Wettability Of Films Research Articles

Effects of Argon Partial Pressure Variations on Wettability and Anti-icing Characteristics of Aluminum Doped ZnO Thin Films

When ice forms on solid surfaces, it can cause issues in many different sectors (aircraft, electricity lines, etc.). Surfaces and coatings with hydrophobic qualities may be used in anti-icing applications. The purpose of this work is to utilize RF Magneton Sputtering to deposit AZO thin coatings, which will slow the accumulation of ice on the surface. The effects of changes in argon partial pressure on the anti-icing, wettability, optical, and structural properties of the resulting thin films have been experimentally investigated. X-ray diffraction demonstrated a (002) peak of ZnO, the intensity of the peak diminishes with an increase in partial pressure. The band gap was measured to be between 2.98 and 3.15 eV, and the average maximum transmittance was observed to be around 82% for 50% partial pressure and 71% for 33% partial pressure, confirming the transparency of the thin films. Wettability studies revealed that the films are hydrophobic with a maximum contact angle of 127.5°, which was deposited at lower partial pressure. Films deposited at 33% partial pressure delayed the formation of ice on the surface by 4.5 folds when compared to an uncoated substrate.

Preparation of poly (lactic-co-glycolic acid) microfiber membrane

Poly (lactic-co-glycolic acid) (PLGA) is a kind of medical polymer material with good biodegradability and histocompatibility, which is widely used in postoperative anti-adhesion materials. In this paper, PLGA microfiber membrane was successfully prepared with poly(lactic-co-glycolic acid) as the main material by electrospinning technology. The surface morphology, wettability, dimensional stability and mechanical properties of PLGA microfiber films were characterized by scanning electron microscopy (SEM) and tensile testing machine. The results show that the average diameter of the prepared PLGA fiber is 2.218~2.313 μm, the elongation at break of the fiber film is up to 193%, and the dimensional stability and wettability of the fiber film are maintained at 37°C. The degradation cycle is 2~3 months.

Effect of molar mass and alkyl chain length on the surface properties and biocompatibility of poly(alkylene terephthalate)s for potential cardiovascular applications.

Cardiovascular diseases are the leading cause of death worldwide. Treatments for occluded arteries include balloon angioplasty with or without stenting and bypass grafting surgery. Poly(ethylene terephthalate) is frequently used as a vascular graft material, but its high stiffness leads to compliance mismatch with the human blood vessels, resulting in altered hemodynamics, thrombus formation and graft failure. Poly(alkylene terephthalate)s (PATs) with longer alkyl chain lengths hold great potential for improving the compliance. In this work, the effect of the polymer molar mass and the alkyl chain length on the surface roughness and wettability of spin-coated PAT films was investigated, as well as the endothelial cell adhesion and proliferation on these samples. We found that surface roughness generally increases with increasing molar mass and alkyl chain length, while no trend for the wettability could be observed. All investigated PATs are non-cytotoxic and support endothelial cell adhesion and growth. For some PATs, the endothelial cells even reorganized into a tubular-like structure, suggesting angiogenic maturation. In conclusion, this research demonstrates the biocompatibility of PATs and their potential to be applied as materials serving cardiovascular applications.

Influence of TiO2 thin film on critical heat flux and performance enhancement of pool boiling at atmospheric pressure

An increase in the rate of heat generation due to the compactness and performance enhancement of electronics equipment has been observed in the recent years. Though the efficient heat recovery to improve safety and to increase the life span of the equipment is a challenging task, Pool boiling is considered as a technique to recover an abundant quantity of heat at minimum wall superheat. The performance and safety factors are explored using boiling heat transfer coefficient and critical heat flux. The present investigation is carried out on a plain copper surface and copper surface coated with TiO2 thin film with three different thicknesses, namely 250, 500 and 750 nm. This work also explores the influence of wettability and roughness of the TiO2 thin film coated surfaces. The morphological and structural studies are conducted by scanning electron microscopy and x-ray diffraction scanning electron microscopic patterns. The critical heat flux of TiO2 thin film coated surface at 750 nm thicknesses was better augmented by 69% than the plain copper surface. The heat transfer coefficient was better augmented by 117% than the uncoated copper surface. The excellence in hydrophillic nature of the TiO2 thin film creates numerous nucleation sites which in turn enhance the capillary wicking. The continuous wetting and rewetting characteristics of the TiO2 thin film enhance the critical heat flux and boiling heat transfer coefficient.

