Surface Water Contact Angle Research Articles

Preparation of durable superhydrophobic composite surface

Surface durability deficit is the most serious challenge confronting superhydrophobic surfaces. The creation of durable superhydrophobic surfaces is therefore of significant importance. In this study, we etched the surface of 1060 aluminum alloy coated with polydimethylsiloxane and nano-fumed silica (PDMS&NF-SiO2) using an infrared nanosecond laser to yield a durable superhydrophobic hybrid surface (SHS). We characterized the composite surface’s static water contact angle (WCA), water roll-off angle (WSA), morphology, and composition using a contact angle meter, scanning electron microscope (SEM), three-dimensional profilometer, energy-dispersive spectrometer (EDS), and Fourier-transform infrared spectroscopy (FT-IR). We also conducted tests for the mechanical durability and thermal stability of the SHS surface using tape peeling, steel wool friction wear, blade scraping, sand impact, and heat treatment. Results indicated that the WCA and WSA of the SHS surface were 158.1° and 6.2°, respectively. The SHS surface maintained its superhydrophobic properties after withstanding at least 150 tape peeling tests, 100 steel wool friction wear tests, 50 blade scraping tests, and a 450 g sand impact test, demonstrating exceptional mechanical durability. The surface WCA and WSA of the SHS after a 30-hour heat treatment at 100 ℃−300 ℃ were 157.4° and 7.6°, respectively, demonstrating good thermal stability. We believe that this study's design and fabrication of superhydrophobic composite surfaces offer new insights for the preparation of wear-resistant and high-temperature resistant superhydrophobic surfaces.

Near-ultraviolet irradiation to stimulate unmodified polyether ether ketone to achieve stable and sustainable antibacterial activity

ObjectivesThis study aims to investigate the cytotoxicity and sustainable antibacterial activity of unmodified PEEK under specific wavelength light treatment (365 nm), and its antibacterial mechanism was also preliminarily discussed. MethodsA near-ultraviolet source with a wavelength of 365 nm and a power of 5 W were selected. The irradiation time was 30 min, and the distance was 100 mm. A water contact angle tester was used to characterize the surface of the PEEK after 1–15 light treatments. MC3TC-E1 cells were used to evaluate the cytotoxicity of the materials under light treatment. Five kinds of common oral bacteria were detected in vitro, and antibacterial efficiency was determined by colony-forming unit (CFU) and scanning electron microscope (SEM). The antibacterial mechanism of PEEK under light was preliminarily discussed by spectrophotometry. The membrane rupture of Staphylococcus aureus and Escherichia coli was detected by lactate dehydrogenase. Staphylococcus aureus and Staphylococcus mutans were selected for the cyclic antibacterial test. Statistical analysis was performed by one-way analysis of variance and Tukey multiple range test. A significance level of 0.05 was considered (α = 0.05). ResultsThe results of the cell experiment showed that PEEK had no cytotoxicity (P > 0.05). CFU results showed that PEEK had an obvious antibacterial effect on Staphylococcus aureus, Staphylococcus mutans, Staphylococcus gordonii and Staphylococcus sanguis, but had no antibacterial effect on Escherichia coli (P < 0.05). The SEM results also verified the above antibacterial effect. The existence of singlet oxygen was confirmed by spectrophotometry. Meanwhile, the rupture of Staphylococcus aureus membrane was verified by lactate dehydrogenase assay. The water contact angle of the PEEK surface did not change significantly after 15 cycles of light treatment. Cyclic antibacterial experiments showed that the antibacterial effect was sustainable. ConclusionsThis study showed that PEEK has good cytocompatibility with stable and sustainable antibacterial properties under near-ultraviolet. It provides a new idea to solve the non-antibacterial property of PEEK, and also provides a theoretical basis for its further application in dentistry.

