Surface Wetting Properties Research Articles

Bamboo belts with variable fiber cell angles for winding applications: Development of a novel manufacturing technique and assessment of performance feasibility

In response to the environmental impacts of synthetic fiber production and disposal, coupled with limitations in the existing continuous processing methods for plant fibers, this study proposed a novel manufacturing approach for preparing wide and continuous bamboo winding belts. The current application scenarios of bamboo belt winding products are limited because the reinforcement orientation cannot be optimized due to the inherent stiffness of bamboo belts, and the variety of bamboo belt types is limited. This study employed two representative types of bamboo belts: bamboo slivers and thin bamboo veneers, which had varying cross-sectional aspect ratios. Verification demonstrated that this method enabled the production of bamboo winding products with any reinforcement orientations ranging from 0 radians to π radians. This addressed the challenge of optimizing reinforcement orientation in bamboo winding products and was anticipated to broaden the application of this method to other winding units with unidirectional reinforcement. Additionally, the performance feasibility of the two bamboo winding belts prepared using this method was evaluated in terms of microstructure, surface wettability, and mechanical properties. The bamboo slivers and thin bamboo veneers, with their rigid-flexible structure, hydrophilicity, and non-catastrophic fracture characteristics, enhanced their winding potential. These wide, continuous, and rigid-flexible features of the bamboo winding belts held promise for their expanded applications in bamboo winding products, thus promoting sustainable and environmentally friendly manufacturing practices.

Sheep bone powder modified PVDF membrane for highlyefficient oil-in-water emulsion separation

BackgroundThe wetting properties and roughness modification of membrane surfaces are crucial for their application in emulsion separation. However, traditional membrane modification methods suffer from high cost, complex preparation, and secondary pollution. MethodsIn this study, a novel, simple, and economical interfacial engineering method was developed using tannic acid (TA), sodium alginate (SA), and sheep bone powder (BP) as raw materials. Through vacuum filtration, these materials were deposited onto polyvinylidene fluoride (PVDF) membrane to fabricate superhydrophilic/underwater superoleophobic filtration membrane (PDBS). BP induced surface roughness and wetting properties to the membrane, while preserving the porous structure of the substrate membrane. The complex formed by TA and SA encapsulated BP onto the surface of PVDF microfiltration membrane, enhancing its mechanical properties. Significant FindingsThe prepared membrane exhibited a membrane flux of 347 Lm−2h−1 bar−1 and a separation efficiency of 99.9 % for emulsified oil. Furthermore, after soaking in NaCl solution for 30 h, the membrane still showed excellent stability. Therefore, this study developed a new membrane surface modification strategy with promising application prospects in oily wastewater treatment.

Characterization of nanoceria-modified silicone soft liners: Surface morphology, hardness, wettability, cytotoxicity, and antifungal properties in artificial saliva – An in vitro study

Statement of problemSoft liners are essential for denture wearers, which aids in the healing of soft tissue injuries caused by rough denture base surfaces. Silicone soft liners, while effective, can accumulate biofilm over time, necessitating enhancement. PurposeThis in vitro study aimed to assess the efficacy of silicone soft liners incorporating varying concentrations of cerium oxide nanoparticles. Materials and methodsA stainless-steel die as per ISO standard 10139-2-2018 (35 × 6 mm), Using G*Power 3.0.10 software, 400 samples were prepared with 95 % confidence interval and 80 % power. Samples were divided into five groups: surface morphology (Group A), surface hardness (Group B), wettability (Group C), cytotoxicity (Group D), and antifungal property (Group E). Each group was subdivided based on cerium oxide nanoparticle concentrations. Samples were stored in artificial saliva until evaluation. Surface morphology was examined via scanning electron microscopy (SEM), surface hardness using Shore A Durometer, wettability by drop shape analysis, cytotoxicity via MTT assay, and antifungal properties using crystal violet staining.Data were assessed for normal distribution using Kolmogorov-Smirnov and Shapiro-Wilk tests. ResultsSEM analysis showed optimal nanoparticle dispersion in Group A2(0.25 %) and A3 (0.5 %). Group B2 (0.25 %) exhibited the lowest mean surface hardness, decreasing from day 1 to day 30. Group C3 demonstrated the most hydrophobic surface across days. Group D2 exhibited the least cytotoxicity at all time intervals. Group E4 displayed the highest antifungal activity. ConclusionWithin study limitations, silicone soft liners modified with 0.25 % and 0.5 % cerium oxide nanoparticles exhibited superior properties in surface hardness and cytotoxicity. Optimal surface morphology and wettability were observed with 0.5 % concentration, while antifungal efficacy peaked at 1 %. These findings suggest clinical potential for treating damaged oral tissues. Clinical implicationsSoft liners modified with 0.25 % and 0.5 % cerium oxide nanoparticles may benefit patients with oral tissue abuse, offering enhanced therapeutic properties.