Selenium-decorated biocompatible honeycomb films with redox-switchable surface for controlling cell adhesion/detachment

Hypothesis.Selenium (Se)-containing compound is sensitive to redox stimulation, showing hydrophobic-hydrophilic reversible transition. Introduction of such compound into honeycomb film could confer on it redox-switchable surface wettability, which is expected to control cell adhesion/detachment behavior.Experiments.Didodecyl selenide was designed and mixed with polystyrene to prepare honeycomb films using “breath figure” method. The film microstructures were characterized by scanning electron microscope and atomic force microscopy, and the arrangement of Se atoms in honeycomb film was determined by X-ray photoelectron spectroscopy and energy dispersive spectrometry. The variation of film wettability upon the alternating stimulation of H2O2 and Vc was examined. Then the cell adhesion, proliferation, and controlled detachment on honeycomb films were conducted.Findings.The introduction of didodecyl selenide helps to form ordered honeycomb film, and Se atoms were found to located on the bottom, pore walls, and top surface of the film. The presence of didodecyl selenide not only greatly improves film biocompatibility by enhancing cell thioredoxin reductase activity, but also imparts the film with H2O2–/vitamin C-regulated tunable wettability that controls cell adhesion and detachment. H2O2 treatment produces a hydrophilic surface for cell adhesion and proliferation, whereas the addition of vitamin C generates hydrophobic surfaces and allows cells to detach while remaining alive with high activity.

Effects of Zn injection on corrosion behavior and crud deposition of FeCrAl fuel cladding under subcooled nuclear boiling condition in high-temperature pressurized water

The effects of Zn injection on corrosion behavior and crud deposition of FeCrAl fuel cladding in high-temperature pressurized water were investigated under subcooled nuclear boiling condition. The crud deposition and the growth of double-layered oxide films under the crud occurred simultaneously. Zn injection decreased the oxide films thickness and reduced the quantity/size of the outer oxide particles. These effects changed the surface roughness and wettability of the oxide films, resulting in a reduction of deposited crud at the initial stage. Both Zn and released matrix elements could be incorporated into the crud and Zn reduced the size of crud particles.

Changes in cell surface properties of Pseudomonas fluorescens by adaptation to NaCl induced hypertonic stress.

Determination of the effect of water stress on the surface properties of bacteria is crucial to study bacterial induced soil water repellency. Changes in the environmental conditions may affect several properties of bacteria such as the cell hydrophobicity and morphology. Here, we study the influence of adaptation to hypertonic stress on cell wettability, shape, adhesion, and surface chemical composition of Pseudomonas fluorescens. From this we aim to discover possible relations between the changes in wettability of bacterial films studied by contact angle and single cells studied by atomic and chemical force microscopy (AFM, CFM), which is still lacking. We show that by stress the adhesion forces of the cell surfaces towards hydrophobic functionalized probes increase while they decrease towards hydrophilic functionalized tips. This is consistent with the contact angle results. Further, cell size shrunk and protein content increased upon stress. The results suggest two possible mechanisms: Cell shrinkage is accompanied by the release of outer membrane vesicles by which the protein to lipid ratio increases. The higher protein content increases the rigidity and the number of hydrophobic nano-domains per surface area.

Current Understanding of the Wettability of MXenes

AbstractSince the first report regarding the successful fabrication of few‐layer transition metal carbides (known as MXenes) of 2011, their intrinsic properties, such as mechanical strength and electrical conductivity, are intensively studied. Though the hydrophilic nature of MXenes is widely reported and utilized to fabricate various functional materials, there is a lack of systematic study with respect to the science behind the wetting phenomena of MXene‐based materials. The goal of this manuscript is to provide some useful guidelines in the design of novel MXene‐based systems with desirable wetting properties by analyzing the current understanding of the wettability of MXenes. Specifically, after the introduction of the fundamental concepts in wetting theory, the wettability of pure MXene films is summarized based on the recently published results from both theoretical and experimental studies. Then, the determining factors in the wetting properties of MXenes associated with surface architectures and chemical compositions are clarified, which is followed by the effect of hybridization strategies discussed in detail. In the end, a summary of the abundant applications relying on the wetting properties of MXene‐based systems is presented along with the current challenges and the corresponding future research directions in this field.

