High Water Contact Angle Research Articles

Enhancing cherry tomato packaging: Evaluation of physicochemical, mechanical, and antibacterial properties in tannic acid and gallic acid crosslinked cellulose/chitosan blend films

The aim of this work was to study the characteristics of composites fabricated from cellulose (CL) and chitosan (CS) blends that were reinforced with different tannic acid (TA) and gallic acid (GA) concentrations. The structure and antibacterial activity of CL/CS composite films were investigated with the addition of TA and GA. The composite films were subjected to mechanical, water contact angle (WCA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), and antibacterial activity tests. The FTIR results and the uniform dense SEM images confirmed the interaction of TA and GA with the CL/CS blends. The water vapor transmission rate (WVTR) of films with 5 wt% TA and GA improved by 23.02 %. The tensile strength of the CCTA-3 film was 27.67 MPa, demonstrating higher tensile properties compared to films made from CL and CS blend film (13.20 MPa). The prepared films also showed increased resistance to moisture and water, as indicated by their higher water contact angle (WCA) values (59.43°). The antibacterial activity of the films was effective against food-borne bacteria such as S. aureus and E. coli due to the addition of TA and GA. The shelf-life of cherry tomatoes increased by approximately 15 days when covered in CCTA-3 instead of polyethylene film. Based on the results, CL/CS blend films containing TA could be beneficial for use in active food packaging.

Increasing hydrophobicity of ceramic membranes by post-deposition nitrogen annealing of molecular layer deposition grown hybrid layers

Molecular layer deposition is increasingly used to functionalize the surface of planar and 3D porous substrates. This study explores functionalized ‘alucone’ hybrid layers grown on ceramic substrates to enhance their surface hydrophobicity. The layers were made from trimethyl-aluminum as a precursor with five different alcohols as a co-reactant: aliphatic (ethane-1,2-diol, 2,2-oxydiethanol, 1,6-hexanediol), and aromatic (4-aminophenol, benzene-1,4-diol). After post-deposition annealing in N2 atmosphere at 250 and 350 °C, the changes in the physical properties and the chemical affinity of the layers were studied and compared to those of the as-deposited hybrid layers. Differential thermal analysis of the hybrid layers showed higher decomposition temperatures forthe layers grown from aromatic alcohols than for those grown from aliphatic alcohols. Additionally, Fourier-transform infrared and X-ray photoelectron spectroscopy showed that an increase in annealing temperature decreased the concentrations of surface hydroxyl-groups and caused changes in the carbon-related groups. These results could be correlated to the hydrophobicity of the layers: higher water contact angles (>90°) were measured for annealed samples, compared to those (<90°) of the as-deposited samples grown at 150 °C. These findings confirm that the proposed method of MLD functionalization and post-deposition annealing can be used to tune the surface hydrophobicity of ceramic membranes.

Wood Surface-Embedding of Functional Monodisperse SiO2 Microspheres for Achieving Robust, Durable, Nature-Inspired, Programmable Superrepellent Interfaces.

Nature-inspired, robust, durable, liquid-repellent interfaces have attracted considerable interest in the field of wood biomimetic intelligence science and technology application. However, realizing green environmental protection and low maintenance and replacement cost wood surfaces constructed with micro/nanoarchitectures is not an easy task. Aiming at the problem of poor waterproof performance of wood, a silicon dioxide/polydimethylsiloxane (SiO2/PDMS) self-cleaning programmable superhydrophobic coating was biomimetically constructed on the wood substrate by surface-embedded dual-dipping design based on the "substrates + nanoparticles" hybrid principle of the lotus leaf effect. This robust, durable, nature-inspired, self-cleaning, programmable superhydrophobic coating was found to have no observable impact on the original color and texture of the natural wood. The SiO2/PDMS/wood prepared exhibited exceptional liquid repellency and a high static water contact angle (WCA) of 158.5° and a low slide angle (SA) of 10°, including everyday general-purpose droplets, indicating that the introduction of the monodisperse SiO2 microspheres can effectively enhance the superhydrophobic properties of the hydrophilic wood. We applied this strategy to a variety of substrates, including wood-cellulose aerogel and wood-cellulose paper, and demonstrated that the liquid-repellent nature of the self-cleaning superhydrophobic coating remained unchanged. Moreover, the superhydrophobic surface of SiO2/PDMS/wood was preserved even after harsh abrasion conditions, including mechanical damage (sandpaper, sharp steel blade, and tapes), thermal damage (UV irradiation and low/high-temperature exposure such as steaming and freezing), chemical damage, and solvent corrosion (immersion in acid, alkali), demonstrating robust stability of the superhydrophobic coating. Furthermore, the SiO2/PDMS programmable superhydrophobic coating exhibits exceptional exciting self-cleaning and stain-resistant properties, making it offer greater possibilities in terms of scientific challenges and real-world problem-solving at biomimetic smart superhydrophobic interfaces in wood.

