Low Wettability Research Articles

Aging effect on surface chemistry and sorption properties of atmospheric pressure plasma treated lignocellulosic jute fibers

Jute fibers are characterized by a heterogeneous chemical composition (cellulose and non-cellulosic components) and a complex layered structure with a hydrophobic surface outer layer responsible for their low wettability. In this work, after the removal of water-soluble components, raw jute fibers were subjected to atmospheric pressure dielectric barrier discharge (DBD) under different conditions (at 150 or 300 Hz) to tailor jute fiber surface structure and wettability. The research was focused on the aging effect during natural aging in a standard atmosphere investigated up to three weeks after DBD treatment. Alterations in the surface morphology of DBD-treated jute fibers were investigated by FE-SEM and AFM, while ATR-FTIR, XPS, and electrokinetic measurements were used to assess the changes in the jute fiber surface chemistry. Sorption properties were monitored through wetting time and capillary rise measurements. The sorption properties of DBD-treated jute fibers were improved (about 100 times lower wetting time and 15 % higher capillary rise height in comparison to untreated) due to the changes in surface chemistry (decreased lignin and hemicellulose content in parallel with cellulose oxidation) and morphology (about 4.6 times higher average roughness). The electrokinetic and sorption properties measurement confirmed the significance of aging effects in lignocellulosic fibers' functionalization using plasma.

Enhancing Capacitance of Carbon Cloth Electrodes via Highly Conformal PEDOT Coating Fabricated by the OCVD Method Utilizing SbCl5 Oxidant

AbstractCarbon cloth shows potential for flexible energy storage electrodes but encounters challenges such as low specific capacitance and limited wettability. This study addresses these limitations by fabricating a highly conformal coating of poly(3,4‐ethylenedioxythiophene) (PEDOT) around 3D carbon fibers via the oxidative chemical vapor deposition (oCVD) method, employing antimony pentachloride (SbCl5) as the oxidant. The oCVD stands out as a robust manufacturing technique for fabricating highly conformal conducting polymer films on porous structures, ensuring the preservation of geometric features and the maintenance of active sites for redox reactions. The resulting PEDOT‐coated carbon cloth electrodes exhibit improved pseudocapacitance and specific capacitance compared to their pristine counterparts. Particularly, oCVD PEDOT‐coated carbon cloth fabricated at various deposition temperatures exhibit a substantial 1.5‐ to 2.3‐fold enhancement in specific capacitance compared to pristine carbon cloth. The highest specific capacitance (170.94 F g⁻¹) is attained in the oCVD PEDOT‐coated carbon cloth fabricated at a deposition temperature of 80 °C, representing a 2.3‐fold enhancement over its pristine counterpart. The PEDOT‐coated carbon cloths demonstrate lower charge transfer resistance compared to their pristine counterparts, further confirming their superior electrochemical performance. This investigation highlights oCVD's effectiveness in fabricating highly conformal PEDOT coating on carbon cloth electrodes for electrochemical energy storage devices.

Andiroba Oil (Carapa guianensis Aubletet) as a Functionalizing Agent for Titica Vine (Heteropsis flexuosa) Nanofibril Films: Biodegradable Products from Species Native to the Amazon Region

The diversity of species in Amazonia is exceptionally vast and unique, and it is of great interest for industry sectors to explore the potential of derivatives with functional properties for packaging applications. This study proposes the functionalization of cellulose micro/nanofibril (MFC/NFC) suspensions from Heteropsis flexuosa with andiroba oil to produce films with packaging potential. MFC/NFC was produced by using mechanical fibrillation from suspensions of H. flexuosa fibers. Proportions of 1, 3, and 5% of andiroba oil were added to make films with concentrations of 1% (m/m). Suspensions with andiroba oil provided greater viscosity, with changes in the physical properties of the films. Functionalization with andiroba oil provided films with lower degradation in water, greater contact angle, and lower wettability despite high permeability to water vapor. The films with 1% andiroba oil showed a hydrophobic characteristic (contact angle > 90°) and greater puncture resistance (6.70 N mm−1). Films with 3% oil showed a more transparent appearance and high biodegradation, while 1% oil generated more opaque films with a higher thermal degradation temperature and high antioxidant activity. It was concluded that films produced from H. flexuosa fibers functionalized with andiroba oil showed packaging potential for light, low-moisture products due to their adequate thermal and barrier characteristics.