Surface activity, wettability and foam properties of quaternary ammonium surfactants with C-F/Si-H double hydrophobic backbone

This paper reported the synthesis of a novel quaternary surfactant (PFAS-Si) containing the C-F/Si-H double hydrophobic skeleton and the surface properties of its aqueous solution, which were investigated in comparison with those of the aqueous solutions of the fluorosurfactant (PFAS-IEt) and silicone surfactant (TMSAC) with similar hydrophobic chain structures. The critical micelle concentration (CMC) and the corresponding surface tension value (γCMC) of the PFAS-Si solution were 0.0612 mmol/L and 21.02 mN/m, respectively, which indicated that the PFAS-Si could substantially reduce the surface tension of water, and showed excellent surface activity. Meanwhile, the thermodynamic parameters of the micellization process, aggregation behavior, wettability, and foam properties of PFAS-Si solutions were systematically investigated. On the TEM negative staining photographs, it can be clearly seen that the aggregates of PFAS-Si in aqueous solution exhibit hollow spherical vesicles. In addition, the PFAS-Si solution exhibited superb wettability, and could achieve wetting of PTFE sheets at a very low concentration (0.168 mmol/L). Not only that, the PFAS-Si solution also had excellent foaming ability and foam stability. This work provided a new preparation idea for the development of high-performance specialty surfactants.

Durable Superhydrophobic Aluminum Surfaces against Immersion and Hot Steam Impact: A Comparative Evaluation of Different Hydrophobization Methods and Coatings

Controlling the wettability properties of metallic materials and surfaces can enhance their applicability and improve their performance and durability in several fields, such as corrosion protection, heat transfer applications, self-cleaning, and friction reduction. Here, we present and compare some versatile fabrication methods that can provide aluminum surfaces with durable superhydrophobic performance which are suitable for heat transfer applications. To probe their stability in heat transfer applications, two evaluation protocols are designed, one which suggests immersion in hot water for several hours, and a second testing against the harsh conditions of hot steam impact. The superhydrophobic aluminum surfaces are fabricated by first creating micro or micro-nano roughness on an initially flat surface, followed by the minimization of its surface energy through two hydrophobization methods, one wet and one dry, thus creating a series of different coating materials. Surfaces are then evaluated by immersing them in hot water and exposing them to steam impact. It is demonstrated that despite the fact that all hydrophobization methods tested resulted in surfaces exhibiting superhydrophobic properties, only the ultra-thin Teflon-like coating, obtained after plasma deposition using C4F8 plasma, exhibited robust superhydrophobicity with hysteresis lower than 8° when immersed in water at 90 °C for 10 h. This surface also showed minimal wettability changes and was the only one to retain its hysteresis below 6° after 4 h of exposure to hot steam.

Temperature-Sensitive Sensors Modified with Poly(N-isopropylacrylamide): Enhancing Performance through Tailored Thermoresponsiveness.

The development of temperature-sensitive sensors upgraded by poly(N-isopropylacrylamide) (PNIPAM) represents a significant stride in enhancing performance and tailoring thermoresponsiveness. In this study, an array of temperature-responsive electrochemical sensors modified with different PNIPAM-based copolymer films were fabricated via a "coating and grafting" two-step film-forming technique on screen-printed platinum electrodes (SPPEs). Chemical composition, grafting density, equilibrium swelling, surface wettability, surface morphology, amperometric response, cyclic voltammograms, and other properties were evaluated for the modified SPPEs, successively. The modified SPPEs exhibited significant changes in their properties depending on the preparation concentrations, but all the resulting sensors showed excellent stability and repeatability. The modified sensors demonstrated favorable sensitivity to hydrogen peroxide and L-ascorbic acid. Furthermore, notable temperature-induced variations in electrical signals were observed as the electrodes were subjected to temperature fluctuations above and below the lower critical solution temperature (LCST). The ability to reversibly respond to temperature variations, coupled with the tunability of PNIPAM's thermoresponsive properties, opens up new possibilities for the design of sensors that can adapt to changing environments and optimize their performance accordingly.