Theoretical analysis of threshold pressure in tight porous media under stress

The threshold pressure is critical to characterizing multi-phase nonlinear flow through tight porous media under effective stress. Due to the complex and heterogeneous pore structures, the essential controls on the threshold pressure of tight porous media are not determined. In this study, based on the fractal theory, a theoretical model for the threshold pressure of gas–water two-phase flow through tight porous media is proposed. The derived model considers the effective stress, pore structures, gas–water capillary pressure, and boundary layer. The predicted threshold pressure from the developed model is in good agreement with the available experimental results, which validates the model. Moreover, based on the derived model, the effects of relevant parameters (e.g., gas–water surface tension, contact angle, initial porosity, and elastic modulus) on the threshold pressure are studied. Under a given effective stress, threshold pressure decreases as the initial porosity (or elastic modulus) increases. However, threshold pressure increases with the increase in gas–water surface tension (or contact angle). In addition, a positive relationship exists between threshold pressure and water saturation in tight porous media. From a practical standpoint, this model is of great significance in predicting threshold pressure and researching on the gas–water two-phase flow mechanism in tight sandstone gas reservoirs.

Improving the Hydrophobicity and Insulation Properties of Epoxy Resins by the Self-Assembly-Induced Coating of Fluorinated Graphene.

Moisture and insulation deterioration are important factors that cause the failure of epoxy packaging materials. Thus, improving the long-term stability of epoxy resins in a hot and humid environment is an important prerequisite for electronic components to adapt to complex working conditions and achieve high power densities. In this study, fluorinated graphene doped with hydroxy-terminated poly(dimethylsiloxane) was prepared and self-assembled into a micro/nanostructure on the surface of an epoxy resin, which effectively improved the surface hydrophobicity of the epoxy resin. In addition, the doping with hydroxy-terminated poly(dimethylsiloxane) modified the fluorinated graphene filler, thereby forming an arch bridge energy band structure inside the epoxy resin and thus regulating carrier migration. The water absorption of the epoxy resin decreased from 1.02 to 0.24%, and the surface water contact angle increased from 93.58 to 133.2°. Moreover, the electrical insulation performance of the modified epoxy resin was greatly improved when the surface resistivity and flashover voltage increased by 50.5 and 36.4%, respectively. Therefore, the proposed method realizes a simultaneous improvement in the hydrophobicity and insulation of epoxy resins.

Self-repairing and anti-fouling performance of anticorrosive coating in marine environment

Microcrack damage repair and microbial contamination prevention are two major challenges for anti-corrosion coatings on the surfaces of underwater installations. In this study, water-triggered self-healing microcapsules were combined with low-surface-energy fluoropolymers to prepare a bifunctional anti-corrosion coating with underwater self-healing and bio-fouling properties. The results showed that the prepared microcapsules had good mechanical, thermal, and environmental stability, with an average diameter of 153 μm and an encapsulation rate of 66.7%. When the microcapsule content in the coating was 8 wt%, the microcapsule dispersion performance and healing barrier effect of the composite coating were optimal, and the repair efficiency reached 81.6%. Furthermore, compared with the coating without microcapsules or graft fluoropolymers (PFG), the sample denoted as PFG18/4/IPDI-MC/ER showed the largest surface water contact angle and had the best protein inhibition rate of 87% when using bovine hemoglobin to detect the protein adsorption concentration on the coating surface.

Starch wall of urea: Facile starch modification to residue-free stable urea coating for sustained release and crop productivity

Quick leaching of urea fertilizer encourages different coatings, but achieving a stable coating without toxic linkers is still challenging. Here, the naturally abundant bio-polymer, i.e., starch, has been groomed to form a stable coating through phosphate modification and the support of eggshell nanoparticles (ESN) as a reinforcement agent. The ESN offers a calcium ion binding site for the phosphate to cause bio-mimetic folding. This coating retains hydrophilic ends in the core and gives an excellent hydrophobic surface (water contact angle 123°). Further, the phosphorylated starch+ESN led the coating to release only ∼30 % of the nutrient in the initial ten days and sustained for up to 60 days to show ∼90 % release. The stability of the coating has been attributed to its resistance to major soil factors viz., acidity and amylase degradation. The ESN also increases elasticity, cracking control, and self-repairing capacity by serving as buffer micro-bots. The coated urea enhanced the yield of rice grain by ∼10%.

