High Hydrophobic Properties Research Articles

Application of Low-Temperature Postradiation Polymerization of Polytetrafluoroethylene for Hydrophobization of Porous Ceramic Materials Based on Oxide Fibers

Porous ceramic materials based on oxide fibers, which have lower specific density and thermal conductivity, are able to function at temperatures exceeding 1000°C, including in an oxidizing atmosphere, which allows this class of materials to have a wide range of applications in various industries. The disadvantage of such materials is the hydrophilicity caused by the chemical composition of the fibers and the highly developed porous structure, which severely limits their use, particularly in arctic and subarctic climates characterized by high humidity. The authors have investigated and proposed a method of hydrophobization using the technology of low-temperature postradiation graft polymerization of tetrafluoroethylene molecules. The technology makes it possible to apply polymer coatings to oxide fibers, providing high hydrophobic properties, which is manifested in the increased value of the contact angle of wetting the surface of the material, which in turn substantially improves their operational characteristics and expands the possibilities of practical application as heat-shielding and heat-insulating materials.

Halide perovskite based on hydrophobic ionic liquid for stability improving and its application in high-efficient photovoltaic cell

A novel ionic liquid, 3-(3-aminopropyl)-1-methylimidazolium hexafluorophosphate (APMimPF6), with high hydrophobic property was successfully applied as the functional monomer for the halide perovskite preparation. The new hydrophobic ionic liquid significantly facilitates the perovskite forming a 2-dimensional structure with good passivation, particularly at the grain boundaries because of the high hydrophobic character and large size of ionic liquid molecule. The perovskite solar cell fabricated with this new perovskite based on the hydrophobic ionic liquid was found possessing excellent properties: the maximum value of Jsc = 22.9 mA cm−2, Voc = 1.05 V, and PCE = 17.3%. In addition, the perovskite solar cell also shows good long-term stability, which benefited from the protecting effect of the high hydrophobic ionic liquid. In a typical stability test, the cells stored under the conditions with a relative humidity of 57% for 40 days, the PCE was able to retain 98% of its initial value. Therefore, the present study demonstrated a significant protocol for the development of highly stable perovskite solar cells.

Self-propagating high temperature synthesis of composite materials based on boron carbide

The creation of coatings with high hydrophobic properties has now emerged as a separate area of modern materials science, since it is necessary to analyze the processes taking place in nanoscale systems, and, in particular, nanotechnologies open up fundamentally new possibilities for controlling the surface properties of materials. It is stated that the main requirement necessary for obtaining the superhydrophobic state of the surface of materials is to provide roughness of the surface and mechanical strength of the texture used for this. In addition, it is possible to use composite compositions, whereby it is possible not only to impart hydrophobicity to the surface texture, but also to chemically bind it to the surface ofthe substrate, thereby increasing the stability of the hydrophobic coating under operating conditions

Low dielectric constant silica-containing cross-linked organic-inorganic materials based on fluorinated poly(arylene ether)s

In this work, for the first time, we describe the design and synthesis of novel fluorinated poly(arylene ether)/silica cross-linked materials (FPAE/SiO1.5) through a sol-gel process by using the triethoxysilyl-containing fluorinated polyethers as precursors for both organic and inorganic networks formation. The polyether-based precursors with the sol-gel active species were synthesized via hydrosilylation reaction between triethoxysilane and the corresponding allyl-functionalized FPAE under Pt catalysis. Herein, we present two approaches of hydrolysis triethoxysilane groups to silanol ones within sol-gel chemistry: (1) hydrolysis with air moisture and (2) hydrolysis of the ethoxysilyl groups at the interface between two liquids. The mechanical and thermal properties of the FPAE/SiO1.5 materials were studied depending on the structure of macromolecular chains and synthetic route. Scanning electron and atomic force microscopies were employed to investigate the morphology of the resulting silica-containing cross-linked materials. The resulting FPAE/SiO1.5 films were flexible and tough with tensile strength above 25 МPа, and exhibited high thermal stability, having the initial decomposition temperature about 300°С. For more detailed explanation of the thermophysical behavior of the FPAE/SiO1.5 materials, the synthesis method of new silica-containing organic-inorganic system was developed by the direct hydrosilylation reaction between allyl-functionalized polyethers and 1,1,3,3-tetramethyldisiloxane. All films exhibited high hydrophobic properties (water contact angles above 102°), low dielectric constants and losses at room temperature. In particular, the FPAE/SiO1.5 film prepared from tetrafluorobenzene-based polyether showed the ultra-low dielectric constant of 1.86 at 10 kHz. This makes the obtained polymer FPAE/SiO1.5 materials attractive for microelectronics and many other emerging applications.

