The development of a simple surface barrier discharge plasma device is presented to enable more widespread access to and utilization of plasma technology. The application of the plasma device was demonstrated for pretreatment of wood prior to application of protective coatings for outdoor usage. The coatings' overall performance was increased, showing a reduction or absence of cracking due to weathering on plasma-pretreated specimens. Moreover, after ten months of outdoor weathering, the plasma-pretreated specimens showed fewer infections with biotic factors and improved adhesion performance in cross-cut tests, while the surface gloss performed independently from plasma pretreatment. In contrast to that, plasma-pretreated specimens were slightly more prone to discoloration due to outdoor weathering, whereas the plasma pretreatment did not impact the initial color after coating application.
Graphic abstractOceans and soils have been contaminated with traditional plastic due to its lack of degradability. Therefore, green biopolymer composites reinforced with cellulose nanocrystal-zinc oxide hybrids (ZnO hybrids) with good biodegradation ability provided a positive impact on reducing environmental challenges. In this work, the effect of various morphologies of ZnO hybrids on the biodegradation ability of poly(butylene adipate-co-terephthalate), PBAT) under seawater, soil burial, and UV aging conditions were investigated. Sheet-like ZnO hybrids (s-ZnO hybrid) efficiently enhanced the mechanical, UV-blocking properties and biodegradation ability of PBAT nanocomposite films. Compared to neat PBAT, the best tensile strength of PBAT nanocomposite with 2 wt% s-ZnO hybrid was increased by 15.1%, meanwhile this nanocomposite films showed the highest biodegradation rate after 80 days of soil degradation and 90 days of seawater degradation. Besides, three possible biodegradation mechanisms of green PBAT nanocomposite films were presented, hinting that such PBAT nanocomposite have great promising packaging applications.
Graphic abstractLife-threatening diseases, especially those caused by pathogens and harmful ultraviolet radiation (UV-R), have triggered increasing demands for comfortable, antimicrobial, and UV-R protective clothing with a long service life. However, developing such textiles with exceptional wash durability is still challenging. Herein, we demonstrate how to fabricate wash durable multifunctional cotton textiles by growing in situ ZnO-TiO2 hybrid nanocrystals (NCs) on the surface of cellulosic fabrics. The ZnO-TiO2 hybrid NCs presented high functional efficiency, owing to their high charge transfer/separation. Ultrafine fiber surface pores, utilized as nucleating sites, endowed the uniform growth of NCs and their physical locking. The resulting fabrics presented excellent UV protection factors up to 54, displayed bactericidal efficiency of 100% against Staphylococcus aureus and Escherichia coli, and optimum self-cleaning efficacy. Moreover, the functionalized textiles exhibited robust washing durability, maintaining antibacterial and anti-UV-R efficiency even after 30 extensive washing cycles.
Graphical abstractBacterial cellulose (BC) is a polymer with interesting conformation and properties. BC can be obtained in different shapes and is easily modified by chemical and physical means, so its applications in the production of new materials and nanocomposites for different purposes have been in the focus of many research projects. However, one of the major challenges to address in bacterium-derived polymer technology is to find suitable carbon sources as substrates that are cheap and do not compete with food production for achieving large scale industrial applications. Agricultural wastes are defined as the residues from the growing and processing of raw agricultural products such as crops, fruits, vegetables and dairy products. Their composition can vary depending on the type of agricultural activity and harvesting conditions, but these residues are suitable for the production of BC. The aim of this review is to give insight into the production of BC using agro-wastes and an overview of the most interesting and novel applications of this biopolymer in different areas i.e. environmental applications, optoelectronic and conductive devices, food ingredients and packaging, biomedicine, and 3D printing technology.
Graphic abstractIncreasing electromagnetic pollution calls for electromagnetic interference (EMI) shielding materials, especially sustainable, lightweight, and environmentally stable, biomass-based materials. MXene-coated wood (M/wood) is prepared by simply spraying MXene sheets on the wood surface. Varying this spray coating manipulates the shielding performance and its application to different wood species. The M/wood exhibits high electrical conductivity (sheet resistance is only 0.65 Ω/sq) with an excellent EMI shielding effectiveness of 31.1 dB at 8.2?~?12.4 GHz and is also fire retardant. Furthermore, waterborne acrylic resin (WA) is coated on M/wood to enhance environmental stability. The WA coating improves EMI shielding performance stability after water-soaking and drying testing and prevents the peeling of MXene from wood. These satisfactory properties of WA-M/wood and the facile manufacturing approach promote the feasibility of wood-based EMI shielding materials.