Degradation of petroleum hydrocarbon pollutants by a superhydrophobic/superoleophilic microbial immobilized core-shell bioreactor

Efficient elimination of petroleum hydrocarbon pollution from the environments has received extensive attention due to its severe environmental hazards. Herein, we designed and fabricated a composite bioreactor capable of rapidly and selectively adsorbing petroleum hydrocarbons, specifically diesel, followed by microbial degradation to treat oily wastewater simply and efficiently. Briefly, the bioreactor was prepared using a three-dimensional superhydrophobic/superoleophilic stainless steel mesh as the shell and mixed microbial immobilized kapok fibers as core. By a simple surface modification, the surface water contact angle of the composite bioreactor reaches up to 155°. The high-speed camera's super lipophilic description enables most of the diesel oil to be absorbed within 21 ms. The porosity of the reactor's super hydrophilic kapok fibers aerogel can reach 89%. After immobilized mixed microorganisms, the number of microorganisms increased within 48 h in a favorable environment. The internal space of the reactor shows positive biocompatibility. Afterward, the experimental results of adsorption and degradation for diesel oil show that the degradation rate can reach more than 90% after 204 h, which is about 40% higher than that of the free mixed microorganisms. Compared with the simple method of embedding microorganisms in aerogel, a new core-shell structure microbial reactor is constructed in this paper, which can effectively avoid the risk of microbial leakage and achieve the goal of biodegradation while absorbing oily wastewater. It has constructed a more stable and effective protection space for the continuous degradation of oiling wastewater, while effectively protecting microorganisms from harsh environment, thus showing great potential in various applications such as eliminating organic pollution, oil removal, and wastewater purification.

Collective enhancement in hydrophobicity and electrical conductivity of gas diffusion layer and the electrochemical performance of PEMFCs

Gas diffusion layer (GDL) with optimized water management capacity facilitates the electrochemical performance of proton exchange membrane fuel cells (PEMFCs). However, the impact of hydrophobicity manipulation on the mass transport capacity of GDL makes it challenging to enhance the electrochemical performance of PEMFCs effectively. In this work, we proposed a facile strategy for collectively optimizing the hydrophobicity and electrical conductivity (EC) of GDL through the hydrothermal deposition followed by a high-temperature sintering process (HDS-GDL) Specifically, surface roughness of GDL and corresponding fiber diameter firstly increases after the hydrothermal deposition (HD-GDL) and then decreases after high-temperature sintering. Surface water contact angle of the HDS-GDL (133°) increases as compared to that of the Toray GDL (CR-GDL, 125°). Meanwhile, in-plane and through-plane ECs of HDS-GDL are simultaneously enhanced as compared to the CR-GDL. Moreover, HDS-GDL with collectively enhanced hydrophobicity and ECs further improve the electrochemical performance of PEMFCs. The polarization curve implies that enhancement of the power density at the Ohmic region under a wide cathode relative humidity (RH 0–80%) is mainly dominated by the optimized hydrophobicity. The findings in this work provide a new strategy for improving the electrochemical performance of PEMFCs by precisely tailoring the water management capacity of GDL.

Biofilm Formation on the Surfaces of CAD/CAM Dental Polymers.

Dental polymers are now available as monolithic materials which can be readily used in computer-aided design and computer-aided manufacturing (CAD/CAM) systems. Despite possessing numerous advantages over conventionally produced polymers, the polymers produced by either of these systems fail to exhibit immunity to surface microbial adhesion when introduced into the oral environment, leading to the development of oral diseases. The aim of this study was to analyze the biofilm formation of six microorganisms from the oral cavity and its correlation to the surface characteristics of CAD/CAM dental polymers. A total of ninety specimens were divided into three groups: resin-based composite, polymethyl methacrylate, and polyether ether ketone. The experimental procedure included surface roughness and water contact angle measurements, colony forming unit counting, and scanning electron microscopy analysis of biofilm formed on the surface of the tested materials. The data were analyzed using the Kruskal-Wallis test, with a Dunn's post hoc analysis, and one way analysis of variance, with a Tukey's post hoc test; the correlation between the measurements was tested using Spearman's correlation coefficient, and descriptive statistics were used to present the data. Despite using the same manufacturing procedure, as well as the identical manufacturer's finishing and polishing protocols, CAD/CAM dental polymers revealed significant differences in surface roughness and water contact angle, and the increased values of both parameters led to an increase in biofilm formation on the surface of the materials. The CAD/CAM resin-based composite showed the lowest number of adhered microorganisms compared to CAD/CAM polymethyl methacrylate and CAD/CAM polyether ether ketone.