Isolation and Identification of Potent Probiotics with High Lead Removal Capability

Probiotics play an effective and significant role in human health. The aim of this study was to isolate potential probiotics from Egyptian sources. Among the 14 different bacterial isolates recovered from 8 different sources on Man-Rogosa-Sharp (MRS) agar medium, 5 isolates exhibited tolerance to pH 3 and survived at bile concentration of 0.3% for 3h. The selected isolates were resistant to amikacin, vancomycin, ciprofloxacin and bacitracin. In addition, they showed high antibacterial activity against 7 pathogens. Hydrophobicity usingxylene and toluene showed high hydrophobic property for M isolate with toluene and xylene (80.43±0.95% and 78.2±0.73%, respectively). The potent isolate was identified by 16S rRNA gene as Lactobacillus plantarum strain M (KY508300). This strain was able to remove 71.28 ± 0.4 % of lead (1mg/ml) after 5min. The probiotic strain M showed count stability in yoghurt up to 21 days. The characteristic features of L. plantarum strain M as potent probiotics entitled it to be used in industrial and environmental applications.

Surface Nanostructuration and Wettability of Electrodeposited Poly(3,4-ethylenedioxypyrrole) and Poly(3,4-propylenedioxypyrrole) Films Substituted by Aromatic Groups.

In the aim to obtain parahydrophobic materials (both high contact angles and high hysteresis) for possible applications in water harvesting systems, we report the synthesis of novel 3,4-ethylenedioxypyrrole (EDOP) and 3,4-propylenedioxypyrrole (ProDOP) monomers with aromatic rings on the 3,4-alkylenedioxy bridge and the resulting conducting polymer films were prepared by electropolymerization. We show that the surface properties can be tuned by the nature of the aromatic ring (phenyl, biphenyl, diphenyl, naphthalene, fluorene, and pyrene) and the polymerizable core (EDOP or ProDOP). The best results are obtained with both EDOP and diphenyl, with which extremely high hydrophobic properties (up to 116°) are obtained, even if the polymers are intrinsically hydrophilic. These surfaces could be applied in the future, for example, in water harvesting systems or in water/oil separation membranes. The synthesis strategy is extremely interesting, and many other molecules will be envisaged in the future.

The Effect of Hydrophobicity of Ammonium Salts on Stability of Quasi‐2D Perovskite Materials in Moist Condition

AbstractWith the potential of achieving high efficiency and low production costs, perovskite solar cells (PSCs) have attracted great attention. However, their unstableness under moist condition has retarded the commercial development. Recently, 2D perovskites have received a lot of attention due to their high moisture resistance. In this work, four quasi 2D quasi perovskites are prepared, then their stability under moist condition is investigated. The surface morphology, crystal structure, optical properties, and photovoltaic performance are measured. Among the four quasi‐2D perovskites, (C6H5CH2NH3)2(FA)8Pb9I28 has the best performance: uniform and dense film, extremely well‐oriented crystal structure, strong absorption, and a high power conversion efficiency (PCE) of 17.40%. The aging tests show that quasi‐2D perovskites are more stable under moist conditions than FAPbI3 is. The (C6H5CH2NH3)2(FA)8Pb9I28 quasi‐2D perovskite devices exhibit high humidity stability, maintaining 80% of the starting PCE after 500 h under 80% relative humidity. Compared with other quasi‐2D perovskites, (C6H5CH2NH3)2(FA)8Pb9I28 has the highest humidity stability, due to their strongest hydrophobicity from C6H5CH2NH3+. This work demonstrates that the properties of perovskite materials can be modified by adding different ammonium salts into FAPbI3. Thus, by introducing ammonium salts with high hydrophobic properties the fabrication of highly efficient and stable 2D PSCs may be possible.