The preparation of fish scale gelatin-polydopamine photothermal sterilization film and its application for storage of cherry tomato

In this study, polydopamine nanoparticles (PDA NPs) were synthesized and fish scale gelatin (FSG) was extracted by hot water hydrolysis. The film for photothermal sterilization was created by casting FSG with the addition of PDA NPs. The results indicated that the PDA NPs were able to heat up to 46 °C in 5 min under near-infrared (NIR), demonstrating good photothermal conversion. The PDA NPs/FSG solution showed short-term bactericidal activity against Staphylococcus aureus and Escherichia coli, with a bactericidal rate of more than 99 %. The PDA NPs/FSG film could warm up to 42.6 °C under NIR irradiation for 5 min. With the addition of 0.3 % of PDA NPs, the PDA NPs/FSG films showed high UV absorption, DPPH and ABTS radical scavenging ability, and high water contact angle (WCA), improving the barrier to water and oxygen and the tensile strength. The 0.3 % PDA NPs/FSG film triggered by NIR effectively maintained the firmness, soluble solids content and appearance, and delayed the weight loss of cherry tomatoes. Thus, the PDA NPs/FSG films had good photothermal antimicrobial activity and could be used for extending the shelf life of cherry tomatoes.

A novel ultra-light bio-based fiberboard from mexican feather grass for thermal and acoustic insulation in green building construction applications

The use of natural fibers as raw materials for insulation fiberboard production is emerging as a strategy to replace wood fibers. This study developed an ultralightweight natural fiber insulation core fiberboard (CFB) with high mechanical strength, hygroscopic resistance, and excellent acoustic and thermal insulation properties. This study examined the production of CFB, which utilizes Mexican feather grass fibers with an epoxy resin binder across a range of densities of 0.18–0.36 g∙cm−3. Furthermore, the impact of incorporating a reinforcing skin layer of woven glass fibers on the core fiberboard's physical, mechanical, acoustic, and thermal properties was evaluated. All the fiberboard samples exhibited excellent thermal conductivity values (0.048–0.057 W/mK), which increased with increasing panel density (0.18–0.36 g∙cm−3). In addition, all of them displayed superior mechanical properties following the ASTM C208 standard. In terms of climatic resistance of the fiberboards, the results displayed excellent water resistance, exhibiting minimal humidity content (<5 %), thickness swelling (<6.5 %), and a hydrophobic surface, as indicated by the high-water contact angle (>121.96 at 30 s). Sound reduction exhibited a frequency-dependent tendency, with denser and sandwich fiberboards showing greater sound reduction of up to 27.9–36.56 dB at 3150 Hz for CFB-0.36 and SFB-0.52, respectively. Following ASTM C208, both core fiberboards and those coated with woven glass fiber skins (sandwich fiberboards, SFB) met the thermomechanical property requirements for regular and structural wall sheathing applications, respectively. These findings highlight the potential of Mexican feather grass as a bio-based alternative to wood, enabling the production of eco-friendly ultralightweight fiberboards with excellent thermomechanical properties suitable for building construction, such as regular and structural wall sheathing applications and ceiling decorations.