Rapid and versatile, micro-patterning and functionalization of complex structures on ultra-thin and flexible polymeric substrates

Microscale patterning on flexible substrates is important in many applications such as in wearable sensors and microfluidics-based diagnostics, therefore low-cost fabrication methods which are scalable and amenable to mass production have attracted the interest of many companies and research groups. Dry film resists (DFRs) are commercially available materials with properties compatible with their implementation on flexible substrates to cover a wide range of applications, which also offer environmental and sustainability benefits due to the low waste generation compared to the liquid resists. However, there are limited detailed reports in the literature regarding the use of DFRs for the fabrication of microfluidic channels or other micropatterns (i.e., posts) on thin and flexible substrates. Herein we present in detail the fabrication of: a) microfluidic channels of width ranging from 50 μm up to 800 μm, and depth ranging from 30 μm up to 270 μm and b) square posts 80 μm × 80 μm in size and 30 μm in height. Particularly, our method enables the fabrication of ultra-deep microchannels (depth > 250 μm), highly ordered post arrays over large area (appr. 60 cm2), as well as complex designs with hierarchical scale features (80 μm posts inside 800 μm microchannels or micro-nanotexturing inside microchannels) on ultra-thin flexible substrates. To demonstrate the versatility of the method, three different DFRs were used on ultra-thin (30 μm), flexible, single-sided copper-clad polyimide substrates. It is also demonstrated that DFRs can be effectively modified using plasma etching to tune the surface wetting properties towards applications such as pumpless capillary action, where such functionality is required.

Long-chain alkyl groups enhance the water-repellent properties of short-chain perfluoroalkyl compounds: An experimental and computer simulation study

The polymers composed of long-chain stearyl acrylate (SA) and short-chain (perfluorohexyl) ethyl methacrylate (FA) were synthesized using the emulsion polymerization technique. Cotton fabric was then coated with these polymers to act as a water-repellent agent. Surface wetting properties of the coated cotton fabric were tested. In a peculiar manner, the water repellency of the coatings did not improve with the increase of the perfluorohexyl group. Therefore, the polymer's crystallization behaviors and melting temperature were assessed through differential scanning calorimetry (DSC) and computer simulation. A computer simulation was employed to analyze the density, surface energy, element distribution, chain arrangement, bond order parameter, and surface images of the polymer film. The results suggest that water repellency is not directly related to the film's surface energy but rather depends on the element proportion, bond angle distribution, and dihedral angle torsion energy. The key points will serve as invaluable indicators for the development of a highly efficient water-repellent coating with a low proportion of fluorine and provide a more sustainable solution for water-repellent applications.

Structural, Mechanical and Tribological Properties of Hydroxiapatite Reinforced Ti13Nb13Zr/HA Composite Produced by Friction Stir Process (FSP)

Many modification methods are applied to produce Ti-based biomedical materials. In this study, the structural, mechanical and tribological properties of unreinforced Ti13Nb13Zr alloy and Ti13Nb13Zr/HA composites with different contents of hydroxyapatite (HA) reinforcement were investigated by friction stir processing (FSP) to Ti13Nb13Zr alloy. SEM, FTIR and EDS analyzes were performed to determine the structural properties. Surface roughness values were determined using a 3D optical microscope. Surface wettability properties were investigated with a contact angle. Microhardness and wear test devices were used to determine the mechanical and tribological properties, respectively. Wear tests were carried out in a dry environment and phosphate buffered saline solution (PBS). The wear tracks were analyzed by SEM and 3D optical microscope. As a result of FTIR analysis, HA has PO43−, HPO42−, CO32− and OH− bonds. All samples exhibited hydrophilic surfaces suitable for cell adhesion. The FSP process increased the hardness and wear resistance of the Ti13Nb13Zr alloy in both atmospheres. In addition, Ti13Nb13Zr/HA composites significantly increased the hardness and wear resistance of Ti13Nb13Zr alloy and Ti13Nb13Zr alloy modified by FSP.