Study of the Gemini Surfactants' Self-Assembly on Graphene Nanosheets: Insights from Molecular Dynamic Simulation.

Understanding the mechanism of adsorption and self-assembly of surfactants on graphene is highly important to perform better optimization of the graphene dispersion process. Because of Gemini surfactants' special structure, they have a high charge capacity, high hydrophobicity, and unique self-assembly properties compared to single-chain surfactants. Therefore, Gemini surfactants with their small concentrations are expected to disperse and stabilize graphene nanosheets in aqueous solutions more effectively. We conducted molecular dynamics simulations to study adsorption and self-assembly of single-chain cationic surfactant dodecyltrimethylammonium bromide (C12TAB) and its same family Gemini surfactant dimethylene-α,β-bis(dodecyldimethylammonium bromide) ([12-2-12]Br2) on graphene nanosheets. The results showed that assemblies morphology formed on graphene is affected by surfactant structure. We observed that increasing surface coverage, especially for [12-2-12]Br2, leads to a transmission in adsorption mechanism and most [12-2-12]Br2 head groups tend toward the aqueous phase and prevent water molecules from accessing graphene surface. It can be concluded from morphological assessments that [12-2-12]Br2 is more effective than C12TAB in stabilizing graphene aqueous suspensions. Moreover, we investigated the effect of graphene sheet size and Gemini surfactant spacer length on the structure of surfactant assemblies on graphene. The present study results can expand our comprehension of dispersion mechanism of graphene nanosheets by Gemini surfactants.

Facile fabrication of asphaltene-derived graphene-polyurethane sponges for efficient and selective oil-water separation

ABSTRACTBased on the natural graphene-structure in the raw asphaltene material, a graphene-polyurethane sponge (GPU) oil-absorption material was prepared via a facile and inexpensive route of dip-coated sponge carbonization, which used low-value petroleum asphlatene as the dip-coating reagent and polyurethane sponges as the template. The GPU presents high hydrophobic and super oleophilic properties, as well as the excellent oil absorption performance. And its chloroform absorption capacity could reach 123 times its original mass, which is significantly higher than that of most reported oil absorbents. Furthermore, the GPU exhibits good recyclability. It has the promising applications in the pollution control of spilt oil.

Hydrophobic modification of nanoscale zero-valent iron with excellent stability and floatability for efficient removal of floating oil on water

Usually, nanoscale zero-valent iron (NZVI) cannot float on water because of high density and hydrophilic surface. Herein, alkyltrimethoxysilanes with different carbon chain lengths (C1, C8 and C16) were used as “water-repellent legs” to graft onto NZVI, enduing NZVI with hydrophobic and floatable characteristics like a water strider. The hydrophobic performance of as-modified NZVI materials was found to be better when NZVI was modified by alkyltrimethoxysilane with longer carbon chain, and a large contact angle of 151.2°(>150°) was obtained in C16-NZVI, indicating the superhydrophobic characteristic of C16-NZVI. The oil-absorption experiments showed that the absorption capacity of C16-NZVI for lubricating oil reached 9.73 g/g within 30 s. After seven consecutive runs, the oil-absorption capacity of C16-NZVI still maintained at 9.26 g/g, indicating high reusability of C16-NZVI. Also, C16-NZVI exhibited excellent stability in NaCl solution without being oxidized for 32 d. Significantly, C16-NZVI possessed admirable chemical stability with high hydrophobic property in acid and alkaline solutions (pH 3–12). Considering the advantages of easy preparation, high stability and reusability, excellent oil-absorption capacity as well as magnetic recovery property, C16-NZVI is expected to have remarkable potential in the treatment of floating oil on water/seawater.

