Surface Water Contact Angle Research Articles

Surface Hydrophilic Modification of Polypropylene by Nanosecond Pulsed Ar/O2 Dielectric Barrier Discharge.

Polypropylene (PP) membranes have found diverse applications, such as in wastewater treatment, lithium-ion batteries, and pharmaceuticals, due to their low cost, excellent mechanical properties, thermal stability, and chemical resistance. However, the intrinsic hydrophobicity of PP materials leads to membrane fouling and filtration flux reduction, which greatly hinders the applications of PP membranes. Dielectric barrier discharge (DBD) is an effective technique for surface modification of materials because it generates a large area of low-temperature plasma at atmospheric pressure. In this study, O2 was added to nanosecond pulsed Ar DBD to increase its reactivity. Electrical and optical diagnostic techniques were used to study the discharge characteristics of the DBD at varying O2 contents. The uniformity of the discharge was quantitatively analyzed using the observed discharge images. Water contact angle measurements were used to assess the surface hydrophilicity of polypropylene. The surface morphology and chemical composition of the PP materials before and after treatment were analyzed using field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results show that the moderate addition of O2 enhances surface hydrophilicity and the uniformity of the modification. By increasing the O2 addition from 0% to 0.1%, the average power increased from 4.19 W to 5.79 W, and the energy efficiency increased from 17.78% to 21.51%. The water contact angle of the DBD-treated PP showed a tendency to decrease and then increase with increasing O2 content, with the optimum O2 addition determined to be 0.1%. Under this condition, the water contact angle of the PP surface decreased by 31.88°, which is 52.31% lower than the untreated surface. O2 increases the number of oxygen-containing polar groups (-OH, C=O, and O-C=O) on the surface of the material, and deepens and densifies the grooves on the surface of the PP material, resulting in an increase in the hydrophilicity of the PP surface.

Engineered Polystyrene‐Zirconium Dioxide Nanocomposite With Enhanced Optical Properties

ABSTRACTThe demand for transparent polymers with high‐refractive indices (RIs) is increasing due to their versatility; however, low RIs also hold significance. Engineering the RI of polymer nanocomposites is crucial which benefits industry and research. The study investigates the influence of ZrO2 nanoparticles on the optical and surface properties of the polystyrene matrix. UV–Vis spectroscopy confirms that transparency is maintained with a light transmittance of 90 even with a ZrO2 loading of 16 wt%, while ellipsometry shows a steady increase in the RI due to the incorporation of nanoparticles. The RI of composites exceeds that of pure polystyrene (RI: 1.3–1.7) and utilizes the RI of ZrO2 (> 2.00) without altering the sample thickness. The microscopic image shows uniform distribution of particles up to 8 wt%, with slight agglomeration at higher contents. Scanning electron microscopy examination shows that the ZrO2 nanoparticles (20–150 nm) form loose agglomerated structures, while atomic force microscopy examination shows aggregate formation at 16 wt%. The addition of ZrO2 increases the surface roughness and water contact angle up to 4 wt%, which is related to the concentration of the nanofiller and the minimal interaction between ZrO2 and water. The results demonstrate the potential of ZrO2‐loaded nanocomposites for applications requiring high RIs and optical transparency.

Hydrophobic modification and durability protection of cotton garment fabric surfaces by graphene oxide/PGMA composite coatings

Cotton fiber fabric with practicability and functionality attracts much attention and plays an important role in many occasions. However, its surface contains many hydroxyl groups to show a hydrophilicity, leading to easy adhesion to stains to limit the application. In this work, polyglycidyl methacrylate (PGMA) was used as an oily and flexible matrix and graphene oxide (GO) particles were used as a filler. PGMA/GO composite modified fabrics with hydrophobicity, self-cleaning feature and wear resistance were prepared by constructing surface coatings. Compared with original fabric, PGMA/GO composite modified fabric has a surface hydrophobicity attributed to organic oily characteristic of PGMA, and high surface roughness from GO surface enrichment. The reasonable GO content (1 wt%) in composite coating makes the modified fabric exhibit the best overall performance (surface water contact angle of ~ 151.7°; chromatism of ~ 2.4; large water contact angle of ~ 140.2° after 200 surface wear cycles). This work provides an effective method for an industrial production of high-performance waterproof cotton garment fabrics.