Enhancing surface morphology, mechanical, and wettability properties of PVA/chitosan/HAp nanofiber scaffold through dielectric barrier discharge plasma treatment

Dielectric barrier discharge (DBD) plasma treatment has been widely used for surface functionalization, allowing for precise modification of surface chemistry and morphology. This study investigates the efficacy of DBD plasma treatment in enhancing the surface morphology and wettability of electrospun nanofiber scaffolds composed of polyvinyl alcohol (PVA), chitosan, and hydroxyapatite (HAp), with potential applications in bone tissue engineering. Scanning electron microscopy (SEM) revealed significant alterations in surface morphology after treatment, including a reduction in average fiber diameter and the presence of uneven, damaged, and even broken fibers. Interestingly, the ultimate strength of the nanofibers increased from 1.13 ± 0.05 MPa to 6.99 ± 0.07 MPa despite the decrease in diameter. Contact angle measurements confirmed a remarkable improvement in wettability, with the contact angle decreasing from 39.46° to 7.45° following increasing treatment time. This enhanced wettability suggests improved cell adhesion, potentially leading to more effective bone tissue regeneration.

Stereolithography 3D printing of microgroove master moulds for topography-induced nerve guidance conduits

 Patients who have peripheral nerve damage from trauma or disease may suffer lifelong disability. Current interventions such as nerve allografts are inadequate due to limited availability of tissue and donor-site morbidity. Commercial nerve guidance conduits are used to bridge the damaged nerve gap and restore function. Typically, however, they lack cell-instructive guidance cues to promote directed regeneration. Tissue-engineered nerve guidance conduits that utilise micro- and nano-topographical architectures have been demonstrated to direct cell behaviour and contact guidance. This study uses projection micro-stereolithography-based three-dimensional (3D) printing to fabricate microgrooved (10–30 μm) master moulds to produce polydimethylsiloxane (PDMS) moulds and solvent cast polycaprolactone and polylactic acid films. The polymer microgrooves were successfully fabricated and were able to be formed into tubular nerve guidance conduits. The surface morphology, roughness, wettability, and thermal properties of the films were characterised. The microgroove topography improved proliferation and induced alignment of SH-SY5Y cells. This facile 3D printing approach is promising for the fabrication of nerve guidance conduits with topographical guidance cues as it obviates the need for using photolithographic techniques. Thus, this approach provides an alternative that is simpler, faster, cheaper, and offers greater design freedom.

Effect of time and voltage on the morphology of TiO2 films produced by anodization

This study investigates the influence of various anodic oxidation parameters on the photocatalytic activities of the nanostructured titanium dioxide (TiO2) films. TiO2 films were prepared by anodic oxidation of titanium substrate using 1 M Na2SO4 / 5 wt. % NH4F electrolyte, and then annealed at 500 °C. Anatase appears in all calcined samples. The anodic oxidation process was performed in two steps at different voltages (5–80 V) and times (15–480 min) to reveal the relationship between the surface morphologies, wettability and photocatalytic properties. The results showed that the voltage and anodization time can play important role in the surface morphology of nanostructured TiO2 films and thus in various properties. While 40 V showed the most efficient photocatalytic degradation among voltage values, 60 min was the most efficient time for photocatalytic degradation efficiency and lowest contact angle. In addition, a pore area fraction of 39.54%, equal diameter of 96.81 nm, and circularity of 66.7% were obtained from image analysis of the 60-min anodized sample. While increasing the voltage and time benefited up to a point in terms of photocatalytic efficiency, changes in morphology had a negative effect after a point. At low voltage and time values, small pore diameters result in low photocatalytic properties. This titania can be readily utilize to meet application expectations in areas such as gas sensors, photocatalysis and photovoltaic cells.