Impaired Ciliogenesis in differentiating human bronchial epithelia exposed to non-Cytotoxic doses of multi-walled carbon Nanotubes

BackgroundMulti-walled carbon nanotubes (MWCNTs) are engineered nanomaterials used for a variety of industrial and consumer products. Their high tensile strength, hydrophobicity, and semi-conductive properties have enabled many novel applications, increasing the possibility of accidental nanotube inhalation by either consumers or factory workers. While MWCNT inhalation has been previously shown to cause inflammation and pulmonary fibrosis at high doses, the susceptibility of differentiating bronchial epithelia to MWCNT exposure remains unexplored. In this study, we investigate the effect of MWCNT exposure on cilia development in a differentiating air-liquid interface (ALI) model. Primary bronchial epithelial cells (BECs) were isolated from human donors via bronchoscopy and treated with non-cytotoxic doses of MWCNTs in submerged culture for 24 h. Cultures were then allowed to differentiate in ALI for 28 days in the absence of further MWCNT exposure. At 28 days, mucociliary differentiation endpoints were assessed, including whole-mount immunofluorescent staining, histological, immunohistochemical and ultrastructural analysis, gene expression, and cilia beating analysis.ResultsWe found a reduction in the prevalence and beating of ciliated cells in MWCNT-treated cultures, which appeared to be caused by a disruption of cellular microtubules and cytoskeleton during ciliogenesis and basal body docking. Expression of gene markers of mucociliary differentiation, such as FOXJ1 and MUC5AC/B, were not affected by treatment. Colocalization of basal body marker CEP164 with γ-tubulin during days 1–3 of ciliogenesis, as well as abundance of basal bodies up to day 14, were attenuated by treatment with MWCNTs.ConclusionsOur results suggest that a single exposure of bronchial cells to MWCNT during a vulnerable period before differentiation may impair their ability to develop into fully functional ciliated cells.

Simple and green fabrication of recyclable magnetic highly hydrophobic sorbents derived from waste orange peels for removal of oil and organic solvents from water surface

This study presents the preparation and characterization of natural waste material (orange peel) derived low cost, bio-based, recyclable, highly hydrophobic/superoleophilic magnetic sorbents to treat environmental pollution caused by oils and organic contaminants from water. Orange peels were dried, powdered and converted into magnetic and highly hydrophobic/superoleophilic sorbents by the incorporation of Fe3O4 nanoparticles using co-precipitation approach and subsequently modifying with low surface energy polydimethylsiloxane (non-fluorinated hydrophobic reagent) layers. SEM, EDS, XRD, FTIR, XPS, TGA, VSM and contact angle measurements analysis were used for characterization of the developed materials. The as-prepared sorbents exhibit strong magnetic behavior with saturation magnetization (Ms) value of 14.9 emu/g, excellent hydrophobicity with water contact angle of 149.2° and very high capacity for the selective absorption of various oils and organic solvents from oil contaminated water. It has high absorption capacity up to 5.11 and 6.90 times its original weight for diesel oil and engine oil respectively, along with high recyclability of more than eight cycles and the advantage of magnetic separation from water surface after absorption of oils. Thus, the orange peel waste derived absorbent with magnetic and high hydrophobic properties is a promising alternative for the capture of oil and organic pollutants from water.

Graphene aerogel prepared through double hydrothermal reduction as high-performance oil adsorbent

Cork-like graphene aerogels were synthesized via EDA-ammonia double hydrothermal reduction approach. The synthesized porous aerogels displayed high porosity, hydrophobicity and excellent mechanical properties. Its adsorption efficiency for oil is significantly higher than that of conventional adsorbents, having oil capacity (130.10g/g) for pure diesel and continuous treatment capacity (71.67g/g) for emulsified oil in oil-contaminated water. Besides, its recycling performance was evaluated by mechanical extrusion, ethanol washing and calcined regeneration, and for emulsified oil, the adsorption process follows a pseudo-second-order kinetic model and adsorption isotherms are related well by the Freundlich model with a determination coefficient. (R2) of 0.9994. Furthermore, a continuous aerogel-based water treatment process has been proposed to make the graphene-based aerogels have great potential applications for oil spill clean-up and water purification.