Crystallization-driven formation of cluster assemblies on surface for super-hydrophobic poly (L-lactic acid)/ZnO composite membrane.

The poly(L-lactic acid) (PLLA)/ZnO composite membrane with cluster assemblies microstructure was constructed by a combination of non-solvent induced phase separation (NIPS) and the Breath-Figure method. In this novel method, the controllable diffusion rate between solvent and non-solvent was introduced to the system by adjusting the non-solvent solubility parameters. The humidity was adjusted to control non-solvent solubility parameters in the Breath-Figure method, which avoids the instantaneous phase separation induced by direct coagulation of water droplets. Hydrophobic modified ZnO nanoparticles were used as heterogeneous nucleation points to induce PLLA crystallization and formation of micro-nano structures. Controlling molecular chain growth with crystal nuclei as templates and constructing cluster assemblies microscopic morphology at 99% humidity, and the size of the cluster decreases gradually from 10μm to 3μm as the nanoparticles content increased up to 5wt%. The surface water contact angle could reach 153.8° with cluster morphology. In addition, the porous structure formed by the polymer-lean phase could increase the porosity to 93.1% and exhibit an excellent oil absorption capacity up to 12.64g/g. It is foreseeable that porous PLLA/ZnO composite membranes have potential applications as biodegradable oil-water separation materials.

A Novel PVDF Ultrafiltration Membrane Modified by C60(OH)n-Ag.

Ultrafiltration membranes in the fields of water treatment and biomedicine should have high permeability as well as antibacterial and antifouling capabilities. In this study, based on the hydrophilicity of fullerol (C60(OH)n) and the bacteriostatic properties of silver (Ag), a fullerol-silver (C60(OH)n-Ag) complex was prepared as a multifunctional additive. A polyvinylidene fluoride (PVDF)-composited C60(OH)n-Ag ultrafiltration membrane (C60(OH)n-Ag/PVDF) was prepared by immersion precipitation phase transformation. Addition of the C60(OH)n-Ag complex improved the permeability and retention of the traditional PVDF membrane. Compared with the traditional PVDF membrane, the surface water contact angle of the modified PVDF and C60(OH)n-Ag ultrafiltration membrane was reduced from 75.05° to 34.50°, its pure water flux increased from 224.11 L·m-2·h-1 to 804.05 L·m-2·h-1, the retention rate on bovine serum protein was increased from 75.00% to 96.44% and the flux recovery rate increased from 64.91% to 79.08%. The C60(OH)n-Ag/PVDF ultrafiltration membrane had good inhibitory effects on Escherichia coli and Staphylococcus aureus, while the PVDF ultrafiltration membrane had no obvious inhibitory effects.

Comparative evaluation of human oral fibroblast proliferation on 3D-printed zirconia and silicon nitride as new ceramic materials for implant abutment.

Cell adhesion and subsequent proliferation on material surfaces depend on the physical and chemical characteristics of the material. There is a lack of literature on human gingival fibroblast proliferation on comparatively newer additively manufactured materials like silicon nitride. This study focused on the physical characteristics of the materials with the aim to compare the adhesion and proliferation of human gingival fibroblasts on additively manufactured silicon nitride (AMSN) with additively manufactured zirconia, conventional milled titanium (MTi), and milled zirconia. Surface roughness and water contact angle were measured by profilometer and goniometer, respectively. CCK-8 assay was done to assess the cell growth at 24h (day 1), 48h (day 2), and 72h (day 3) in the same well. The morphologies of fibroblasts after cell attachment and proliferation were evaluated using scanning electron microscopy (SEM) after 72h. At the end of 24h (day 1) additively manufactured zirconia showed the best proliferation among the experimental groups, which was around 50% of the positive control group proliferation. There was no statistically significant difference among the experimental groups. At 48h (day 2) and 72h (day 3), a loss of cell growth was seen in almost all the experimental group wells. A positive cell proliferation on the AMSN was observed on day 3. Comparable cell proliferation was observed in the experimental groups. No conclusive correlation could be drawn between cell proliferation and surface roughness and water contact angle values in the experimental groups.