Microstructure and properties of Mo doped DLC nanocomposite films deposited by a hybrid sputtering system

A combination of low internal stress and hydrophobic performance for carbon film is crucial in some practical applications. In this work, Mo doped diamond-like carbon (DLC) films were deposited by a hybrid coating system. The designed DLC films with various Mo contents were obtained by adjusting the Mo target powers. The microstructure and comprehensive properties including wettability of Mo-DLC films were analyzed systematically. Results showed that with increasing the Mo target power, Mo content and deposition rate of films were continuously increased, and also the surface roughness slightly increased. At low Mo doping, films mainly exhibited amorphous feature, whereas, the MoC nanocrystallites were found at high Mo doping, implying the nanocomposite structure formed where MoC crystals were embedded in the carbon matrix. The sp3-C bond fraction was decreasing with increasing the Mo content due to the metal catalyst effect, which effectively promoted the sp3-C bonds transforming into sp2-C bonds. Meanwhile, the Mo addition had a significant positive effect on the reduction of residual stress. Moreover, the wettability of films was transferred from hydrophilicity state to hydrophobicity state, and the maximum water contact angle was 94.2° at 20.1 at. % Mo doping, then slightly diminished to 92.7° with further increasing Mo content. The present work would offer an available method to fabricate the DLC film with low internal stress and desirable wettability property.

Investigation of Wettability and AC-Conductivity of EVA/PANI Composite

In the current work, EVA/PANI composite is successfully prepared by in-situ technique. Both prepared materials are characterized by XRD, FTIR, UV-Visible, and SEM analyses. Wettability and dielectric properties of both EVA film and EVA/PANI composite are studied. High intense peak is found in EVA/PANI composite and is indicated more crystalline nature compared to pristine EVA polymer film. π-π* and polaron transitions are appeared in the UV-Visible spectrum of EVA/PANI composite. Different absorption band of EVA film and EVA/PANI composite are viewed in their spectrum. A study has been made of wettability of smooth surfaces of EVA and HCl doped EVA/PANI materials by observing the equilibrium contact angle formed by a liquid drop resting on the solid surface. Wettability results of EVA/PANI composite shows hydrophilic nature. Frequency dependent AC electrical conductivity and Dielectric are analyzed for both materials.

Surface Modification of a Regenerated Cellulose Film Using Low-Pressure Plasma Treatment with Various Reactive Gases.

There is a growing interest in the fabrication of membranes and packaging materials from natural resources for a sustainable society. A regenerated cellulose (RC) film composed solely of cellulose has outstanding advantages including biodegradability, transparency, mechanical strength, and thermal stability. To expand the application of the RC film, various surface modification methods have been proposed. However, conventional chemical methods have disadvantages such as environmental burden and difficulty in controlling the reaction. In this work, low-pressure plasma treatment, a green, solvent-free, and easily controllable approach, was performed for surface modification of the RC film. The effects of three different plasma species (O2, N2, and CF4) and treatment conditions on the surface properties of RC films were investigated based on water contact angle measurements, chemical composition analysis, and surface topography. O2 and N2 plasma treatment slightly enhanced the surface wettability of RC films due to the etching by the plasma reactive species and the formation of new hydrophilic functional groups. In CF4 plasma treatments, the hydrophobic surface with a contact angle of 120.6° was obtained in a short treatment time (60 s) owing to the deposition of fluorocarbon groups on the surface. However, the treated surface in a longer reaction time resulted in increased wettability due to the diffusion and degradation of fluorine-containing bonds. The new insights could be valuable for further studies of surface modification and functionalization of RC films.