Silicone rubber with mussel-inspired adhesive coatings for enhancing antifouling property and blood compatibility

Silicone rubber is widely used in various biomedical fields. However, the silicone surface is known to cause biofouling and thrombosis issues due to its higher hydrophobic property. In this study, to improve its antifouling property and blood compatibility, silicone rubber was modified by coating of hyaluronic acid (HA) or poly(ethylene glycol) (PEG). To enhance adhesive property of HA and PEG on the silicone surface, HA and PEG were modified by introducing the amino groups of dopamine (DA) to the carboxyl group of each polymer. The modified HA (HA-DA) and PEG (PEG-DA) were confirmed by 1H nuclear magnetic resonance (NMR) and the coated surfaces were characterized with contact angle, X-ray photoelectron spectroscopy (XPS), and micro-bicinchoninic acid (micro-BCA) analyses. To compare antifouling property and blood compatibility, adsorbed proteins, adhered platelets, and anticoagulation on the modified surfaces were evaluated by fluorescence microscopy, scanning electron microscopy, and activated partial thromboplastin time (APTT) assay, respectively. The property of cell adhesion on the modified surface was evaluated by NIH 3T3 fibroblast as a model cell system. Protein, platelet, and fibroblast showed low adsorption and adhesion on the modified silicone rubber surfaces compared to the unmodified one. Especially, the third coated silicone rubber surfaces were found to strongly resist protein adsorption as well as platelet and fibroblast adhesion. These results indicated that the antifouling property and blood compatibility were enhanced significantly on HA-DA and PEG-DA immobilized silicone rubbers. Therefore, these modified silicone rubbers can be used in various biomedical applications.

Nanoparticles Covered Surfaces for Post-functionalization with Aromatic Groups to Obtain Parahydrophobic Surface with High Water Adhesion (Petal Effect)

Numerous exceptional properties can be observed in nature. Among these properties, parahydrophobic feature is of interest. This property describes material with high adhesion with water such as rose petals or gecko foot. Such kind of surface presents a real potential for applications in the field of water harvesting systems. In this work, we report a new synthetic strategy to mimic this property. Here, we combine three strategies in one. First, a monomer is electropolymerized in order to form the starting structured surface. Then, nanoparticles are grafted on the surface to increase the structuration and consequently to create the reactive surface. Finally, the grafted surface is post-functionalized (Huisgen reaction) with various aryl alkynes to control the surface chemistry and energy. This strategy allows to reach surfaces with both very high hydrophobic properties (θ = 140°) and high water adhesion. This work also includes the surface wettability, roughness and morphology investigation in order to study the impact of the starting monomer structure and post-functionalization on the surface properties.

Physicochemical Nature of Perfluoroalkyl Compounds Induced by Fluorine.

Perfluoroalkyl (Rf ) compounds have unique characters represented by a significantly high hydrophobic property, which often makes us consider that Rf groups should be interacted with each other via the 'hydrophobic interaction' as found for a normal hydrocarbon. Due to a similar intuitive and simplistic speculation, the Rf -specific material properties have long been enveloped in darkness for comprehensive understanding, which should lucidly be discussed within a framework of physical chemistry. Here, we show studies on the stratified dipole arrays (SDA) theory, which readily explains the Rf -specific material characters in a comprehensive manner based on only a few fundamental physical parameters of fluorine. The SDA theory encompasses some conventional theories that account for only a part of material properties. In addition, we show that the concept of vibrational spectroscopy of Rf compounds should also be revised, since the mass of fluorine is larger than that of carbon, which is opposite to the hydrocarbon case. In this manner, chemistry of Rf compounds needs another fully revised concept, which cannot be replaced by an extended concept of normal hydrocarbon compounds.

Modification of fumed silica surface with mixtures of polyorganosiloxanes and dialkyl carbonates

Abstract In the present investigation, firstly, the surface of silica (SiO 2 ) nanoparticles was modified with polyorganosiloxanes with different length of the polymer chain in the presence of dialkyl carbonates as initiators of siloxane bond splitting. The resulting nanocomposites were fully characterized by various techniques such as infrared spectroscopy, elemental analysis, microcalorimetric and contact angles of wetting measurements, transmission electron microscopy (TEM) and rotational viscosity. The IR spectroscopy and elemental analysis data showed an increase of carbon content in the grafted layer of modified silicas and full participation of free silanol groups in chemisorption processes at the relatively moderate temperatures (220 °C). Microcalorimetric and contact angles studies confirmed high hydrophobic surface properties of the obtained materials. The coatings microstructure of nanocomposites was characterized by TEM analysis. It was shown that the obtained hydrophobic products are characterized by high uniformity of nanoparticles. The rheology results indicated that modified fumed silica forms stable suspensions with thixotropic behavior.