Nanofiltration Membranes Containing a Metal-Polyphenol Network Layer: Using Casting Solution pH as a Tool to Tailor the Separation Performance.

Thin-film composite (TFC) membranes containing metal-polyphenol network (MPN) selective layers were fabricated using a supramolecular self-assembly between tannic acid (TA) and ferric ion (Fe3+). The TA-Fe3+ thin film was coated on a porous polyacrylonitrile support using aqueous solutions of TA and FeCl3 via a layer-by-layer deposition technique. The pH of the TA solution was used as a tool to alter the membrane characteristics. The surface porosity and water contact angle of the fabricated membranes gradually decreased as the pH of TA casting solutions was increased from 3 to 8.5 for both single-layered and double-layered TA-Fe3+ TFC membranes. This allowed us to tune the water permeance and the retentions of water-soluble neutral and anionic molecules by the MPN membranes by varying the pH of the casting solution. It has been shown that the water permeance decreased from 184 to 156 L·m-2·h-1·bar-1 for single TA-Fe3+ layer coated membranes when the pH was increased from 3 to 8.5, while it declined from 51 to 17 for the double TA-Fe3+ layer. Anionic solutes in aqueous solutions were highly retained compared to neutral components as the TFC membranes had a negative surface charge. Retentions of 95 and 90% were achieved for naphthol green B and orange II dyes by a double-layered M4 membrane fabricated at pH 8.5, while only 13% retention was found for the neutral riboflavin. The neutral dye riboflavin permeated 30.8 times higher than the anionic dye naphthol green B during a mixed dye filtration test through the TFC membrane prepared by using a TA solution of pH 8.5. To the best of our knowledge, this is the highest selectivity of a neutral/anionic dye pair so far reported for a TFC membrane having an MPN selective layer. Moreover, fouling tests have demonstrated that the MPN separation layers exhibit robust stability and adequate antifouling performance with a flux recovery ratio as high as 82%.

Design and characterization of multicolor water-repellent coatings: Impact of alkyl chain length on surface properties

Fabrication of functional colored water-repellent surfaces is very important for many industrial applications. Here, various colorful surface coating materials having water repellent property, chemical, thermal and UV light resistance and self-cleaning property were prepared using activated halloysite nanotube loaded with dye (A-Hal/dye), different alkoxysilanes (methyltriethoxysilane (MTES), octyltriethoxysilane (OTES) and hexadecyltrimethoxysilane (HDTMS)), and tetraethoxysilane and their coatings were performed on various substrates to determine the effect of alkyl chain length of alkoxysilane compound used in the coating formulation on the surface properties of colorful surfaces. Characterization studies of the synthesized surfaces or coated materials were performed using electron microscopy (TEM and SEM), SEM-mapping, FTIR, XRD, XPS and thermal gravimetic analysis techniques. Water contact angle (WCA) of glass surfaces coated with A-Hal/MB/MTES, A-Hal/MB/OTES and A-Hal/MB/HDTMS materials was found to be 148.0, 156.2 and 159.3°, respectively. The use of an alkoxysilane compound with long functional alkyl chain group in the coating formulation improved the water-repellent property of surface, while it slightly weakened the mechanical stability of the colorful surface. Polydimethylsiloxane (PDMS) coating, which were applied on colorful surfaces, improved the mechanical, thermal, chemical and environmental stability of coating, but decreased the water-repellent property of coated colorful surfaces. Fabricated coating materials having different colors were successfully used to coat various substrates such as glass, filter paper, wood, and cotton fabric. The results of this study show that A-Hal/dye/HDTMS coating materials prepared here are of a great potential in the fabrication of functional surface coatings.