Determination of rational steam consumption in steam-air mixture flotation of apatite-nepheline ores

Relevance of the study is determined by the decisions taken to increase the production volume of certain commercial products from mineral raw materials. The scale, impact and consequences of the projects on developing the resource-saving technologies for beneficiation of mineral raw materials are socially significant, and the economic growth of mining production complies with the sustainable development goals. The aim of the study is to develop the flotation circuit and mode that improve the technological performance of beneficiation of apatite-nepheline ores of the Khibiny Massif in the Kola Peninsula. The scientific idea of ​​the work is to develop the flotation circuit, the movement of beneficiation products in which ensures a major increase in the content of the recovered component in the rougher flotation procedure with a simultaneous increase in dressability of the material. The above condition is met when mixing the feedstock with rough concentrate. Recovery of the valuable component from the resulting mixture is accomplished in a mode differing from the known ones in that the heat of steam condensation is used to increase water temperature in the interphase film between the particle and the bubble. For pulp aeration during flotation, a mixture of air and hot steam is used as the gas phase. A high recovery of the valuable component in ore flotation according to the developed circuit and mode is facilitated by increasing water temperature in wetting films due to the steam condensation heat. A high selectivity of flotation with a steam-air mixture can be explained using the concepts of a phonon component of disjoining pressure, the value and sign of which are associated with a difference in the dynamic structure of liquid in the wetting film and bulk liquid.

Microstructures, mechanical properties and surface wettability of La-doped diamond-like carbon films deposited by magnetron co-sputtering

In this study, La-doped diamond-like carbon (DLC) films were prepared by magnetron co-sputtering of individual graphite and La targets. The mechanical properties and surface wettability of the DLC films were investigated in terms of the evolutions of microstructures and chemical compositions with La content. The results revealed that the doped La dissolved into the DLC films working as a catalyst made them smoother and locally graphitized. Moreover, a different dependency of residual stress upon sp3-C fraction to that of hardness and elastic modulus was found in the DLC films. Further, the air-exposed DLC films suffered from a series of surface physical/chemical reactions with air molecules and ubiquitous volatile organic compounds (VOCs), accompanied by brilliant and quick color evolutions over initial time, which dominated the time-dependent surface wettability. Finally, the doping-induced enhancements of both VOCs adsorption and sp2-C fraction contributed to the surface wettability transition from the intrinsic hydrophilicity to desired hydrophobicity of the DLC film. This study demonstrated here aims to expose the complex microstructures and related properties of DLC films with La doping, and offer a feasible method of preparing high-performance DLC films with low residual stress and adjustable surface wettability.

A novel material based on an antibacterial choline-calixarene nanoassembly embedded in thin films

Supramolecular chemistry is one of the current strategies for producing advanced materials. With the aim to develop new Thin-Films with antibacterial activity, we embedded an amphiphilic choline-calix[4]arene possessing antibacterial properties in polymeric Thin-Films based on polyether-co-amide matrix (Pebax®2533). The loading of the calix[4]arene derivative in the film was performed by solution casting. The amount of calixarene additive in the films was in the range of 0.5–5 wt%. The self-supported Thin-Films were characterized by investigating phase miscibility, morphology, spectral properties, and gas transport. The release of the calixarene derivative from the films was studied in a biomimetic medium as PBS (10 mM, pH 7.4). The presence of the additive did not affect the thermal stability of the copolymer, whereas it induced an increase in crystallinity, wettability, and gas permeability of the blend films according to its concentration. The antibacterial activity of the films was evaluated in vitro against Escherichia coli and Staphylococcus aureus strains, representative of Gram-negative and Gram-positive bacteria. The developed films displayed antibacterial activity against both strains. In particular, Pebax® − 5 wt% Chol-Calix caused within 10 h a reduction in E. coli and S. aureus of 2.57 and 2 log CFU/mL, respectively. The potential toxicity of the films was also tested on mouse embryonic fibroblasts NIH/3T3. Pebax®2533/calixarene derivative combination appears a promising approach for the development of novel flexible antibacterial materials.Graphical abstract