Enhancing biodegradable polymer surface wettability properties through atmospheric plasma treatmsurfaent and nanocellulose incorporation

This study investigates the effects of atmospheric plasma treatment on the surface properties of polylactic acid (PLA)/nanocrystalline cellulose (CNC) composites, aiming to improve their wettability and mechanical properties. The research utilizes a twin-screw extrusion process for fabricating PLA/CNC biocomposites, followed by surface modification using a custom-built, with a tenfold high-voltage atmospheric plasma system. The motivation of this treatment was to improved surface wettability and potential for enhanced adhesive bonding in ecological applications. These findings contribute to developing more sustainable composite materials by providing a method to improve the functionality of biodegradable polymers without compromising their environmental benefits.

Exploiting intermediate wetting on superhydrophobic surfaces for efficient icing prevention

HypothesisSuperhydrophobic surfaces can effectively prevent the freezing of supercooled droplets in technological systems. Droplets on superhydrophobic surfaces commonly not only wet the top asperities (Cassie State), but also partially penetrate into microstructure due to surface properties, environment, and droplet impact occurring in real-world applications. Implications on ice nucleation can be expected and are little explored. It remains elusive how anti-icing surfaces can be designed to exploit intermediate wetting phenomena. ExperimentsWe utilized engineered micro-/nanostructures, specifically micropillars, to modulate the wetting fraction in the microstructure. The behavior of intermediate wetting with supercooling and resulting implications on ice nucleation delay when potential nucleation sites are formed in the microcavities were investigated using experimental, theoretical, and simulation components. FindingsThe temperature-dependent wetting fraction in the microstructure increased at supercooled temperatures, partly activated by condensation in the microcavities. At −10/−20 °C, a critical wetting fraction led to maximum ice nucleation delays, with experimental results consistent with theoretical predictions. This critical wetting fraction minimized the effective contact area solid-to-liquid along the partially wetted microstructure. The study establishes physical relations between ice nucleation delays, geometrical surface parameters and wettability properties in the intermediate wetting regime, providing guidance for the design of ice resistant microstructured surfaces.

Mussel-inspired fabrication of fouling-resistant PPSU-based nanocomposite membrane using polydopamine and tannic acid-functionalized CeO2 nanoparticles towards effective oil-water emulsions separation

Surface modification of membranes using hydrophilic nanoparticles has proved promising to improve the surface wettability and antifouling properties of the membranes that are otherwise prone to the attachment of oil droplets. Nonetheless, the strong adhesion of nanoparticles onto the membrane surface and their long-term performance pose problems for their widespread application. To address these issues, a novel organic-inorganic hybrid coating was constructed onto surfaces of polyphenylsulfone (PPSU) ultrafiltration membrane via simultaneous deposition of mussel-inspired polydopamine (PDA) followed by immobilization of tannic-acid functionalized cerium oxide (CeO2) nanoparticles. These prepared membranes were characterized by FTIR, XPS, FESEM, EDX, pore size, water contact angle (WCA), underwater oil contact angle (UOCA), and separation performance. The effects of functionalization and nanoparticle concentration on membrane properties were investigated. SEM and EDX results showed that functionalized nanoparticles (up to optimum concentration: 0.05 wt%) were uniformly distributed onto the membrane surface, which exhibited increase in permeate flux (∼375 %), UOCA (∼36 %), Fouling resistance ratio (FRR ∼ 300 %) with a decrease in irreversible fouling (∼94 %) and WCA (∼80 %) and high oil rejection of > 99 % compared to pristine PPSU membrane. Long-term operation (for six cycles) indicates that the optimum membrane possessed high efficiency and durability for oil-in-water emulsion separation due to superb antifouling properties and strong binding of the functionalized nanoparticles onto the membrane surface.

Water Condensation in the Nanoscale Pores of Pt/C Catalyst Particles and Its Impact on Catalyst Utilization: A Simulation Based on a Reconstructed Structure from Nanoimaging.