Self-assembled ILs-PVA micelle nanostructure impart the pervaporation membrane with high ethanol dehydration performance

Achieving strong interaction with the targeted composition and constructing abundant transport channels is crucial to obtain the pervaporation (PV) membrane with high selectivity and flux. Here, three ionic liquids (ILs) were screened out based on their relative selectivity and capacity targeting for bioethanol dehydration by COSMO-RS. The interaction energies analysis between ILs, EtOH, and H2O suggests that the ILs can form strong hydrogen bonds with water and disrupt the hydrogen bond in the EtOH–H2O azeotropic mixture, which is beneficial for improving the selectivity. Furthermore, driven by the multiple hydrogen bonds, electrostatic interactions, and van der Waals forces, ILs could self-assemble with polyvinyl alcohol (PVA) to fabricate the PV membrane with well-ordered micelle nanostructure, as its structure was revealed by MD simulations. The formation of the ILs-PVA micelle dramatically influenced membrane surface morphology, roughness, and water contact angle, providing an extra transport channel for the membrane. The optimal membrane (at the cmc point) exhibited a superior ethanol dehydration separation factor of 1627, along with a flux of 684 g/m2h at 50 °C. It can be expected that this novel self-assembled ILs-PVA micelle nanostructure strategy will find promising applications in other azeotropic mixture separation processes, like ethanol-ethyl acetate, water-butanol, etc.

Jade powder/PLGA composite microspheres for improved performance as potential bone repair drug carrier

Poly (lactic-co-glycolic acid) (PLGA) has been widely used as drug delivery carrier or scaffold for bone repair due to its good biocompatibility, biodegradability, and degradation rate controllability. However, defects, like acidic degradation by-products, are associated with PLGA and restrict its practical applications. Jade powder, leftover from jade polishing process, is a natural material rich in elements of Ca, Si, and Mg while biocompatible and antibacterial. Herein, jade powder/PLGA composite microspheres with different mass ratios were prepared by emulsion solvent evaporation method under the optimized conditions. Characterization from SEM, EDS, FTIR, and surface water contact angle measurements indicated jade powder was successfully combined with PLGA and improved the surface wettability of the microspheres. Moreover, it was proved, through in vitro simulated body fluid test as well as adipose stem cell osteogenesis analysis, that jade powder addition enhanced the pH buffering capacity of the composite microsphere for simulated body fluid, and promoted the in vitro osteogenic activity of adipose stem cells at a certain amount. This study provides new ideas to employ jade powder, a natural material otherwise thrown away as solid waste, for improvement on PLGA performance in bone repair or potentially other biomedical fields.

Effect of admixed silicone emulsion on water and chloride transport properties of concrete

The addition of silicone is effective method for improving both surface and internal hydrophobicity of concrete, thus clarifying its effect on transport property of concrete is very important. In this study, both water and chloride transport properties of concrete incorporated with three silicone emulsions based on different active ingredients (silane oligomers or silane monomers) were evaluated and investigated. The results show that all three silicone emulsions exhibit no obvious negative effect on hydration and microstructure of cement paste; however, the admixed silicone emulsions increase both the thickness and porosity of ITZ in concrete. Therefore, the admixed silicone emulsions result in reduced compressive strength of concrete. Further, the incorporated silicone emulsions efficiently increase surface and internal water contact angle of concrete, thus mitigating both water absorption and chloride transport in concrete. Due to more pronounced interaction between silane oligomers and hydration products based on molecular dynamics simulation, the beneficial effect on improving hydrophobicity of concrete and halting water and chloride transport is more significant for the admixed silicone emulsion with silane oligomers as active ingredient.