Self-cleaning coatings for minimizing the impact of dust precipitation on the power production of solar cells utilizing mesoporous TiO2/SiO2 and ZnO/SiO2 films

The production of customized site-specific anti-soiling nanocoatings is needed for better utilization in dry parts of the world, with consideration of natural dust fallout in those regions. Kuwait's atmosphere carries airborne dust 70% of the year. Thus, designing anti-soiling nanocoatings for the arid region is necessary when dusty atmospheres are considered the norm. In this contribution, all solar cells were coated by SiO2, ZnO/SiO2, and TiO2/SiO2 films for self-cleaning applications and were tested in the summer period with the high level of dust and temperatures the current, voltage and power output was measured. We directly relate the coatings' performance to the electrical power output of the coated solar cells, which is considered among the few studies in this field. Influences of properties ZnO/SiO2 and TiO2/SiO2 films, such as the surface morphology, transparency, and water contact angles on the power production efficiency of solar cells, were systematically investigated. The three fabricated films showed a contact angle of about 70o agrees with the expected hydrophilicity behaviour. The thickness values of SiO2, TiO2/SiO2 and ZnO/SiO2 films were found to be ∼35, 205 and 240, respectively. Transmission values of the synthesized SiO2, TiO2/SiO2 and ZnO/SiO2 films were determined at about 97.95, 96.62 and 96.25%, respectively, suggesting that all synthesized films are highly transparent over the visible range. Solar cell samples were subjected to natural conditions for 30 days in the summer. The results indicated that the effect of dust on the power production efficiency for ZnO/SiO2 and TiO2/SiO2 coated PV cells was lower than the solar cells coated with SiO2 film concluded from the low power output of 0.16 Watt for this coating compared to 0.18 and 0.2 Watts for the other two coatings. The mesoporous ZnO/SiO2 and TiO2/SiO2 films not only significantly minimized the accumulation of dust on the PV cells but also boosted the power-generating efficiency. The average daily power output of around 0.2 Watt and the deviation values of the soiling ratios of about 5% showed that TiO2/SiO2 film was a durable coating against dust for the presented experiment time, while the ZnO/SiO2 film started as good, but showed deterioration after six days of the experiment with a deviation in SR value reached 15%. The TiO2/SiO2 nanocoating showed consistent behaviour with lower deviations for soiling ratio (SR) values and constant average power output for the solar cells concluding good durability in solar cells tests during harsh conditions in the summer, implying the excellent service life of solar cells.

Schiff base cross-linked dialdehyde β-cyclodextrin/gelatin-carrageenan active packaging film for the application of carvacrol on ready-to-eat foods

The construction of films has often been devoted to loading active substances to improve biological activity in recent years. However, the positive impacts on packaging properties by establishing a cross-linking reaction between the load materials and the substrate are frequently overlooked. The essence of this work was to cross-linked gelatin-based film with κ-carrageenan and dialdehyde β-cyclodextrin inclusion (IC/DA-β-CD) and the functionalities were also investigated. β-cyclodextrin was oxidized with sodium periodate to introduce aldehyde groups. The hydrophobic cavity was not disrupted and the modified cyclodextrin exhibited solubilization of carvacrol. In addition, the introduction of aldehyde group improved the dispersion effect of cyclodextrin in water, but the solid particles were more likely to gather when exposed to the air. Electrostatic complexation of gelatin and κ-carrageenan significantly (p < 0.05) enhanced the tensile strength (from 10.85 to 26.54 MPa), surface water contact angle (WCA) from 97.16 to 110.08° and thermal stability of the film. Contrarily, the elongation at break rate decreased significantly and the antibacterial activity was not potent. The crosslinked IC/DA-β-CD further improved the mechanical properties, and excellent barrier capabilities of the film. Consequently, the WCA and thermal stability were further enhanced as well as the antioxidant capacity and antibacterial activity against Listeria monocytogenes (the eradication rate reached 99.989%). Release experiments demonstrated cross-linked film was more suitable for fatty foods with excellent packaging application ability for ready-to-eat (RTE) ham. Based on the promising properties, the cross-linked film has great deal of potential as RTE active packaging.