Hydrogen‐bonded polymer multilayer coatings via dynamic layer‐by‐layer assembly

AbstractWe developed the dynamic assembly of the hydrogen‐bonded multilayers of (poly(N‐vinylpyrrolidone/poly(methacrylic acid)) (PVPON/PMAA)) and compared their properties to the static multilayers. We found that dynamic multilayers, wherein a planar substrate is shaken during polymer adsorption, leads to a 15‐time faster deposition of the planar coatings. The thicknesses and roughness of the dynamic coatings were found to be ⁓30% larger than those of static (no shaking) multilayer films as measured by spectroscopic ellipsometry and atomic force microscopy. We examined the film growth, mechanical properties, wettability, hydration, and pH stability of the planar static and dynamic multilayers and demonstrated that these properties were insignificantly affected by the assembly mode. Both static and dynamic coatings produced microporous films when exposed to pH = 5.9, close to the film critical dissolution pH = 6. We discovered that during the release of the multilayer films into a solution to produce free‐standing films either as planar membranes or multilayer capsule shells, the molecular chain rearrangements result in the decreased roughness for both static and dynamic multilayers and lead to a decreased thickness of the dynamic multilayers. Our findings can help develop a rapid synthesis of thicker nanostructured polymer coatings for sensing and controlled delivery applications.

Tissue Engineering Scaffold Material with Enhanced Cell Adhesion and Angiogenesis from Soy Protein Isolate Loaded with Bio Modulated Micro-TiO2 Prepared via Prolonged Sonication for Wound Healing Applications.

Tissue engineering is a technique that promotes healing by creating an ideal environment for endogenous cells to migrate and grow into the site of injury via a scaffold, improving regeneration and reducing the time required for in vitro cell culture. In this work, the effect of the addition of sonicated TiO2 in the soy protein isolate (SPI) matrix for tissue engineering applications was studied. In comparison to adding expensive nano TiO2, this method of incorporating sonicated TiO2 into the SPI matrix will aid in achieving improved properties at a lower cost. The effect of the addition of sonicated TiO2 on the morphological, UV transmittance, mechanical, thermal, surface energy, and hydrophilicity of SPI films was investigated. The result shows that the uniformly distributed TiO2 particles successfully blocked 95% of UV light. Scanning electron microscopy revealed a significant reduction in the TiO2 agglomerate size and homogeneous distribution of the same when sonication was applied instead of mechanical dispersion. A simultaneous increase of tensile strength (from 3.16 to 4.58 MPa) and elongation at break values (from 24.25% to 95.31%) with 0.5% TiO2 was observed. The addition of 0.25% TiO2 was found to significantly enhance the elongation at break value to 120.83%. Incorporation of micro-TiO2 particles could improve the surface roughness, surface energy, and wettability of SPI films. In vitro cell adhesion studies and in vivo subcutaneous implantation studies were performed to assess the cell growth and angiogenesis of the developed film membranes. An MTT assay showed that SPI-1%TiO2 film favored cell viability up to 118%, and in vivo subcutaneous implantation studies showed enhanced cell growth and angiogenesis for SPI-1% TiO2 films. This SPI-TiO2 film with enhanced surface properties can be used as an ideal candidate for tissue engineering applications.

Wetting Ridge-Guided Directional Water Self-Transport.

Directional water self-transport plays a crucial role in diverse applications such as biosensing and water harvesting. Despite extensive progress, current strategies for directional water self-transport are restricted to a short self-driving distance, single function, and complicated fabrication methods. Here, a lubricant-infused heterogeneous superwettability surface (LIHSS) for directional water self-transport is proposed on polyimide (PI) film through femtosecond laser direct writing and lubricant infusion. By tuning the parameters of the femtosecond laser, the wettability of PI film can be transformed into superhydrophobic or superhydrophilic. After trapping water droplets on the superhydrophilic surface and depositing excess lubricant, the asymmetrical wetting ridge drives water droplets by an attractive capillary force on the LIHSS. Notably, the maximum droplet self-driving distance can approach ≈3mm, which is nearly twice as long as the previously reported strategies for direction water self-transport. Significantly, it is demonstrated that this strategy makes it possible to achieve water self-transport, anti-gravity pumping, and chemical microreaction on a tilted LIHSS. This work provides an efficient method to fabricate a promising platform for realizing directional water self-transport.

In Situ Shale Wettability Regulation Using Sophisticated Nanoemulsion to Maintain Wellbore Stability in Deep Well Drilling.