Slate–Cork Laminate Enhanced with Silicone for Habitat Industry Application

This study investigates the feasibility of using a composite material comprising slate reinforced with cork sheets for architectural purposes like facades and wall coverings. The research involves the comprehensive characterisation of both slate and cork materials along with the evaluation of the silicone adhesive used in their bonding process, specifically Sikasil® HT from SIKA®. It was found that both slate and cork exhibited low wettability, which was enhanced through cold plasma treatment. Subsequently, a composite sandwich structure was fabricated and subjected to impact testing in a drop tower, along with fire resistance evaluations. The fire tests revealed that when subjected to a flame of 900 °C for 15 min, the slate alone heated rapidly, reaching 500 °C within 3 min on the side opposite to the flame. However, the sandwich structure reached 260 °C on the cork side (opposite to the flame) at 7.5 min, maintaining this temperature until the deterioration or detachment of the cork between 11 and 12 min. This provided insulation and delayed ignition. The sandwich structure maintained its fire resistance due to the insulating properties of cork and the superior thermal resistance of silicone compared to other adhesives up to 260 °C. Overall, the results suggest the potential suitability of this sandwich structure for architectural applications. Its favourable adhesion properties and acceptable fire resistance indicate that it could serve as a viable alternative for construction materials in architectural contexts.

Improving hydrophobicity of asphalt surfaces using pulverized recycled polyethylene terephthalate: Towards efficient roofing/waterproofing

Hydrophobic surfaces exhibit low wettability, low water and ice adhesion, etc. with an enhanced water resistance overall. Asphalt binder is popularly employed for roofing and waterproofing due to its intrinsic hydrophobicity. Yet, both unmodified and conventionally polymer-modified asphalt binders exhibit water contact angle (WCA) within the lower hydrophobic range (≤ 121°). Recent studies have shown that the hydrophobicity of asphalt binder can be enhanced via surface treatment using carefully selected materials. In this current study, the use of recycled polyethylene terephthalate (rPET) to improve the hydrophobicity of asphalt-binder was explored. The rPET was processed into micro-sizes and utilized to thermally treat the asphalt-binder at 100 °C. The morphology of the processed rPET and the treated-asphalt surfaces was examined using scanning electron microscopy (SEM). An optical surface profilometer was employed to quantify the roughness of the treated-asphalts. A video contact angle measurement system was used to measure the WCA of the unprocessed/untreated materials and the treated asphalt surfaces. The treated-asphalt showed average and maximum WCA of up to 144° and 148° respectively. This indicates that the rPET-treated asphalt surface could exhibit super-hydrophobicity (WCA ≥ 145°). The improvement in the WCA was due to the increase in surface roughness as a result of the embedment of rPET-particles onto the asphalt surface. The embedment resulted in the stretching of the asphalt surface, forming micro-valleys and -ridges of multiple hierarchies. Higher curing duration was found to yield treated-asphalts with hydrophobicity that last longer. It is found that micronized rPET with sizes smaller than 149 µm can be employed to successfully improve the hydrophobicity of asphalt binder surfaces.

Comprehensive Evaluation of Anti-icing Performance and Operational Efficiency of Superhydrophobic Propellers.

The icing of propellers is a critical factor that affects the safe operation of aircraft. A superhydrophobic surface, with its extremely low wettability, is highly valuable in the field of anti-icing. This study investigates the distribution pattern of ice on propeller surfaces by employing spray coating to create superhydrophobic surfaces. Additionally, it conducts a comparative analysis of thrust and power under icing and non-icing conditions to comprehensively assess the impact of superhydrophobic surfaces on propeller operation efficiency. The results show that superhydrophobic surfaces not only diminish the ice formation area on propeller surfaces but also enhance the traction of propellers under icing conditions, reducing the power consumption of the propeller. The generated thrust can reach up to 1.6 times that of non-superhydrophobic propellers while consuming only one-third of the power. Furthermore, under non-icing conditions, superhydrophobic surfaces exhibit minimal impact on propeller performance.