In polymer electrolyte membrane fuel cells, carbon-supported platinum (Pt/C) catalyst particles require sufficient water condensation within the nanoscale pores to effectively utilize the interior Pt catalysts. Since experimental visualizations with nanoscale precision of this phenomenon are not yet possible, we utilized a Pt/C catalyst particle reconstructed from segmented nanoimaging of a catalyst powder, which served as the computational domain for lattice density functional theory (LDFT) simulation of water condensation. Paired with experimental water uptake data, LDFT successfully simulated high-resolution water condensation, capturing both thin-film and capillary water condensation phenomena. Using a simple proton movement method within the water network, we reproduced the Pt utilization data from a CO stripping experiment. Our findings highlight that at low relative humidity (RH), Pt utilization is influenced by thin water film formations, mainly dictated by the wettability properties of surfaces within primary pores and the Pt/C catalyst particle's exterior. Conversely, at high RH, Pt utilization is attributed to capillary water condensation in medium-to-large sized pores. This approach contributes a qualitative and quantitative discussion on hypotheses regarding the mechanism of Pt utilization, supporting recent studies (e.g., Girod, R.; Nat. Catal. 2023, 6, (5), 383-391).

Enhancement of Surface Properties Using Ultrashort-Pulsed-Laser Texturing: A Review

Surface texturing, which has recently garnered increased attention, involves modifying the surface texture of materials to enhance their tribology. Various methods have been developed for surface texturing. Laser surface texturing (LST) has attracted considerable interest because of its excellent texturing accuracy, controllability, and flexibility. It improves surface wettability properties and increases the wear resistance of materials while reducing the coefficient of friction. Herein, we present an overview of the underlying mechanisms of interactions between short-pulsed lasers and materials. In addition, we review published studies on the effects of LST on surface properties, including surface roughness, wettability, friction, and wear resistance. We believe that this review will provide valuable insights into the recent advances in surface property enhancement through LST, which exhibits potential for various applications.

Acid molecule-assisted high-quality SnO2 transport layer for perovskite solar cells

The SnO2 electron transport layer (ETL) serves a critical role in perovskite solar cells. However, the oxygen vacancy defects and excess hydroxyl (–OH) groups in SnO2 always lead to degradation of device performance. Herein, we introduce iminodiacetic acid (IDA) to modify the SnO2 ETL, yielding three key advantages: (1) IDA can neutralize excess –OH groups and passivate the defects in SnO2, diminishing the decomposition of perovskite layer; (2) the IDA-modified SnO2 exhibits superior electron conductivity and film quality, while providing improved energy level alignment with the perovskite layer; and (3) the IDA-modified SnO2 owns superior surface wetting properties that facilitates a more effective perovskite crystallization. Ultimately, the devices based on IDA-modified SnO2 obtain a champion efficiency of 24.02% and enhanced stability.

Sustainable fabric printing by using pre-consumed cellulosic textile wastes: The effect of waste particle content

The textile industry generates significant amounts of waste, including yarn/fiber fluffs, fabric scraps, offcuts, etc. These wastes can be recycled and repurposed for usage in screen printing which is a versatile and cost-effective printing technique by producing high-quality prints. In this study, pre-consumed colored cotton wastes were milled into 30–70 μm particle size by using a miller. Then the colored waste particles were included in a commercial printing paste and applied on cotton fabrics via screen printing. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, and energy dispersive spectrometer (EDS) were employed to observe the chemical changes in the printed textile fabrics. The printed fabrics were evaluated through color, wash/rub fastness, tensile strength, surface wettability, tactile, and air permeability properties. The dispersion quality of the waste particles on textile fabrics was observed by using light microscopy and scanning electron microscopy (SEM) images. The overall results demonstrate that a 10% amount of waste fibrous particle inclusion to the printing paste gave optimum results by means of dispersion quality of wastes, air permeability, and handle properties. Above 10% waste amounts, the waste particles cannot be dissipated well on the fabric surface, resulting in agglomerated and non-uniform printed areas. These findings hold substantial potential for promoting sustainable coloring applications by using colored pre-consumed textile wastes within the textile industry while maintaining high-quality fabric products.

Lattice Boltzmann simulations of quasi-steady film and axisymmetric nucleate boiling

An axisymmetric multiple relaxation time lattice Boltzmann method utilizing the Shan-Chen pseudo-potential model is developed and combined with an axisymmetric finite difference approximation of the energy equation to form a hybrid method with a view toward studying axisymmetric nucleate boiling. The mechanism of phase change in the Shan–Chen model is investigated, and the model is validated by simulating a Stefan problem as well as simulations of quasi-steady film boiling with comparisons to established results. Axisymmetric quasi-steady nucleate boiling is then investigated including examining the effect of the wetting properties of surfaces by varying the wettability force to vary the dynamic contact angle.