Design strategy of super tough hydrophobic bamboo framework composites with internal network entanglement reinforcing structure

The low strength and high hygroscopicity of natural bamboo limit its use in structural building materials. Herein, lignin and hemicellulose were partially removed from natural bamboo in order to create bamboo frameworks featuring well-aligned bamboo fibers. Subsequently, these bamboo frameworks (BF) are infused with epoxy resin (EP) modified with PDMS and subjected to hot-pressing to fabricate bamboo-epoxy composites (PDMS-EP/BF). The incorporation of flexible PDMS chains facilitated intermolecular chain entanglement, which inhibited crack propagation and improved the bonding between bamboo and EP. The findings of the research indicated that the PDMS-EP/BF composites exhibited a significant enhancement in flexural strength by 98%, modulus of elasticity by 129%, toughness by 399%, and tensile strength by 177% when compared to natural bamboo. Additionally, the modification led to a decrease in the surface energy of the composites, resulting in increased hydrostatic contact angle and imparting water repellency to the material. Compared to natural bamboo, PDMS-EP/BF has 309% higher water contact angle and 143% lower surface energy. In addition, large composites have been prepared and their interface strength was tested. The findings of the study offer insights into the potential enhancement of bamboo composites to achieve increased flexural strength, modulus, and toughness. This could expand the utilization and significance of bamboo in the realm of construction materials.

Preparation and performance of hydrophobic two-component polyurethane clearcoats based on perfluoro alcohol modified polyisocyanate hardener

In this study, three perfluoro alcohol with different fluoroalkyl chain length, i.e., 3,3,3-trifluoro-1-propanol (TEOH1), 2-perfluorobutyl ethanol (TEOH4), 2-perfluorohexyl ethanol (TEOH6), were first reacted with polyisocyanate to get hardeners bearing various contents and lengths of fluoroalkyl chain. The fluorinated polyisocyanate hardener was then adopted to fabricate hydrophobic two-component polyurethane (2K PU) clearcoats. The highest water contact angles (WCAs) of the hydrophobic 2K PU clearcoats with no haze and non-sticky surface are 91.9°, 101.6° and 106°, achieved at the perfluoro alcohol dosage of 10 %, 20 % and 20 % for TEOH1, TEOH4 and TEOH6, respectively. Accelerated weathering and outdoor exposure tests were adopted to examine the hydrophobicity durability of the perfluoro alcohol-modified coatings, and dirt pick-up resistance (DPUR) outdoors was also monitored. All coatings showed decreased WCAs in weathering tests. Nevertheless, WCAs of coatings with ≥20 % TEOH4 and ≥5 % TEOH6 remained hydrophobicity after 228-day outdoor exposure. Loss of hydrophobicity is attributed to the oxidation of PU matrix, removal of free perfluoro alcohol-modified polyisocyanate and embedding of silicate dirt. Improved DPUR of 2K PU clearcoat was demonstrated outdoors after incorporation of perfluoro alcohol, especially for the cases with TEOH4 and TEOH6 under an adequate dosage. As a whole, longer fluoroalkyl chain favors the acquisition of both higher hydrophobicity, better hydrophobicity durability, and better outdoor DPUR.

Synthesis, characterization, and application of films made from highly substituted N-perfluoroacylated chitosan

Highly substituted perfluoroacylated chitosan can alter the physicochemical properties of chitosan; however, the currently synthesized perfluoroacylated chitosan has a low degree of substitution. In this study, we present a simple method for the homogeneous preparation of highly substituted N-perfluoroacylated chitosan, conducted at room temperature without requiring strict anhydrous or oxygen-free conditions. Various perfluorocarbon chains were successfully attached to chitosan through a reaction between perfluorinated acid esters and amines, catalyzed by DBU. The synthesized N-perfluoroacylated chitosan, with high degree of substitution, demonstrated excellent solubility in common organic solvents. Comprehensive characterization was performed using elemental analysis, nuclear magnetic resonance (including two-dimensional NMR), gel permeation chromatography, infrared spectroscopy, X-ray diffraction, and thermal analysis. The resulting films exhibited high water contact angles. Notably, as the fluorocarbon chain length increased, tensile strength gradually decreased, while elongation at break improved. Additionally, water uptake, water vapor transmission rate, and oxygen transmission rate all exhibited a declining trend. The films exhibited good biocompatibility, and in the grape preservation experiment, HFBC treatment effectively delayed grape aging and deterioration while enhancing quality preservation. These results suggest that HFBC film holds promising potential for food packaging applications.