Mechanical Properties of Fe-TiC Composites for Friction Stir Welding Tool Application by a Spark Plasma Sintering

TiC, which has high hardness, was added to reinforcing material to improve the mechanical property of Fe. Fe-TiC composites as a function of TiC contents were fabricated by high energy ball milling and spark plasma sintering. The Fe-TiC composites were synthesized with different TiC contents (5, 10, and 20 wt.%) and subsequently consolidated by rapid sintering at 850℃ under 60 MPa. The relative density of Fe-TiC composites is from 99.5% to 94% as the TiC contents increased. Due to the increased in TiC contents, which contributes to the sintering rate with low wettability and low deformation at high temperature, has resulted in a decrease of relative density. The hardness of Fe-TiC was ranged from 128.9±10.4 to 687.2±14.6 kg/mm 2 as the TiC contents increased. Particularly, the highest hardness of TiC weight percent was 20 wt.% TiC which was related with Hall-Patch relationship. Also this enhancement was attributed to the dispersion strengthening effect of the agglomerated powders and solid solution strengthening through high energy ball milling. Microstructure, and phase analysis of Fe-TiC composites were investigated.

Effect of laser etching on surface characteristics and porcelain bond to soft milled and direct metal laser sintered cobalt chromium alloys

Statement of problemThe surface topography of metal substrate can affect its bond to porcelain. A neodynium-doped yttrium aluminum garnet (Nd:YAG) laser has been introduced to modify the metal surface topography and improve porcelain bond strength. However, studies on the effect of laser etching on metal to porcelain bond strength are lacking. PurposeThe purpose of this in vitro study was to determine the effect of Nd:YAG laser etching on the surface roughness and wettability of and the porcelain bond strength to cobalt chromium (Co-Cr) substrate fabricated by milling and direct metal laser sintering (DMLS). Material and methodsThirty-two 0.5×3×25-mm Co-Cr specimens were fabricated by milling soft Co-Cr (M group) and DMLS Co-Cr metal powder (DML group). The surface topography of representative specimens from each study group was assessed under a scanning electron microscope (SEM) and an atomic force microscope (AFM). All specimens were assessed for surface roughness using a contact profilometer, and for wettability with a contact angle goniometer. Half of the specimens of each study group (n=8) were subjected to surface laser etching by using a Nd:YAG laser. The specimens subjected to etching were assessed again for surface topography and wettability. All specimens in both study groups were veneered with porcelain. The porcelain bond strength was tested with a 3-point bend test in a universal testing machine. The results were statistically analyzed with 2-way ANOVA test followed by the post hoc Tukey test for pairwise comparisons (α=.05). ResultsAfter etching, the M group had a higher mean ±standard deviation Ra and Rz of 2.9 ±0.6 and 17.7 ±3.2 µm and significantly better wettability and bond strength of 79 ±6 and 52 ±13 MPa. In contrast, after etching, the DMLS group had a significantly lower Ra and Rz of 7.9 ±2.4 and 41.8 ±9.3 µm and significantly lower wettability and bond strength of 87 ±4 and 70 ±10 MPa. The DMLS group had a significantly higher roughness and bond strength than the M group before and after laser etching. The SEM and AFM showed different surface topography in the study groups. ConclusionsThe manufacturing process of Co-Cr substrate had a significant effect on surface characteristics and porcelain bond strength. Laser etching improved the surface topography and bond strength of milled Co-Cr but not of DMLS Co-Cr.

Elucidating the effects of surface wettability on boiling heat transfer using hydrophilic and hydrophobic surfaces with laser-etched microchannels

This study explores the nuanced interplay between surface wettability and morphology in nucleate boiling heat transfer. Surfaces with identical microstructures but varying wettability are created on copper substrates using laser texturing and a hydrophobic agent. The spacing between laser-etched microchannels is adjusted to achieve different contact angles and percentages of laser-textured areas. Boiling performance is assessed with variations in channel spacing and surface coverage, revealing significant differences between hydrophilic and hydrophobic surfaces. The critical heat flux (CHF) enhancement mechanisms are identified, emphasizing either enhanced liquid replenishment or separate boiling and liquid-supply regions. A critical laser line spacing of 100 μm is determined, where hydrophobic and hydrophilic variants exhibit similar CHF. Interestingly, hydrophilic surfaces show a weak correlation between the heat transfer coefficient (HTC) and contact angle, while hydrophobic surfaces demonstrate a strong correlation. This separation of surface morphology and wettability confirms that lower wettability promotes early nucleate boiling and high HTC, whereas hydrophilic variants contribute to enhanced CHF with lower HTC. These distinctions are most prominent at high coverage with laser-textured areas and diminish as coverage decreases. The findings provide valuable insights into optimizing surface properties for efficient boiling heat transfer applications.