Wettability alteration of the shale surface is a potential strategy to address wellbore instability issues arising from shale hydration. In this study, we have explored an oil-in-water (o/w) nanoemulsion, in which soluble silicate (lithium silicate and potassium methyl silicate) as the aqueous phase and organosilanes (3-methacryloxypropyltrimethoxysilane (KH570) and n-octyltriethoxysilane (n-OTES)) as the oil phase, as a shale inhibitor via forming a hydrophobic "artificial borehole shield" in situ on shale surfaces to maintain wellbore stability in high-temperature drilling operations. The shale dispersion test showed the highest shale recovery of nanoemulsion was up to 106.4% compared to that of water (20%), and recovered shale cuttings remained at the original integrity after hot rolling at 180 °C, indicating superior inhibition performance and resistance to elevated temperatures. Moreover, recovered shale cuttings manifested water repellency upon reimmersion in water, ascribed to the hydrophobic film, preventing water from permeating into the shale. The results of the contact angle measurement elucidated that the film wettability, from hydrophilic to superhydrophobic (ranging from 9.6-154°), can be achieved by altering the n-OTES-to-KH570 weight ratio from 0.2 to 2.25, and the film with the highest hydrophobicity (154°) and the lowest surface energy (3.17 mJ·m-2) can be obtained at a ratio of 1.3. Scanning electron microscopy images demonstrated that the superhydrophobic film was composed of tightly stacked reticulate nanofilaments with a diameter of 7-17 nm and several micrometers in length and overlapped well-distributed nanospheres with a diameter of 30 nm. X-ray diffraction and Fourier transform infrared spectroscopy confirmed the film was crystalline silica grafted with long-chain alkylsiloxane. It is assumed that the unique micronanostructure combined with the siloxane modification contributed to the hydrophobicity. Consequently, this study provides a potential alternative solution for wellbore stabilization in deep well drilling engineering by employing nanoemulsion as a shale hydration inhibitor via forming a protective film with controllable wettability. Furthermore, it can be conferred a practical application due to easily available, less hazardous, and cost-effective materials.

Comparison of the physicochemical properties and aging behavior of two different APTES-derived plasma polymer-based coatings

Recently, new plasma polymerization-based techniques emerged to deposit chemically functional coatings for various applications. However, little is known on the aging of these layers. Therefore, this study aims to investigate the physicochemical properties of aerosol-assisted atmospheric pressure plasma deposited (3-aminopropyl)triethoxysilane-based (AAPD-APTES) coatings and compare their aging behavior to APTES-modified plasma polymerized hexamethyldisiloxane-based coatings (ppHMDSO-APTES). X-ray photoelectron spectroscopy (XPS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), water contact angle (WCA) and atomic force microscopy (AFM) measurements indicated that the applied power had an insignificant impact on the wettability, chemistry and morphology of the AAPD-APTES films. A complex nitrogen-containing organosilicon layer was obtained with significant preservation of the Si-O-C-bonds. For the ppHMDSO-APTES coatings, XPS indicated that these layers had a significantly higher amount of preserved primary amines and a different surface morphology. Oxidation and hydrolysis of Si-O-C-bonds were the most prevalent aging processes for the AAPD-APTES coatings, while protonation of primary amines was most important for the ppHMDSO-APTES films. This study indicates that further research is needed to examine the differences in coating chemistry and aging of other AAPD-based and conventional plasma polymers. Additionally, it provides a reference to decide which coating type and associated aging processes are preferred for certain applications.

Effect of treatment time and radio frequency power on roughness and wettability of oxygen plasma-etched Cadmium Telluride thin films

The thermal evaporated Cadmium Telluride (CdTe) on Indium tin oxide substrates was etched using Oxygen plasma at various treatment times and radio frequency (RF) power. The roughness and wettability parameters were calculated using atomic force microscopy and contact angle (CA) analysis. The morphology evolution increases the interface width w and the lateral correlation length ξ with etching time and RF power. The local roughness exponent near-0.5 shows the self-affine of the surface during the etching process. The obtained experimental exponents in the present work introduce the universality class of the scaling exponents. The surface hydrophilicity of films was studied using the measurement of the two droplets CA on the film surface and the surface energy. The physical and chemical structure of the surface affected by oxygen plasma causes the surface to become more rough and hydroxyl group formation. Infra-Red spectra of the untreated and etched films using Fourier transform infrared spectroscopy confirmed the presence of the CdTe bond and a hydroxyl group. The wettability behavior of the etched films demonstrated the transition from the Cassie-Baxter state to the Wenzel state. Results show surface energy of the etched films increases, and theirs become hydrophilic.