Enhanced hydrophobicity of polyurethane coating for steel protection through replication and nanomaterial integration

Polyurethanes (PU) are widely used in corrosion protection, anti-biofouling coatings, and self-cleaning glass, yet their low hydrophobicity poses durability challenges. This study addresses this by enhancing PU coatings’ hydrophobicity by refining surface roughness and forming tailored porous structures. Using drop, spin, dip, and spray coating techniques, hydrophobic PU coatings were fabricated on 304 steel plates. To further enhance hydrophobicity, 0.5 w/v% graphene nanoplatelets (GNP) were introduced into the coatings. Additionally, stainless-steel 500 mesh was incorporated to create patterned surfaces, increasing surface roughness and tailoring the porous structure. The analysis included optical and scanning electron microscopy, water contact angle (WCA) measurements, Fourier transform infrared spectroscopy, electrochemical corrosion tests, and atomic force microscopy. Incorporating GNP notably increased WCA by 20–23° and reduced corrosion rates in a 3.5% NaCl solution. Likewise, applying stainless-steel mesh improved surface roughness, raising WCA by 3-8° and decreasing corrosion rates. The study observed changes in porous structure, with pore size reduction correlating with increased roughness and decreased corrosion rates upon mesh application and GNP addition. This comprehensive examination highlights the potential of PU coatings for various applications and underlines the importance of tailored porous structures in enhancing their performance and versatility. Spin coating emerged as the optimal technique, yielding uniform, defect-free coatings with the highest WCA.

Construction of a hydrophobicity, phosphorus‐ and nitrogen‐containing layered double hydroxides‐based synergistic effect flame retardant for poly (lactic acid)

AbstractIn this work, a synergistic effect strategy was explored for fabricating hydrophobicity, phosphorus‐ and nitrogen‐containing layered double hydroxides nanosheets (LDHs) based flame retardant (LDHs‐K@DM). This fabricating process was achieved by amination of the surface of LDHs and, subsequently, interfacial self‐assembly with high P content of diethylenetriaminpenta (methylene‐phosphonic acid) (DTPMP) and high N content of melamine (MEL). The chemical construction and thermal stabilization properties of LDHs‐K@DM were confirmed via different characterization approaches. The results revealed that LDHs‐K@DM was successfully prepared and the surface of LDHs‐K@DM was transformed into hydrophobicity with high water contact angle. Moreover, LDHs‐K@DM had better thermal stability. After that, LDHs‐K@DM was molten compounded with biobased polylactic acid (PLA). It was suggested that LDHs‐K@DM were uniformly dispersed in the PLA matrix and could accelerate the decomposition of PLA to form char residues. Most importantly, the addition of 20 wt% LDHs‐K@DM into PLA can endow the composite to achieve a desirable UL‐94 V‐0 rating and the limiting oxygen index value of 30.9%. Finally, the synergistic effect flame retardant mechanism of LDHs‐K@DM was comprehensively analyzed. This synergistic decorating strategy for preparing LDHs‐K@DM flame retardant is promising for industrial production.

Eco-friendly covalently connected silicone hydrogel with negatively charged surface for marine anti-biofouling

In this study, a silicone hydrogel (Gel-TA-Si-x) with amphiphilic and negatively charged surfaces was prepared by combining low surface free energy silicone with highly hydrophilic hydrogel materials using the method of one-step solvent-free bulk polymerization. The hydrogel films exhibited good mechanical properties. This was primarily reflected in the high tensile strength (1 MPa) and elongation at break (358.1 %). Notably, the film exhibited increased hydrophobicity, higher water contact angle and gradual decline in water absorption rate as the mPDMS monomer dosage increased. Despite this, the surface free energy remained low at 22.1 mJ m−2, indicating effective fouling release capability (removal strength against pseudobarnacles was 0.16 MPa). In addition, the surface zeta potential of the hydrogel was as low as −86 mV (at pH = 10). Laboratory antifouling performance tests indicated that the surface negativity of the material enhanced its static antifouling performance and the hydrogel with a negatively charged surface exhibited high bacterial adhesion resistance of 93 % and good resistance to Chlorella adherence and biofilm inhibition. Favorable anti-fouling performance was observed after 180 d of marine field testing. Moreover, the covalent connection of silicone monomers with hydrogel monomers through copolymerization create a stable three-dimension crosslinking network, thereby improving the durability of materials in complex marine environments. This study provides a new idea for developing efficient and environmentally friendly silicone hydrogel antifouling materials.