Synthesis of biocomposites from microalgal peptide incorporated polycaprolactone/ κ- carrageenan nanofibers and their antibacterial and wound healing property

Antimicrobial peptides (AMPs) are promising novel agents for targeting a wide range of pathogens. In this study, microalgal peptides derived from native microalgae were incorporated into polycaprolactone (PCL) with ƙ-Carrageenan (ƙ-C) forming nanofibers using the electrospinning method. The peptides incorporated in the nanofibers were characterized by fourier infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy (SEM), and contact angle measurement. The results showed that peptides with molecular weights < 10 kDa, when loaded into nanofibers, exhibited lower wettability. The SEM analysis revealed a thin, smooth, interconnected bead-like structures. The antimicrobial activity of the electrospun nanofibers was evaluated through disc diffusion, and minimum inhibitory activity against Escherichia coli (MTTC 443), and Staphylococcus aureus (MTTC 96), resulting in zones of inhibition of 24 ± 0.5 mm and 14 ± 0.5 mm, respectively. The in vitro biocompatibility of the synthesized nanofibers was confirmed using in HEK 293 cell lines with an increased cell viability. Interestingly, the fibers also exhibited a significant wound-healing properties when used in vitro scratch assays. In conclusion, algal peptides incorporated with PCL/ ƙ-C were found to exhibit antimicrobial and biocompatible biomaterials for wound healing applications.

Temperature Effects on Physiochemical Characteristics of Sugar-Based Natural Deep Eutectic Solvents

Phase behavior, density, viscosity, conductivity, pH, and surface tension were measured, and FTIR was performed for a series of mixtures of sugar (glucose, fructose, xylose, and sucrose), water, and choline chloride (ChCl) at specific molar ratios. These mixtures, called sugar-based natural deep eutectic solvents (NADESs), were investigated as a function of temperature. Contact angle measurements indicated that NADES exhibited slightly lower wettability but higher surface tension than water. Temperature was found to greatly impact density, viscosity, and conductivity. The optimum water molar ratio for lower viscosity was found at ratios higher than those reported in the literature, indicating that the NADES investigated may have industrial process applications.

Vanadium Redox Flow Battery Using an N-Doped Porous Carbon-Coated Positive Electrode Derived from Zeolitic Imidazolate Framework-8-Coated Graphite Felt

The poor electrochemical activity and low wettability of graphite felt (GF) electrodes significantly limit the energy efficiency and power of vanadium redox flow batteries (VRFBs). To solve these problems, we developed an N-doped porous carbon-coated electrode by the carbonization of zeolitic imidazolate framework-8- (ZIF-8-) coated GF. By controlling the carbonization temperature, the effects of temperature on the structural morphology, pore structure, and amount and type of functional groups of the electrode were confirmed. In addition, the effect of the change in the pore structure and the amount and type of functional groups on the electrocatalytic activity for the vanadium redox reaction was demonstrated. The synthesized N-doped porous carbon-coated electrode, which showed the best electrochemical activity, had a sufficient amount of nitrogen functional groups with a high ratio of graphitic N and the highest surface area and pore volume among all the samples, providing abundant active sites for the VO2+/VO2+ redox reaction. The VRFB fabricated using prepared electrode exhibited energy and voltage efficiencies of 70.44% and 73.44%, respectively, at 200 mA cm-2, which were 11.77% and 11.08% higher than those of the bare GF electrode. Furthermore, the modified battery operated effectively at a high current density of 350 mA cm-2. The energy efficiency exhibited excellent stability over 500 charge/discharge cycles at 250 mA cm-2. Hence, this study presents a promising method for the development of high-performance VRFB electrodes.

A Novel Approach to Serving Plant-Based Confectionery—The Employment of Spray Drying in the Production of Carboxymethyl Cellulose-Based Delivery Systems Enriched with Teucrium montanum L. Extract

In this study, spray drying was used as a technological solution for the valorization of Teucrium montanum extract into carboxymethyl cellulose-based delivery systems (CMC), individually or in combination with collagen, guar gum, gum arabic, and kappa-carrageenan. The results showed that the process yield and morphological properties were positively influenced by the introduction of CMC binary blends. The employment of CMC resulted in a high encapsulation efficiency (77–96%) for all phenylethanoid glycosides (PGs) analyzed. Due to the low wettability of the microparticles, a relatively gradual in vitro release of the PGs was achieved. Infusion of the filling with hydrophilic T. montanum extract encapsulated in microparticles with high hydrophobic surface area proved to be a practical route for significant confectionery fortification (5–9 mg PGs per dw serving), ensuring prolonged interaction between the food matrix used and the extract under simulated gastrointestinal conditions. Based on sensory evaluation, the introduction of kudzu starch into the jelly matrix has shown a texture-modifying potential.