Research on a novel non-uniform and asymmetric ultrasonic vibration system

Abstract A new type of non-uniform and asymmetric ultrasonic vibration system (UVS) is proposed and applied to the turning process. The research results show that the design theory of the non-uniform and non-symmetric UVS is accurate and reliable. The theoretical design frequency and modal simulation frequency error of ultrasonic vibration turning system is only 2.5%. The designed non-uniform and non-symmetric UVS has excellent vibration performance and stability, and the established simulation model can predict surface microtexture accurately. The vibration mode output by the non-uniform and non-symmetric UVS is longitudinal-bending vibration, and the actual vibration performance is excellent. Compared with conventional cutting, the addition of longitudinal-bending ultrasonic vibration under the same conditions can give the machined surface a microscopic textured structure, reduce surface roughness and water contact angle, and improve surface wettability. The minimum surface roughness obtained in the experiment is 1.005 μm. The orthogonal experiment results show that there is a correlation between the machining parameters, surface micro-structure parameters, surface wettability, and surface roughness.

Ultra-Pressurized Deposition of Hydrophobic Chitosan Surface Coating on Wood for Fungal Resistance.

Fungi (Neolentinus lepideus, Nl, and Trametes versicolor, Tv) impart wood rot, leading to economic and environmental issues. To overcome this issue, toxic chemicals are commonly employed for wood preservation, impacting the environment and human health. Surface coatings based on antimicrobial chitosan (CS) of high molar mass (145 × 105 Da) were tested as wood preservation agents using an innovative strategy involving ultra-pressurizing CS solutions to deposit organic coatings on wood samples. Before coating deposition, the antifungal activity of CS in diluted acetic acid (AcOOH) solutions was evaluated against the rot fungi models Neolentinus lepideus (Nl) and Trametes versicolor (Tv). CS effectively inhibited fungal growth, particularly in solutions with concentrations equal to or higher than 0.125 mg/mL. Wood samples (Eucalyptus sp. and Pinus sp.) were then coated with CS under ultra-pressurization at 70 bar. The polymeric coating deposition on wood was confirmed through X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) images, and water contact angle measurements. Infrared spectroscopy (FTIR) spectra of the uncoated and coated samples suggested that CS does not penetrate the bulk of the wood samples due to its high molar mass but penetrates in the surface pores, leading to its impregnation in wood samples. Coated and uncoated wood samples were exposed to fungi (Tv and Nl) for 12 weeks. In vivo testing revealed that Tv and Nl fungi did not grow on wood samples coated with CS, whereas the fungi proliferated on uncoated samples. CS of high molar mass has film-forming properties, leading to a thin hydrophobic film on the wood surface (water contact angle of 118°). This effect is mainly attributed to the high molar mass of CS and the hydrogen bonding interactions established between CS chains and cellulose. This hydrophobic film prevents water interaction, resulting in a stable coating with insignificant leaching of CS after the stability test. The CS coating can offer a sustainable strategy to prevent wood degradation, overcoming the disadvantages of toxic chemicals often used as wood preservative agents.

Anti-Reflection Property of SiO2 Composite Films for Solar Cell

In this study, anti-reflection property of SiO2 based composite films were investigated. For this purpose, SiO2/TiO2, SiO2/ZnO and SiO2/TiO2/ZnO composite films were prepared using a sol-gel technique and coated on glass slides. Polyethylene glycol (PEG) with molecular weight of 1500 g/mol was inserted into the SiO2 composite film as a porogen to decrease the refractive index and improve the anti-reflection property of the as-prepared film. The SiO2 films with pore structures were successfully obtained. The PEG modified SiO2/ZnO (SiO2/PEG/ZnO) film provided a water contact angle close to the water contact angle of a superhydrophilic surface. In addition, the SiO2/PEG/ZnO film exhibited the highest average transmittance of 92.7% higher than that of the uncoated glass slide. The photovoltaic conversion efficiency of the solar cell coated with the SiO2/PEG/ZnO film was very close to that of the solar cell without the film coating. Hence, the results exhibited that the SiO2/PEG/ZnO film with anti-reflection and photovoltaic conversion efficiency has a potential application on solar cells.