Simple fabrication of breathable poly (vinylidene fluoride) fibrous membranes decorated by silica nanoparticles with enhanced waterproof property

In recent years, scientists have undertaken various preparation approaches to improve the waterproof and moisture permeability of fiber membranes, among which electrospinning has emerged as the simplest and most effective one. In this paper, poly (vinylidene fluoride)/silica (PVDF/SiO2) fibrous membranes were prepared by one-step electrospinning combined with heat treatment. The morphology, surface wettability, water resistance and moisture permeability of the fibrous membranes were also characterized. When the concentration of PVDF was 12 wt%, the nanofiber membranes exhibited the most uniform and optimal morphology. In addition, the fiber membranes not only exhibited a high water contact angle (WCA) (135.56°) and a small maximum pore size (dmax) (1.77 μm), but also demonstrated a large hydrostatic pressure (116.86 kPa) and a moderate water vapor transmission rate (WVTR) (3.53 kg m−2 d−1). The PVDF/SiO2 fibrous membranes with good waterproof and moisture permeability obtained in this work are expected to improve the comfort of protective textiles and expand the application range.

Superhydrophobic/superoleophilic polyurethane /reduced graphene oxide/ sponge for efficient oil-water separation and photothermal remediation

Due to the rapid development of global industrialization, the frequent occurrence of organic matter leakage and oil leakage accidents has led to increasingly serious environmental pollution. Therefore, this paper has proposed a facile and affordable method for creating oil water separation materials, and successful creating a super hydrophobic/super oleophilic functional porous polyurethane sponge modified by reduced graphene oxide and polydopamine (PDA-rGO-PU). Dopamine undergoes a self-polymerization event that creates polydopamine, which is subsequently coated on a polyurethane framework to create a sponge structure with several active sites. The surface of the modified sponge structure was coated with graphene oxide by a simple drop-coating method, and graphene oxide coated on the surface of polydopamine was reduced to create the superhydrophobic/superoleophilic material. The PDA-rGO-PU demonstrated strong anti-adhesion properties and a high oil-water separation efficiency of 99.8 % while having high water contact angles of 155 ° ± 3 ° and oil contact angles (OCA) of 0 °. It has a strong ability to adsorb various oils and organic solvents, the excellent photothermal effect allows PDA-rGO-PU to raise temperature by 37.9 % in the presence of light. PDA-rGO-PU has good continuous oil sorption performance after installing the pump. When under simulated lighting conditions, the sorption time of modified sponge on crude oil was shortened by 2.3 times.

Characterizations of the pullulan/sodium alginate coatings incorporated with sodium silicate and EDTA-2Na and the antifungal effect on citrus green mold

Citrus has suffered great losses from postharvest fungal diseases. The strategy of polysaccharide-based coating combined with antimicrobial salts was introduced to preserve citrus and control green mold. Sodium silicate and ethylene diamine tetraacetic acid-2Na (EDTA-2Na) (SE) were incorporated with pullulan (PUL)/sodium alginate (SA) solutions to fabricate PSA-SE systems. The results indicated that the PSA-SE films had good biocompatibility based on hydrogen bonds and showed uniform and dense. The molecular of PUL and SA were assembled through entanglement to form a network structure and the surface roughness of the PSA-SE films increased with the addition of SA. The P3SA2-SE film indicated appropriate tensile strength and elongation at break, as well as the lowest water vapor permeability. The carbon dioxide and oxygen permeability and dissolution of P3SA2-SE film were at low values. The P3SA2-SE film had the highest water contact angle (66°). With the addition of SA, the absorbance of the PSA-SE films increased, which was conducive to light blocking. The antifungal experiments revealed that the P3SA2-SE coating showed a significant effect on controlling citrus green mold, especially in Citrus sinensis Osbeck ‘Lane Late’ almost completely inhibited Penicillium digitatum (P44). This study will promote the development of citrus postharvest disease control.