Rheological, Physicochemical, Thermal, and Mechanical Properties of Biopolymeric Films Incorporated with Micro‐Holocellulose from Coffee Residues

AbstractBiopolymeric materials have increased their uses and applications in the past years since more advanced preparations have been implemented to find the best formulation for a particular application. Holocellulose from spent coffee grounds (HOLO‐SCG) is a unique material with scarcely studied peculiarities. A detailed study of the flow behavior, microscopy, thermal, and local mechanical properties needs to be performed on biopolymeric films to open the understanding of polymer responsiveness, which is essential for the final design of the composites when fitting characteristics on macroscopic and microscopic scales are achieved. This manuscript aims to obtain biopolymer blends and films based on chitosan (CS) and polyvinyl alcohol (PVA) and reinforced with micro HOLO‐SCG. It seeks to investigate their compatibility and physicochemical properties in liquid states by rheological measurements and solid states using physicochemical, thermal, and mechanical experiments. The results indicate that the prepared CS : PVA films reinforced with HOLO‐SCG under controlled size provide an excellent biopolymeric structure with enhanced thermal and mechanical properties, which brings a stable product to be used as an alternative plastic due to their noticeable lower wettability. The biopolymeric film could be introduced as a bio‐composite material in food packaging applications in further experiments.

Sustainable food packaging: Harnessing biowaste of Terminalia catappa L. for chitosan-based biodegradable active films for shrimp storage

Shrimp, a globally consumed perishable food, faces rapid deterioration during storage and marketing, causing nutritional and economic losses. With a rising environmental consciousness regarding conventional plastic packaging, consumers seek sustainable options. Utilizing natural waste resources for packaging films strengthens the food industry. In this context, we aim to create chitosan-based active films by incorporating Terminalia catappa L. leaves extract (TCE) to enhance barrier properties and extend shrimp shelf life under refrigeration. Incorporation of TCE improves mechanical, microstructural, UV, and moisture barrier properties of the chitosan film due to cross-linking interactions, resulting in robust, foldable packaging film. Active TCE film exhibits high antioxidant property due to polyphenols. These films also exhibited low wettability and showed hydrophobicity than neat CH films which is essential for meat packaging. These biodegradable films offer an eco-friendly end-of-life option when buried in soil. TCE-loaded films effectively control spoilage organisms, prevent biochemical spoilage, and maintain shrimp freshness compared to neat CH films during refrigerated condition. The active TCE film retains sensory attributes better than neat chitosan, aligning with consumer preference. The developed edible and active film from waste sources might offer sustainable, alternative packaging material with a lower carbon footprint than petroleum-based sources.

Thiophene organic molecules in-situ grafted mesoporous carbon promote high stable and high kinetic lithium-sulfur batteries

Lithium‑sulfur (LiS) batteries are widely regarded as the promising battery system that meet the high energy density requirement up to 500 Wh kg−1. However, the serious shuttle effect and poor reaction kinetics seriously slow down the practical application of LiS batteries. For both solid and liquid LiS batteries, holding sulfides by adsorptive and catalytic host is an indispensable strategy to improve their reaction kinetic. Carbonaceous materials have been widely used as the sulfur hosts due to their easy controlled morphologic, lightweight and low-cost. However, these advantages were usually shelved by their low wettability and poor adsorption to polysulfides. In this study, a high active and stable carbonaceous host was synthesized by in-situ grafting thiophene molecules on mesoporous carbon. Sulfur was further bond on the thiophene molecules to form an extremely stable electrode structure. More importantly, the electron-rich conjugated thiophene molecules, which with high ionic and electronic conductivity, can effectively improve the reaction kinetics of LiS batteries. This simple and reproducible cathode modification strategy provides a reliable reference for realizing the practical application of LiS batteries.