Green superhydrophobic surface engineering of PET fabric for advanced water-solvent separation

This paper presents the preparation of the PET membrane for effective organic solvent separation achieved through an advanced superhydrophobic surface engineering of PET fabric utilizing biomimicry and a green chemistry approach. The superhydrophobicity of the PET surface was reached through a hierarchical nanocomposite coating that involved the integration of biomimetic polydopamine (PDA) coating, green-synthesized zinc oxide (ZnO) nanoparticles (NPs), and non-fluorinated quaternary ammonium cation silane (Si-QAC) coverage. The morphology and surface chemical composition of the resultant Si-QAC/ZnO/PDA@PET membrane were characterized by SEM, EDS, FT-IR, XRD, and AFM analysis. The surface topography and water contact angle were also correlated with surface roughness and its superhydrophobicity. The resulting Si-QAC/ZnO/PDA@PET membrane exhibited promising superhydrophobic properties, characterized by a water contact angle ranging from 150° to 160° and a roll-off angle between 5° and 2° as well as stability against severe conditions, including acidic and alkaline exposure, mechanical abrasion, and UV radiations. Moreover, the Si-QAC/ZnO/PDA@PET membrane exhibited bacterial repulsive properties against E. coli and Staphylococcus sp. The separation efficiency of various aliphatic and aromatic organic solvents (n-hexane, toluene, chloroform, and petroleum ether) from water higher than 90 % was also observed, making the membrane a potential candidate for different industrial applications, particularly for the separation of organic solvents from water.

Superhydrophobic nanocellulose aerogel for thermal insulation and thermal resistance up to 1300 °C

Nanoellulose aerogel (NCA) has the advantages of good flexibility, low density, and excellent thermal insulation. Its raw materials are widely sourced, renewable, and degraded, thus NCA has attracted significant interest ofresearchers in the field of insulation. However, low strength, hydrophilicity, and flammability seriously hinder its application. Here, a superhydrophobic NCA (Si-PA-PAE-NCA) with a multiscale structure is reported. Si-PA-PAE-NCA exhibits excellent compression strain (up to 8.674 MPa with strain at 80 %). A low thermal conductivity of 23.9 mWm−1 K−1 endows this aerogel with superior thermal insulation property. Compared to only the surface superhydrophobility of other NCAs, both the surface and interior water contact angles of Si-PA-PAE-NCA are up to 157°. Owing to this distinguished superhydrophobicity, Si-PA-PAE-NCA can maintain its stable thermal insulation property in a high humidity environment (90 % humidity). Importantly, Si-PA-PAE-NCA can withstand 1300 ℃ flame for 70 min, far exceeding previously reported NCAs. Besides, this aerogel exhibits the highest LOI value (45.9 %) ever recorded for NCAs thus far. Notably, there is no inorganic substance within the aerogel. Together with its scalability, sustainability, and degradability, Si-PA-PAE-NCA will have great application prospects in the insulation area.

Preparation of Antistatic Polyester Fiber via Layer-by-Layer Self-Assembly

Polyester fibers tend to generate static electricity during the weaving and application processes, posing a threat to their production. Enhancing the water absorbency and electrical conductivity of polyester fibers themselves is an effective approach to improving their antistatic properties. In this study, multifunctional chitosan (CS), sodium phytate (SP), and Cu2+ were loaded on polyester fibers through layer-by-layer (LBL) self-assembly. The antistatic and water absorption capability of the modified polyester fibers was investigated by designing different process parameters combined with a surface resistance test and water contact angle tests. The antistatic property test results confirmed the positive effect of CS and Cu2+ on discharging electrostatic charge. Within a definite scope, with the increase in the number of assembly layers, assembly duration, and the concentration of the assembly substances, the wettability of the modified polyester fibers became more favorable and the antistatic effect became more remarkable.