Hierarchically Structured Nanoparticle-Free Omniphobic Membrane for High-Performance Membrane Distillation.

The functional loss of membranes caused by pore wetting, mineral scaling, or structural instability is a critical challenge in membrane distillation (MD), which primarily hinders its practical applications. Herein, we propose a novel and facile strategy to fabricate omniphobic membranes with exceptionally robust MD performance. Specifically, a substrate with a hierarchical re-entrant architecture was constructed via spray-water-assisted non-solvent-induced phase separation (SWNIPS), followed by a direct fluorinated surface decoration via "thiol-ene" click chemistry. Deionized (DI) water contact angle measurements revealed an ultrahigh surface water contact angle (166.8 ± 1.8°) and an ultralow sliding angle (3.6 ± 1.1°) of the resultant membrane. Destructive abrasion cycle and ultrasonication tests confirmed its structural robustness. Moreover, the membrane possessed excellent wetting resistance, as evidenced by the prevention of membrane pore penetration by all low-surface-tension testing liquids, allowing stable long-term MD operation to treat brine wastewater with a surfactant content of 0.6 mM. In a desalination experiment using shale gas wastewater, the omniphobic membrane exhibited robust MD performance, achieving a high water recovery ratio of ∼60% without apparent changes in water flux and permeate conductivity over the entire membrane process. Overall, our study paves the way for a nanoparticle-free methodology for the scalable fabrication of high-performance MD membranes with surface omniphobicity and structural robustness in hypersaline wastewater treatment.

Wetting and aging behaviors for several O2 and NH3 plasma treated nanofibrous and flat film polymer materials: A comparison

AbstractAging (or “hydrophobic recovery”) of plasma‐modified polymer surfaces has been known and documented in the literature over several decades; to the best of our knowledge, the present study appears to be the first in which this is done for two vastly different rough surface structures: (i) electrospun nanofibrous (NF) mats, and (ii) flat films (FF), for three polymers of well‐documented interest in biotechnological applications: poly(lactic acid); poly(urethane); and poly(caprolactone). Two different plasma treatments are applied: low‐pressure (LP) radio‐frequency (rf) glow discharges in flows of O2 and NH3 under mild power conditions. Measured time‐dependent surface compositions (from X‐ray photoelectron spectroscopy survey spectra) and water contact angles (WCA) were found to tend toward asymptotic limiting values after ca. 30 days of storage in clean air, as previously reported by these and other authors. An entirely novel aspect of this work is to examine and compare time‐dependent WCA behaviors of NF and FF samples in terms of Wenzel (W) and Cassie‐Baxter (C‐B) model behaviors, including possible transitions from C‐B to W and their interpretation.

Enhanced Tensile Properties, Biostability, and Biocompatibility of Siloxane-Cross-Linked Polyurethane Containing Ordered Hard Segments for Durable Implant Application.

This work developed a series of siloxane-modified polyurethane (PU-Si) containing ordered hard segments by a facile method. The polyaddition between poly(ε-caprolactone) and excess diurethane diisocyanate was carried out to synthesize a polyurethane prepolymer with terminal isocyanate groups, which was then end-capped by 3-aminopropyl triethoxysilane to produce alkoxysilane-terminated polyurethane; the target products of PU-Si were obtained with hydrolysis and the condensation of alkoxysilane groups. The chemical structures were confirmed by FT-IR and XPS, and the effect of the siloxane content or cross-linked degree on the physicochemical properties of the PU-Si films was investigated in detail. The formation of the network structure linked by Si-O-Si bonds and interchain denser hydrogen bonds endowed PU-Si films with fine phase compatibility, low crystallinity, high thermal stability, and excellent tensile properties. Due to the high cross-linked degree and low interfacial energy, the films displayed a high surface water contact angle and low equilibrium water absorption, which resulted in slow hydrolytic degradation rates. Furthermore, the evaluation of protein adsorption and platelet adhesion on the PU-Si film surface presented high resistance to biofouling, indicating superior surface biocompatibility. Consequently, the siloxane-cross-linked polyurethane, which possessed excellent tensile properties, high biostability, and superior biocompatibility, showed great potential to be explored as biomaterials for durable implants.