Graphical abstractCellulose nanocrystals (CNCs) with high crystallinity exhibit high mechanical stiffness and strength. However, the high dispersibility of CNCs results in limited spinnability and orientation. In this study, oxidized nanocellulose was selected to obtain regionally oxidized CNCs (RO-CNC) with carboxyl groups appended. For the formation of orientable and extensible RO-CNC filaments, chitosan was introduced as the sheath solution to induce orientation by electrostatic action. The chemical structures were analyzed by Fourier transform infrared spectroscopy. The morphology of the oriented CNCs filaments was characterized by scanning electron microscopy and wide-angle X-ray scattering. Analysis of the relationship between the mechanical strength and the CNCs directional arrangement revealed that the mechanical strength of the composite fibers increased with the injection speed ratio as a result of the orientation of the RO-CNC. The mechanical strength of the oriented reinforced composite filaments reached as high as 104 MPa with an orientation index of 0.73. The tensile strength and elastic modulus of the filaments increased by 33% and 20%, respectively, compared to the unmodified CNCs spun fiber.
Graphic abstractThe surgical masks have been essential consumables for public in the COVID-19 pandemic. However, long-time wearing masks will make wearers feel uncomfortable and massive discarded non-biodegradable masks lead to a heavy burden on our environment. In this paper, we adopt degradable chitosan@silver (CS@Ag) core–shell fibers and plant fibers to prepare an eco-friendly mask with excellent thermal comfort, self-sterilization, and antiviral effects. The thermal network of CS@Ag core–shell fibers highly improves the in-plane thermal conductivity of masks, which is 4.45 times higher than that of commercial masks. Because of the electrical conductivity of Ag, the fabricated mask can be electrically heated to warm the wearer in a cold environment and disinfect COVID-19 facilely at room temperature. Meanwhile, the in-situ reduced silver nanoparticles (AgNPs) endow the mask with superior antibacterial properties. Therefore, this mask shows a great potential to address the urgent need for a thermally comfortable, antibacterial, antiviral, and eco-friendly mask.
Graphical abstractMembrane applications for the separation of surfactant-stabilized emulsions are often constrained by a deficiency in permeability and anti-fouling properties. Herein, special wetted cotton fabric with a protective layer (P-MH@CF) for durable anti-fouling performance was synthesized by a two-step method, which was related to interfacial ion migration technology and unilateral spraying treatment. Permeability of water and separation performance of P-MH@CF membrane were investigated systematically. Emulsions stabilized by anionic, cationic, or non-ionic surfactant were successfully separated with high efficiency. In the process of separation, the oil droplets surrounded by surfactants were difficult to demulsify and gathered physically on the membrane surface to form a “cream layer”. The stearic acid acted as a protective layer, like a quilt, protecting the membrane from contamination. The membrane retained robust reusability for separation even after the “cream layer” had been washed off, which was promising for the remediation of oily wastewater containing surfactants.
Graphical abstractVulcanized fibers are all-cellulose materials made from cotton and/or wood cellulose after aqueous zinc chloride treatment. These materials were invented in the UK in the mid-nineteenth century and is widely used because of their excellent characteristics, such as impact resistance and electrical insulation. Recently the matured vulcanized fibers have been recognized as renewable and biodegradable materials and reevaluated with advanced cellulose technologies derived from cellulose nanofibers (CNFs) and all-cellulose composites. The microscopic analysis based on the improved freeze-drying method revealed that the strength of vulcanized fiber sheets can be attributed to the chemically defibrillated CNFs. The architecture is similar to all-cellulose composites made from the same raw materials in which the residual cellulose fibers serve as reinforcement, and the CNFs serve as adhesives or matrix components. In this report, we describe the history and structural characteristics of vulcanized fibers and introduce a new aspect in aqueous zinc chloride treatment of cellulose.
Graphical abstractThere are growing research interests in flax fibers due to their renewable ‘green’ origin and high strength. However, these natural fibers easily absorb moisture and have poor adhesion with polymer matrix leading to low interfacial strength for the composites. A hybrid chemical treatment technique combining alkali (sodium hydroxide) and silane treatments is adopted in the current study to modify flax fibers for improved performances of flax/polypropylene composites. Changes in chemical composition, microstructure, wettability, surface morphology, crystallinity and tensile properties of single flax fiber before and after chemical treatments were comprehensively characterized using techniques including SEM, FTIR, AFM, XRD, micro-fiber tester, etc. It was found that hemicellulose and lignin at the fiber surface were removed due to alkali treatment, which helped to reduce moisture absorption of the composites. Alkali-treated flax fibers were later subjected to silane treatment, which helped to improve the compatibility between flax fiber and polypropylene matrix. After alkali-silane hybrid chemical treatment, moisture absorption of the composites was further decreased. At the same time, the interfacial bonding strength between flax and polypropylene is significantly enhanced. All these results validate the great advantage of the hybrid chemical treatment approach for flax/polypropylene composites, which has the potential to promote the application of chemical treatment techniques in the plant fiber composite industry.