Effects of peening duration on surface and wear properties of aircraft graded AA2017 alloy

This investigation addresses the effects of peening duration during SP on surface properties of AA2017 alloy. SP performed with different durations (0, 70, 140 and 210 s) and imparts the modification in the surface region. Alloy strength and structural parameters like crystallite size (D), dislocation density (ρ) microstrain (ε) and lattice constant (a) are increased with SP duration till 140 s. After 210 s, these properties declined due to the effect of softening caused by rise in surface temperature through over peening duration, and exhibited dynamic recovery. Severe plastic deformation developed by SP, created rough surface in all SPed samples and shows responsible for low wettability, high contact angles and low surface energy in comparison with AR sample. The SP140 exhibited maximum hardness (234 ± 7.1 HV) and maximum residual compressive stress (RCS) (−51 MPa) as compared with that of AR sample shown 70 ± 2.1 HV and 20 MPa respectively. Also, the cross-sectional measurements over a thickness of 200 μm confirmed their improvement. These results favoured for SP140 sample to yield lower wear rate about 0.776 mm3/ KN-m compared to AR sample (1.046 mm3/ KN-m). Further increase in shot peening duration to 210 s induces softened layer by rise in surface temperature and presence of Cu as major alloying element in AA2017 exhibits superior thermal conductivity and resulted in detrimental effect on wear resistance. The combination of several factors such as structural parameters, RCS and hardness in the surface region of SP140 sample are responsible to develop the wear resistance of AA2017 alloy.

Magnetorheological fluids: A comprehensive review

The magnetorheological (MR) fluids contain magnetic micro-sized iron particles, non-magnetic-based fluid, and some additives in order to mitigate sedimentation and agglomeration. The various carrier fluids used in the preparation of MR fluids are mineral oil, silicon oil, castor oil, soybean oil, kerosene, synthetic oils, honge oil, organic oil, water-based oils, etc. However, for obtaining better vibration control, silicone oil is the most preferred one due to its higher viscosity index, lower friction characteristics, higher flash point, and higher shear strength. The MR fluids have various application areas such as dampers, prosthetic knees, valves, brakes, clutches, finishing processes etc. The dampers containing MR fluids are used in automobile cushioning for enhancing passenger comfort and MR suspensions significantly improve steering stability in vehicles. In case of MR brakes, the braking torque on the rotating disks is controlled using the generated shear stress. The carbonyl iron (CI) particles exhibit better rheological characteristics as compared to electrolytic iron (EI) particles. The use of MR fluids produces stable and natural limb movement in orthoses, lower limb prostheses, and exoskeletons. The MR fluids also prove to be very significant in polishing applications. There are various issues with preparation methods and difficulties in the storage of MR fluids. The problems encountered in the synthesis of MR fluids include sedimentation, agglomeration, in-use thickening, corrosion, erosion, etc. The impact of particle proportion, particle shapes, and size has been influential in evaluating MR characteristics. The viscosity and shear stress of MR fluid have been mitigated at higher values of temperature and even CI particles get oxidized at higher temperatures. The CI particles as compared to EI particles are the majority favourable particles used for dispersing state within the MR fluids due to their higher value of saturation magnetization, more availability, and lesser cost. The small-sized particles led to lower wettability, whereas larger-sized particles accounted for an increased sedimentation rate. The currently available MR fluids cost is still on the higher side and the preparation of economical MR fluid is still a big challenge for the researchers. The MR fluids storage is also a big concern. The future scope of MR fluid may be in heavy industries such as nuclear, shipbuilding, oil and gas, space and aviation, etc. to achieve the desired damping response.

