A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

Nanotechnology in wood science: Innovations and applications

Application of nanomaterials is gaining tremendous interest in the field of wood science and technology for value addition and enhancing performance of wood and wood-based composites. This review focuses on the use of nanomaterials in improving the properties of wood and wood-based materials and protecting them from weathering, biodegradation, and other deteriorating agents. UV-resistant, self-cleaning (superhydrophobic) surfaces with anti-microbial properties have been developed using the extraordinary features of nanomaterials. Scratch-resistant nano-coatings also improve durability and aesthetic appeal of wood. Moreover, nanomaterials have been used as wood preservatives for increasing the resistance against wood deteriorating agents such as fungi, termites and borers. Wood can be made more resistant to ignition and slower to burn by introducing nano-clays or nanoparticles of metal-oxides. The use of nanocellulose and lignin nanoparticles in wood-based products has attracted huge interest in developing novel materials with improved properties. Nanocellulose and lignin nanoparticles derived/synthesized from woody biomass can enhance the mechanical properties such as strength and stiffness and impart additional functionalities to wood-based products. Cellulose nano-fibres/crystals find application in wide areas of materials science like reinforcement for composites. Incorporation of nanomaterials in resin has been used to enhance specific properties of wood-based composites. This review paper highlights some of the advancements in the use of nanotechnology in wood science, and its potential impact on the industry.

Effect of NaOH Pretreatment on Permeability and Surface Properties of Three Wood Species

To improve the permeability of wood, three chemical reagents were used to pretreat Chinese fir, white oak, and poplar. Through a factorial experiment with the mass change rate of the wood as the indicator, NaOH was preliminarily selected as the pretreatment agent. Further orthogonal experiments were conducted to explore the effects of NaOH concentration, temperature, and treatment time on the mass change rate, dye uptake rate, transverse dye penetration rate, and color difference of the wood. A fuzzy, comprehensive analysis was used to optimize the pretreatment process. The results showed that after NaOH pretreatment, the highest mass change rates of Chinese fir, white oak, and poplar were 11.30, 10.66, and 8.53%, respectively. Compared with untreated wood, the dye uptake rate of three wood species increased by 1.05, 1.43, and 1.13 times, respectively; the radial dye penetration rate increased by 5.05, 4.14, and 3.38 times, respectively; and the tangential dye penetration rate increased by 3.91, 3.45, and 3.84 times, respectively. These findings indicate an enhancement in permeability for all three wood species following NaOH pretreatment. The brightness of the three wood species decreased after NaOH pretreatment, while the yellow and red colors increased in Chinese fir and poplar and decreased in white oak. Scanning electron microscopy showed that pits in the wood opened after pretreatment, while extractives decreased. Infrared spectroscopy analysis indicated varying degrees of extraction effects from NaOH pretreatment across the three wood species, along with increased active hydroxyl groups within the wood structure. X-ray diffraction analysis revealed that NaOH dissolved noncrystalline substances in wood, leading to improved crystallinity. These experimental findings provide essential data for future endeavors in wood pretreatment and subsequent staining processes.

Study on the Difference of Superhydrophobic Characteristics of Different Wood Furniture Substrates

To enhance the stability of wood and decrease restrictions on its use in the furniture industry, hydrophobic modification can be employed to confer waterproof, anti-fouling, and self-cleaning properties. The present study outlines the preparation of silica sol using the sol–gel method, followed by impregnation and chemical vapor deposition methods to modify the sol. After grafting 1H,1H,2H,2H-perfluoro-decyl trichlorosilane (FDTS), hydrophobic and superhydrophobic properties were imparted to the wood substrate. To explore the correlation between the surface properties of the wood substrate and superhydrophobic coatings, the densities, porosities, and surface roughness of various tree species were compared. The results showed that the sol–gel method successfully constructed hydrophobic coatings on different wood substrates, with six samples (poplar, elm, toon wood, paulownia, ashtree, and black walnut) achieving superhydrophobic surfaces, with densities ranging from 0.386 to 0.794 g/cm3, porosity ranging from 13.66 to 42.36%, roughness ranging from 4.660 to 11.244 um, and maximum water contact angle of 165.2°. Whereas beech and rosewood only reach the hydrophobic surface. Although the coatings demonstrated good resistance to water, pollutants, self-cleaning, and chemical agents, further improvements are necessary to enhance mechanical wear resistance.

UV-curable self-matting waterborne polyurethane acrylate coating via self-wrinkled surface during curing in open-air

This study developed and evaluated a series of ultraviolet (UV) curable self-matting waterborne polyurethane acrylate (UV-WPUA) coatings based on the self-wrinkled surface during UV-curing in the open-air. This method is simple, efficient, eco-friendly, and it does not require complicated or expensive equipment. The FT-IR spectrum indicates that the peaks of C[double bond, length as m-dash]C in UV-WPUA have disappeared after UV irradiation. The gloss value of the UV-WPUA cured film can be affected by the wrinkles on the surface of the film and adjusted it by controlling the content of the photoinitiator in the liquid coating, since the content influences the dimensions of the wrinkles. As the height of the wrinkle increased, the gloss value of the UV-WPUA cured film decreased, and when the incident angles are 20° and 60°, the gloss values are less than 3 GU and 5 GU, respectively. Moreover, the cured film has a maximum water contact angle of 109°, which is affected by wrinkles and positively correlated with the surface roughness of the film. Furthermore, the cured film has excellent properties of thermal stability, tensile strength, pencil hardness, cross-cut adhesion and resistance to abrasion properties, making it well suited for the furniture, leather, and textile applications.