The Effects of Solvent on Superhydrophobic Polyurethane Coating Incorporated with Hydrophilic SiO2 Nanoparticles as Antifouling Paint

Polyurethane (PU) paint with a hydrophobic surface can be easily fouled. In this study, hydrophilic silica nanoparticles and hydrophobic silane were used to modify the surface hydrophobicity that affects the fouling properties of PU paint. Blending silica nanoparticles followed by silane modification only resulted in a slight change in surface morphology and water contact angle. However, the fouling test using kaolinite slurry containing dye showed discouraging results when perfluorooctyltriethoxy silane was used to modify the PU coating blended with silica. The fouled area of this coating increased to 98.80%, compared to the unmodified PU coating, with a fouled area of 30.42%. Although the PU coating blended with silica nanoparticles did not show a significant change in surface morphology and water contact angle without silane modification, the fouled area was reduced to 3.37%. Surface chemistry could be the significant factor that affects the antifouling properties of PU coating. PU coatings were also coated with silica nanoparticles dispersed in different solvents using the dual-layer coating method. The surface roughness was significantly improved by spray-coated silica nanoparticles on PU coatings. The ethanol solvent increased the surface hydrophilicity significantly, and a water contact angle of 18.04° was attained. Both tetrahydrofuran (THF) and paint thinner allowed the adhesion of silica nanoparticles on PU coatings sufficiently, but the excellent solubility of PU in THF caused the embedment of silica nanoparticles. The surface roughness of the PU coating modified using silica nanoparticles in THF was lower than the PU coating modified using silica nanoparticles in paint thinner. The latter coating not only attained a superhydrophobic surface with a water contact angle of 152.71°, but also achieved an antifouling surface with a fouled area as low as 0.06%.

Dispersive adsorption and anticorrosion properties of natural capsaicin on Q235 steel in mixed H2SO4 and NaCl environment: Characterization, experimental and theoretical studies

Although traditional corrosion inhibitors have demonstrated immense relevance in metal protection for many years now, issues relating to their moderate to high toxicities, non-biodegradability, and cost-effectiveness have persisted. For these reasons, bio-based corrosion inhibitors are gathering significant research attention and have shown great potentials in the corrosion suppression of metals while being relatively cheap and eco-friendly. This study focuses on the anticorrosion and adsorption properties of natural capsaicin isolated from Capsicum annuum L. as a bio-based corrosion inhibitor for Q235 steel in a mixed acid and chloride system (0.25 M H2SO4 + 0.5 M NaCl). FTIR and NMR techniques afforded the characterization and identification of the phytocompound. Electrochemical and gravimetric measurements were employed for anticorrosion evaluations. 3D surface profilometer, SEM, and water contact angle examinations provided adsorption proof for capsaicin on steel surface. XPS provided insights into the corrosion suppression mechanism of capsaicin. Computational techniques allowed the description of the adsorption characteristics, molecular interactions, molecular orientations and binding energies of capsaicin on steel substrate. Having a maximum inhibition performance of 94.8% at 298 K, capsaicin was classified as a functional mixed-type corrosion inhibitor that is reliant on concentration and surrounding temperature for its effectiveness. While also validating the results from water contact angle measurements, 3D profiling, and SEM, XPS results disclosed that the interactions of capsaicin with steel surface leading to its adsorption and anticorrosion effect involved both physisorption and chemisorption processes, and this was in perfect correlation with the Langmuir monolayer adsorption model.

Structural, physical, wear and anticorrosive properties of electroactive polyamide/Ti3C2Tx MXene nanocomposite

The 2D few-layered Ti3C2Tx MXene nanosheets have been prepared by etching and delamination of aluminium layers from the Ti3AlC2 MAX phase. The electroactive polyamide (EPA)/Ti3C2Tx MXene nanocomposites (NCs) containing (0.6, 1.2 and 1.8 wt%) MXene were prepared via in-situ oxidative coupling polymerization. The structural properties of NCs indicated close interaction between EPA and MXene resulting in improvement in physical properties such as electrical conductivity, thermal stability and adhesion strength. The surface roughness and water contact angle were not affected by the addition of Ti3C2Tx MXene in the EPA matrix. The tribological properties were improved for NCs coated samples. The corrosion study revealed the excellent corrosion protection ability of EPA/Ti3C2Tx MXene NCs containing 1.2 wt% MXene.