The effect of low-temperature plasma pretreatment on the biodegradability of polyethylene films

ABSTRACT With the increasing focus on environmental friendliness and sustainable development, extensive research has been conducted on the biodegradation of plastics. The non-hydrolyzable, highly hydrophobic, and high-molecular-weight properties of polyethylene (PE) pose challenges for cell interaction and biodegradation of PE substrates. To overcome these obstacles, PE films were treated with low-temperature plasma before biodegradation. The morphology, surface chemistry, molecular weight, and weight loss of PE films after plasma treatment and biodegradation were studied. The plasma treatment decreased the surface water contact angle, formed C–O and C = O groups, and decreased the molecular weight of PE films. With the increased pretreatment time, the biodegradation efficiency rose to 2.6% from 0.63% after 20 days of incubation. The mechanism was proposed that the surface oxygen-containing groups formed by plasma treatment can facilitate the bio-accessibility and be further decomposed and utilised by the microbes. This study provided an effective and rapid pretreatment strategy for improving biodegradation of PE.

Impact of Atomic Defects on Water Contact Angle of 2D Molybdenum Disulfide Surfaces.

Interfacial dynamics within nanofluidic systems are crucial for applications like water desalination and osmotic energy harvesting. Understanding these dynamics can inform the rational optimization of two-dimensional (2D) materials and devices for such applications. This study explores the wetting behavior of realistic 2D MoS2 surfaces incorporating vacancies and atomic steps, known as atomic defects. We employ a combined density functional theory (DFT) and molecular dynamics (MD) computational approach to elucidate the influence of atomic defects on the MoS2-water interface. DFT calculations are utilized to determine the charge distribution within MoS2. Subsequently, free energy calculations are obtained through MD simulations of the MoS2-water interface. Our findings underscore the importance of incorporating atomic defects into MoS2 surfaces for accurate water contact angle (WCA) predictions in nanofluidic simulations, particularly when using Abal et al. force field parameters. However, the force field developed by Liu et al. yielded more accurate results for pristine MoS2 surfaces. While these parameters provide reliable outcomes for pristine MoS2 surfaces, their application to surfaces with defects may lead to underestimation of WCA. This highlights the critical need for realistic surface representations in nanofluidic modeling to accurately capture the complex interactions between water and MoS2 materials.

A green bulk modification for imparting a green VIPS membrane with antifouling properties

BackgroundMembrane preparation and membrane modification processes have long involved the use of toxic solvents. The present work proposes to only use envrionmentally-friendly solvents for both the fabrication and the surface modification of hydrophobic microfiltration membranes. In addition, coating processes for membrane modification are essentially surface modification processes. However, spray-coating may be a suitable method for both surface and bulk modification. MethodsAfter dissolving poly(vinylidene fluoride) in dimethylsulfoxide, membranes were formed by the vapor-induced phase separation process, and then modified using an aqeous solution of an amphiphilic copolymer containing poly(ethylene glycol) methyl ether methacrylate units. Then, a variety of physicochemical techniques were employed to characterize the membrane structure and prove the effectiveness of the surface/bulk modification. Antifouling tests in static and dynamic conditions were conducted. Significant findingsIt is possible to reduce the water contact angle of the top surface of the membrane from 135° to 0° and that of the bottom surface from 126° to 0° within <10 s, indicating successful hydrophilization of the membrane on the one hand, and top-to-bottom modification, despite solely exposing the top surface to the spray, on the other hand. This conclusion was confirmed by deidcated surface chemistry analyses. Besides, the membranes maintained their original highly porous and symmetric structure with light effects on surface porosity and pore size following the spray-coating process. The drasting improvement of hydrophilicity resulted in effective mitigation of fibrinogen adsorption (reduced by 85 %) and Escherichia coli adhesion (reduced by 86 %). Fouling during cyclic filtration involving a bacterial suspension was also effectively reduced with a flux recovery ratio of 53 % (against 37 % for a commercial hydrophilic membrane) and an irreversible flux decline ratio of 47 % (against 63 % for a commercial hydrophilic membrane) in the conditions of the test.