New Poplar-Derived Biocomposites via Single-Step Thermoforming Assisted by Phosphoric Acid Pretreatment

One-step thermoforming represents an effective approach to preparing glue-free biocomposites. This study aimed to produce glue-free biocomposites with high-temperature resistance and mechanical properties using phosphoric acid pretreatments combined with thermoforming. Due to the hot-moulding process, the cell wall was destroyed, which allowed the fibres to adhere closely together. Most hemicelluloses were hydrolysed through pretreatment with phosphoric acid, and the contact area between the cellulose and lignin was significantly increased. The biocomposites prepared by ball milling demonstrated remarkable flexural strength (49.03 MPa) and tensile strength (148.23 MPa). Moreover, they had excellent thermal stability, with the maximum temperature for pyrolysis rate at 374 °C, which was much higher than that of poplar (337 °C). In addition, the material released no formaldehyde during the preparation process, which is in line with the concept of green production.

Micro-replication platform for studying the structural effect of seed surfaces on wetting properties

Biological surfaces in plants are critical for controlling essential functions such as wettability, adhesion, and light management, which are linked to their adaptation, survival, and reproduction. Biomimetically patterned surfaces replicating the microstructures of plant surfaces have become an emerging tool for understanding plant–environment interactions. In this study, we developed a two-step micro-replication platform to mimic the microstructure of seed surfaces and demonstrated that this initial platform can be used to study seed surface–environment interactions. The two-step process involved the extraction of a simplified seed surface model from real seeds and micro-replication of the simplified seed surface model using nanoimprint lithography. Using Allium seeds collected from Mongolia and Central Asia as the model system, we studied the wettability of biological and synthetic seed surfaces. We could independently control the material properties of a synthetic seed surface while maintaining the microstructures and, thereby, provide clear evidence that Allium seed surfaces were highly wettable owing to the high surface energy in the epidermal material rather than a microstructural effect. We expect that this platform can facilitate study of the independent effect of microstructure on the interaction of seed surfaces with their surroundings and contribute to research on the evolution of plant–environment interactions.

Enhancement of Bacterial Anti−Adhesion Properties on Robust PDMS Micro−Structure Using a Simple Flame Treatment Method

Biofilm-associated infections caused by an accumulation of micro-organisms and pathogens significantly impact the environment, health risks, and the global economy. Currently, a non-biocide-releasing superhydrophobic surface is a potential solution for antibacterial purposes. This research demonstrated a well-designed robust polydimethylsiloxane (PDMS) micro-structure and a flame treatment process with improved hydrophobicity and bacterial anti-adhesion properties. After the flame treatment at 700 ± 20 °C for 15 s, unique flower-petal re-entrant nano-structures were formed on pillars (PIL-F, width: 1.87 ± 0.30 μm, height: 7.76 ± 0.13 μm, aspect ratio (A.R.): 4.14) and circular rings with eight stripe supporters (C-RESS-F, width: 0.50 ± 0.04 μm, height: 3.55 ± 0.11 μm, A.R.: 7.10) PDMS micro-patterns. The water contact angle (WCA) and ethylene glycol contact angle (EGCA) of flame-treated flat-PDMS (FLT-F), PIL–F, and C–RESS-F patterns were (133.9 ± 3.8°, 128.6 ± 5.3°), (156.1 ± 1.5°, 151.5 ± 2.1°), and (146.3 ± 3.5°, 150.7 ± 1.8°), respectively. The Escherichia coli adhesion on the C-RESS-F micro-pattern with hydrophobicity and superoleophobicity was 42.6%, 31.8%, and 2.9% less than FLT-F, PIL-F, and Teflon surfaces. Therefore, the flame-treated C-RESS-F pattern is one of the promising bacterial anti-adhesion micro-structures in practical utilization for various applications.

Nanocellulose Based Filtration Membrane in Industrial Waste Water Treatment: A Review

In the field of industrial wastewater treatment, membrane separation technology, as an emerging separation technology, compared with traditional separation technology such as precipitation, adsorption, and ion exchange, has advantages in separation efficiency, low energy consumption, low cost, simple operation, and no secondary pollution. The application has been expanding in recent years, but membrane fouling and other problems have seriously restricted the development of membrane technology. Natural cellulose is one of the most abundant resources in nature. In addition, nanocellulose has characteristics of high strength and specific surface area, surface activity groups, as well as being pollution-free and renewable, giving it a very wide development prospect in many fields, including membrane separation technology. This paper reviews the current status of nanocellulose filtration membrane, combs the widespread types of nanocellulose and its derivatives, and summarizes the current application of cellulose in membrane separation. In addition, for the purpose of nanocellulose filtration membrane in wastewater treatment, nanocellulose membranes are divided into two categories according to the role in filtration membrane: the application of nanocellulose as membrane matrix material and as a modified additive in composite membrane in wastewater treatment. Finally, the advantages and disadvantages of inorganic ceramic filtrations and nanocellulose filtrations are compared, and the application trend of nanocellulose in the filtration membrane direction is summarized and discussed.