SiO2 Nanoparticle Coating to Enable Polyethylene-Based Na-Ion Battery Separators

The increasing demand for Li-ion batteries (LIBs), pushed even more by the electrical vehicle industry, has highlighted the concern with the scarcity and uneven distribution of LIB raw materials. Electrochemical energy storage based on alternative chemistries, once properly developed, may provide sufficient energy density to partly supply that demand, reducing the dependence on Li natural reserves. Among the studied chemistries, Na-ion-based storage is currently attracting a lot of research attention. This is partly due to the similarities between Li and Na, which allow for the utilisation of analogous materials and methods already in place for LIBs. However, not every component of LIBs can be directly applied to Na-ion batteries (SIB).[1] This is the case for battery separators, the membranes used to avoid physical contact between the two battery electrodes to prevent short circuiting while conducting ions from one battery pole to the other. Porous polyolefin films, such as polyethylene (PE) and polypropylene (PP), have been successfully used in LIBs, but are not compatible with SIB electrolytes. In the latter case, issues arise from the poor wettability of the separator with the electrolyte, which leads to low ionic conductivity, and creates an uneven flux of ions that can cause cell failure. To address this issue, previous reports have shown that the presence of inorganic oxides such as ZrO2 [2] and SiO2 [3] on polyolefin films can increase the affinity of the separator with commonly used LIB and SIB electrolytes. Moreover, ceramic-modified films also show higher thermal stability and hindered thermal shrinkage, which improves battery safety.In this work, we investigated PE coated with spherical SiO2 particles (designed by Glantreo, Ireland) with different sizes of 85 and 200 nm. The coatings were made by tape casting both sides of a PE film with slurries containing SiO2 particles and a binder. Binder type, SiO2 concentration and SiO2/binder ratio were optimized for each particle size. The obtained films were characterized by scanning electron microscopy and infrared spectroscopy, and were compared regarding their wettability, thermal stability, and ionic conductivity. The films were tested as separators in hard-carbon half-cells with 1 mol/L NaClO4 in either diethylene glycol dimethyl ether (DEGDME) or ethylene carbonate (EC)/ propylene carbonate (PC) electrolyte. With carbonate-based electrolyte, PE has very low wettability and cells short circuit within the first cycle. However, SiO2-PE samples showed higher wettability, which allowed for cycling at low current densities. In DEGDME-based electrolyte, cells with PE separator presented capacity fade, with 50% capacity loss after 250 cycles at 400 mA/g. On the other hand, cells with SiO2-PE separator had stable cycling for more than 300 cycles and no short-circuiting was observed, even when high active mass loading electrodes (8 mg/cm2) were used. These are promising results showing that a surface layer of SiO2 particles can make PE a viable option for SIB separators.

Nanocomposite synergy for enhanced oil recovery: Macro and micro analysis of CeO2/montmorillonite nanofluids in carbonate and sandstone reservoirs

Cerium (IV) oxide has shown great potential for serving as a mutually advantageous conjunction material when applied in a synergistic manner of use with other chemicals thanks to its oxygen storage capacity. Recently, many researchers have elaborated on novel synthesis methods for achieving nanocomposites (NCs) that combine inherent properties of nano-sized CeO2 with those of montmorillonite, as a low-cost base substance. CeO2/Montmorillonite nanocomposite synthesized by application of an environmentally friendly reducing and stabilizing agent. The success of the synthesis was verified by analytical techniques including Field-Emission Scanning Electron Microscopy, Thermo-Gravimetric analysis, Energy-Dispersive X-ray Spectroscopy and Mapping, X-Ray Diffraction analysis, Fourier-Transform Infrared spectroscopy. Nanofluids were prepared by dispersing the synthesized NCs, at different concentrations as aqueous colloidal solutions and then studied for investigating the nanofluid colloidal stability. Experimental studies were undertaken on the nanofluid functioning subjects of the fluid/fluid and fluid/fluid/rock interactions area in both macro and micro scales. Macro investigations of interfacial tension and wettability alteration and also micro-analysis of microfluidic injections with proper visualizations of created effects within pore structures were carried out. The results confirmed the proper synthesis of the NC and its stability in water-based nanofluids. CeO2 nano clays showed nearly 33 % optimization of the interfacial tension (IFT) (i.e., IFT decreased from the initial value of 27 to 18 mN/m at the NC concentration of 1000 ppm). However, their effect on the alteration of wettability was significant. Indeed, at the optimum concentrations, the contact angle decreased from 151° to 19.38° at the concentration of 500 ppm for carbonate lithology (87.1 % optimization) and also it decreased from 135.5° to 18.73° at the concentration of 1500 ppm for sandstone lithology (86.1 % optimization). The effect of wettability alteration for carbonate rocks was reported to be high enough for changing the wettability to a strong water-wet state while the wettability alteration for sandstone lithology was measured to be low. Both wettability alteration studies and micro visualizations validated the strong and low wettability alteration for carbonate and sandstone lithology systems. Also, the emulsion analysis was carried out on the micro-scaled images of the pores and throats with their containing fluids by a new method of color saturation investigation which showed a promising new emulsion analysis method for micro-scaled experiments.