Fabrication and Characterization of Carbon Nanotube Filled PDMS Hybrid Membranes for Enhanced Ethanol Recovery.

Ethanol separation via the pervaporation process has shown growing application potential in solvent recovery and the bioethanol industry. In the continuous pervaporation process, polymeric membranes such as hydrophobic polydimethylsiloxane (PDMS) have been developed to enrich/separate ethanol from dilute aqueous solutions. However, its practical application remains largely limited due to the relatively low separation efficiency, especially in selectivity. In view of this, hydrophobic carbon nanotube (CNT) filled PDMS mixed matrix membranes (MMMs) aimed at high-efficiency ethanol recovery were fabricated in this work. The filler K-MWCNTs was prepared by functionalizing MWCNT-NH2 with epoxy-containing silane coupling agent (KH560) to improve the affinity between fillers and PDMS matrix. With K-MWCNT loading increased from 1 wt % to 10 wt %, membranes showed higher surface roughness and water contact angle was improved from 115° to 130°. The swelling degree of K-MWCNT/PDMS MMMs (2 wt %) in water were also reduced from 10 wt % to 2.5 wt %. Pervaporation performance for K-MWCNT/PDMS MMMs under varied feed concentrations and temperatures were evaluated. The results supported that the K-MWCNT/PDMS MMMs at 2 wt % K-MWCNT loading showed the optimum separation performance (compared with pure PDMS membranes), with the separation factor improved from 9.1 to 10.4, and the permeate flux increased by 50% (40-60 °C, at 6 wt % feed ethanol concentration). This work provides a promising method for preparing a PDMS composite with both high permeate flux and selectivity, which showed great potential for bioethanol production and alcohol separation in industry.

Ce-MOF-based superhydrophobic polyurethane sponge reinforced by cellulose for efficient oil-water separation

It is extremely significant to manufacture materials with simple and low-cost synthetic method for the disposal of large-scale oil spills and environmental pollution caused by the illegal discharge of oily wastewater. In this paper, cerium metal-organic framework (Ce-MOF), 1H, 1H, 2H, 2H perfluorodecyltrimethoxysilane (PFOTS) and cellulose were used as raw materials to prepare polyurethane hydrophobic sponges (PU) interconnected by chemical bonds to improve physical properties performance. The sponge shows excellent superhydrophobicity with a surface water contact angle (WCA) of 152.53 ± 0.8°. It has high mechanical strength and oil absorption capacity for various oils/organic solvents up to 15.0–44.9 times its weight. It is more imortant that C–F–Ce@PU can separate immiscible oil-water mixtures driven by vacuum pump or gravity. Superhydrophobic/oleophilic C–F–Ce@PU can also be used to separate water-in-oil emulsions. The above characteristics provide a reference for its practical application in oil-water separation.

Influence of the Maillard Reaction on Properties of Air-Assisted Electrospun Gelatin/Zein/Glucose Nanofibers.

To develop biodegradable, sustainable, and environment-friendly functional food-packaging materials, gelatin/zein/glucose nanofibers were fabricated through air-assisted electrospinning and then crosslinked by the Maillard reaction under mild conditions (60 °C and 50% relative humidity) in this study. Compared to traditional electrospinning, air-assisted electrospinning increased the yield of nanofibers by 10 times, and the average diameter from 263 nm to 664 nm, while the airflow facilitated uniform and smooth nanofiber formation. During the Maillard reaction in 0-5 days, the gelatin/zein/glucose showed no morphology change. Fourier transform infrared spectra analysis indicated that gelatin interacted with zein through hydrogen bonding and the occurrence of the Maillard reaction among the protein and glucose molecules. After four days of Maillard reaction, the nanofibers presented higher thermal stability, the most hydrophobic surface (water contact angle: 133.6°), and stiffer network structure (elastic modulus of 38.63 MPa, tensile strength of 0.85 MPa). Overall, Maillard-reaction-crosslinked gelatin/zein/glucose nanofibers showed favorable physical properties, which suggests their potential for application in food-active packaging.