In Vitro Activity of Lactobacilli with Probiotic Potential Isolated from Cocoa Fermentation against Gardnerella vaginalis.

Study of the probiotic potential of microorganisms isolated from fermented foods has been increasing, especially studies related to lactobacilli. In intestinal models, lactobacilli have demonstrated beneficial properties, such as anti-inflammatory activity and increased antibody production, but the molecular mechanisms involving probiotic and antagonistic action as well as their effect on human vaginal cells have not yet been fully elucidated. The aim of this study was to evaluate the functional and antagonistic properties of three strains of lactobacilli isolated from cocoa fermentation (Lactobacillus fermentum 5.2, L. plantarum 6.2, and L. plantarum 7.1) against Gardnerella vaginalis. Our results show that the lactobacilli have potential use as probiotics, since they have high hydrophobicity and autoaggregation properties and effectively adhere to vaginal cells. Metabolites secreted into the culture medium and whole cells of the strains under study are capable of interfering with the growth of G. vaginalis to different degrees. The elucidation of the antagonistic mechanisms as well as their effect on human cells may be useful in the development of a product containing such microorganisms or products secreted by them.

Preparation and characterization of highly hydrophobic magnetic polyaniline nanocomposite for fast and efficient separation of diesel oil from seawater

In this work, hydrophobic magnetic polyaniline nanocomposite (PAni/Fe3O4/C) was prepared by insitu emulsion polymerization of aniline in the presence of magnetic carbon. Magnetic nanocomposites were characterized by FT-IR spectra, X- ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). Brunauer-Emmett-Teller (BET) method was utilized to measure specific surface area and pore size distribution of magnetic nanocomposites. The water contact angle values for both magnetic nanocomposites indicated high hydrophobic properties for PAni/Fe3O4/C. PAni/Fe3O4/C was evaluated for removal of diesel oil from seawater by magnetic separation. Separation capacity (g/g) was governed by separation time, magnetic nanocomposite dose as well as initial oil concentration. Kinetic studies showed that oil separation process followed pseudo-second-order model. Thermodynamics studies of oil sorption process were investigated at temperature range (283K–323K) and indicated endothermic, spontaneous and random behavior. The reusability of magnetic polyaniline sorbent was carried out for ten cycles.

Fabrication of TiO2/PU Superhydrophobic Film by Nanoparticle Assisted Cast Micromolding Process.

Lotus-like surfaces have attracted great attentions in recent years for their wide applications in water repellency, anti-fog and self-cleaning. This paper introduced a novel process, nanoparticle assisted cast micromolding, to create polymer film with superhydrophobic surface. Briefly, waterborne polyurethane (WPU) sol and nano TiO2/WPU sol were each cast onto the featured surfaces of the poly(dimethylsiloxane) (PDMS) stamps replicated from fresh lotus leaves. After being dried and peeled off from the stamps, PU and TiO2/WPU replica films were created respectively. To the former, only high hydrophobic property was observed with static water contact angle (WCA) at 142.5 degrees. While to the later, superhydrophobic property was obtained with WCA more than 150 degrees and slide angle less than 3 degrees. Scanning electron microscopy (SEM) imaging showed that the PU replica film only had the micro-papillas and the TiO2/PU replica film not only had micro papillas but also had a large number of nano structures distributed on and between the micro-papillas. Such nano and micro hierarchical structures were very similar with those on the natural lotus leaf surface, thus was the main reason for causing superhydrophobic property. Although an elastic PDMS stamp from lotus leaf was used in herein process, hard molds may also be used in theory. This study supplied an alternative technique for large scale production of polymeric films with superhydrophobic.