the surface tension of AFFF formulations, diluted at the design concentration, rapidly reaches its equilibrium value. However, the approach to equilibrium is slowed down by additives, such as xanthan gum, present in the alcohol tolerant concentrates (ATC-AFFF). FF solutions show a slower approach to static values than AFFF formulations. At the design dilution, and at room temperature, these static values are in the order of 27 mN m -1, as compared to 16 mN m -1 for AFFF solutions. The measurements of the interfacial tension indicate rapid attainment of equilibrium for both AFFF and FF formulations, with the static values of around 2 and 0.9-2.5 mN m -1, for AFFF and FF, respectively. With the surface tension of n-heptane and diesel oil of 20.1 and 28.3 mN m -1, the spreading coefficient of FF formulations for the present systems varies between -9.4 and 0.6 mN m -1. These results indicate that film formation does not play a role during fire suppression by FF foams.