One-pot fabrication of hydrophobic, superelastic, harakeke-derived nanocellulose aerogels with excellent shape recovery for oil adsorption and water-in-oil emulsion separation

Cellulose-based aerogels have attracted significant attention for oil/water separation due to their high porosity, large specific surface area and high adsorption capacity. However, their intrinsic hydrophilicity, and inadequate mechanical properties have often limited their practical applications. Traditional freeze-dried cellulose aerogels exhibit unsatisfactory elasticity and require a separate surface modification process to adjust the surface wettability. In this study, we present a novel one-pot fabrication strategy which simultaneously achieves the crosslinking of individual cellulose nanofibers and the hydrophobic modification of the surface wettability. Following directional freeze-drying, hydrophobic, superelastic, and anisotropic cellulose-based aerogel was prepared from the 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-oxidized cellulose nanofibers, isolated from harakeke (New Zealand native flax). The resulting aerogel exhibits a high water contact angle of 142°, good compressive recovery performance (85 % recovery of the original height after 100 compression cycles at 70 % strain), and outstanding adsorption capacity for various types of oil and organic solvents (80–105 g/g). Furthermore, the aerogel could also be used as a filter to separate surfactant stabilized water-in-oil emulsions with a high flux (782 L m−2 h−1) and a high separation efficiency (98.7–99.2 %). The novel aerogel prepared in this study is expected to have great potential for practical applications in oily wastewater remediation.

Advanced eco-friendly dual-layer coating: Combining superhydrophobicity with smart self-healing for superior metal protection

In this study, a double-layer composite coating was developed by integrating a superhydrophobic top layer with a smart self-healing bottom layer. The superhydrophobic top coating demonstrated a high water contact angle of up to 153°, showcasing excellent mechanical properties, corrosion resistance, self-cleaning ability, and resistance to fouling, ice formation, and scaling. Notably, the anti-scaling property of the coating remained above 80 % after 36 h of immersion. The bottom layer, composed of waterborne epoxy resin and pH-responsive smart fillers, provided enhanced corrosion resistance and self-repairing capabilities while maintaining environmental friendliness. Experimental results indicated that the impedance value of the composite coating could reach 1010 Ω·cm2 at 0.01 Hz, significantly surpassing the corrosion resistance of traditional waterborne epoxy resin coatings. Additionally, the protective effect of the superhydrophobic top layer was evident even after the coating was damaged, suggesting a novel approach for employing superhydrophobic coatings in metal corrosion protection.

Preparation and performance control of ultra-low near-infrared reflectivity coatings with super-hydrophobic and outstanding mechanical properties

The development of ultra-low near-infrared reflectivity coatings with outstanding engineering properties remains a challenge in laser stealth materials research. Herein, we reported a laser stealth coating with outstanding mechanical properties, super-hydrophobicity, and an ultra-low near-infrared reflectivity for 1.06 μm wavelength. The effects of the mass ratio of graphene to nano-SiO2, the proportion of total filler, the addition of KH560, the mass ratio of Polydimethylsiloxane (PDMS) to acrylic-modified polyurethane (APU), and the addition of dioctyl phthalate (DOP) on the coating properties were thoroughly discussed. The coating can achieve a low reflectivity of 9.3% at 1.06 μm and a high water contact angle of 152° at a mass ratio of 7:3 for PDMS to APU and 6:4 for graphene to nano-SiO2 with a total filler amount of 40 wt%. KH560 can play a bridging role between the blended resin matrix and nano-SiO2, which can significantly improve the impact strength of the coating. The DOP, which contains a polar ester group and a non-polar carbon chain structure, can be inserted between the molecular chains of the resin to weaken the intermolecular force of the resin, so that the flexibility of the coating can be significantly improved. Adding KH560 at 4 wt% and DOP at 1 wt%, resulted in a coating with ultra-low near-infrared reflectivity of 1.06 μm (9.3%), super-hydrophobic properties, outstanding adhesion strength (grade 2), flexibility (2 mm), and impact strength (50 kg cm). The above super-hydrophobic ultra-low near-infrared reflectivity coating has significant potential for use in the field of laser stealth equipment, and it can serve as a useful reference for optimizing the mechanical properties of super-hydrophobic functional coatings.

Low-density, water-repellent, and thermally insulating cellulose-mycelium foams

This work explored whether partial cellulose bioconversion with fungal mycelium can improve the properties of cellulose fibre-based materials. We demonstrate an efficient approach for producing cellulose-mycelium composites utilizing several cellulosic matrices and show that these materials can match fossil-derived polymeric foams on water contact angle, compression strength, thermal conductivity, and exhibit selective antimicrobial properties. Fossil-based polymeric foams commonly used for these applications are highly carbon positive, persist in soils and water, and are challenging to recycle. Bio-based alternatives to synthetic polymers could reduce GHG emissions, store carbon, and decrease plastic pollution. We explored several fungal species for the biofabrication of three kinds of cellulosic-mycelium composites and characterized the resulting materials for density, microstructure, compression strength, thermal conductivity, water contact angle, and antimicrobial properties. Foamed mycelium-cellulose samples had low densities (0.058 – 0.077 g/cm3), low thermal conductivity (0.03 – 0.06 W/m∙K at + 10 °C), and high water contact angle (118 – 140°). The recovery from compression of all samples was not affected by the mycelium addition and varied between 70 and 85%. In addition, an antiviral property against active MS-2 viruses was observed. These findings show that the biofabrication process using mycelium can provide water repellency and antiviral properties to cellulose foam materials while retaining their low density and good thermal insulation properties.Graphical

The influence of molecular weight on the anticorrosion properties of chitosan coatings

The effort to replace toxic compounds with natural alternatives led to intensive investigations on the use of polysaccharides as coatings for corrosion protection. Biological macromolecules, such as chitosan, demonstrate great potential for the development of sustainable anticorrosion coatings. However, the role played by important properties, such as molecular weight, on the performance of the coatings, remains unclear. In this paper, the influence of molecular weight on the anticorrosion properties of chitosan coatings is investigated using AA2024-T3 aluminum alloy as substrate. Chitosan of three different molecular weights were used for the preparation of coatings and free-standing films, and their properties (morphology, swelling degree, and water contact angle) were evaluated. The corrosion performance of the coated samples was investigated by an atmospheric corrosion essay and by electrochemical impedance spectroscopy, in NaCl 3.5 % solution. The results show that the low-molecular-weight chitosan coatings present the lowest swelling degree (603 %), highest water contact angle (86.4°), lowest porosity, and superior performance in both corrosion tests, reaching impedances close to 105Ωcm2 even after seven days of exposure to corrosive solution.

Treatment of various saline wastewaters by membrane distillation with omniphobic polyvinyl alcohol membrane

An omniphobic membrane was fabricated to address the issues associated with traditional hydrophobic membrane wetting in membrane distillation (MD) and used to treat industrial high-salinity wastewater. An electrospun nanofiber membrane with excellent hydrophobicity (high water contact angle value of 157°) was fabricated by hydrophilic, biodegradable, and inexpensive polyvinyl alcohol (PVA) via electrospinning method modified by glutaraldehyde cross-linking, Al2O3 nanoparticles coating, and impregnated fluorination. Moreover, the resulting membrane presented satisfactory wettability resistance in treating solutions containing 20 % NaCl and sodium dodecylbenzene sulfonate. In comparison to commercial polyvinylidene fluoride membrane, the omniphobic PVA membrane showcased remarkable separation performance when treating coal gasification brine and acid mine drainage. Based on our findings, we conducted a comprehensive evaluation of the anti-wetting and anti-scaling properties of the omniphobic PVA membrane. Furthermore, we delved into an in-depth analysis and discussion of the mechanisms behind the low surface energy and multi-level re-entrant structures that contribute to these properties. The results indicate that the omniphobic PVA membrane holds potential for application in MD processes aimed at water recovery from industrial wastewater containing complex compounds.