Graphic abstractThe horse chestnut seed shell (HC) and chestnut seed shell (CT) were evaluated as renewable, sustainable, and cheap raw materials transformed into valuable products, “cellulose nanocrystals (CNCs).” Alkali and bleaching treatments were performed to obtain horse chestnut cellulose (HCS) and chestnut cellulose (CTS) and subsequently isolated to the horse chestnut cellulose nanocrystal (HC-CNC) and chestnut cellulose nanocrystal (CT-CNC) by sulphuric acid hydrolysis. Raw materials and their products were comparatively investigated at each stage of the isolation process. The cellulose, hemicellulose, and lignin content of HC and CT were determined via chemical composition analysis. The structural analysis was performed using Fourier transform infrared spectroscopy and X-ray diffraction technics for CNCs. Morphological analysis and size range determination of the samples were carried out via atomic force microscopy (AFM) and particle size analysis. Zeta potential and particle size distribution were determined by analyzing the surface and particle size. The thermal behaviors were investigated at different phases of treatments using thermal gravimetric analysis (TGA/DTG). HC-CNC demonstrates a higher crystallinity index value of 85.49% and a lower yield of 20.46%, whereas CT-CNC shows a lower crystallinity of 65.06% and a higher yield of 36.59%. A differentiation in structural, thermal, and morphological properties of extracted celluloses and isolated CNCs was observed depending on the source of the raw materials. However, a morphological alteration in CNC structures has emerged relative to precursor cellulose after the acid hydrolysis process as an essential finding via AFM studies. The solid wastes horse chestnut and chestnut seed shells offer great potential as suitable, sustainable, and environmentally friendly starting raw materials to produce CNC and in applications, including wastewater treatments, biosensing, wound dressing, and reinforcement for polymer composites due to their excellent thermal and structural properties.
Graphical abstractActivated carbon paper-based materials were prepared from softwood pulp, activated carbon powder, and polyester fiber through wet forming process. Then polyethyleneimine was loaded on the activated carbon paper-based materials using physical impregnation method to fabricate green, low cost, and degradable PEI/activated carbon composite paper-based adsorbent materials (PPCA) for the removal of Cr(VI) from drinking water. The surface characteristics of the adsorbent were analyzed by SEM, EDX, BET, FT-IR, and XPS. It was found that the maximum adsorption capacity of Cr(VI) could reach up to 1.58 mg g?1 when the PEI immersion concentration is 1%, the contact time is 180 min, the temperature is 30 °C and pH?=?2. The adsorption of Cr(VI) on PPCA conformed to both the freundlich isotherm model and the quasi-second-order kinetic model, indicating that the adsorption was multi-molecular layer adsorption controlled by chemical reaction process. The adsorption mechanism of Cr(VI) on PPCA included electrostatic attraction, redox and chelation. Overall, this study provides a green, large-scalable production way for the preparation of biodegradable adsorption materials for the efficient removal of Cr(VI) from drinking water aiding the safe management of aqueous system.
Graphical abstractCellulose nanofibril (CNF) aerogels have attracted great interests in recent years due to the low cost, sustainability and biocompatibility of raw CNF. However, the poor thermal stability and flammable feature of CNF aerogels have limited their wider applications. In this paper, polydopamine/CNF composite aerogels with good comprehensive properties are fabricated by modification of CNF with polydopamine and metal coordination bonds crosslinking. The microstructure and properties of composite aerogels are thoroughly characterized by a variety of tests. It is found that the microstructure of aerogels are more regular and the compressive strength of aerogels are enhanced by the incorporation of polydopamine and Fe3+ crosslinking. Importantly, the thermal stability and flame resistance of aerogels are significantly improved, which permit the application of composite aerogels in high-temperature thermal insulation. In addition, the reversible characteristic of metal coordination bonds allows the water induced healing of fractured composite aerogels. This study is expected to provide information for future development of green and high-performance aerogels.
Graphic abstractIn this, an efficient flame retardant composite has been prepared using biowaste derived phosphorous groups decorated graphene supported nanomaterial. The eggshell was utilized as a source of calcium carbonate, which was converted to monocalcium phosphate (CP) by phosphoric acid treatment. As-prepared monocalcium phosphate was functionalized with graphene to prepare graphene functionalized monocalcium phosphate (GCP). The GCP-coated fabric didn't ignite during the flame test and sustained more than 600 s on continuous exposure to flame without changing its initial length and shape. Whereas, graphene oxide (GO), and CP coated cotton fabric burnt out very easily within a short time. The efficient flame retardant property of as synthesized GCP coated cotton fabric was confirmed with a high limiting oxygen index (34.1) and char length of 2.5 cm was generated from the VFT test. The synthesized GCP coated cotton fabric also confirmed efficient flame retardant properties. This facile method enables an easy process for mass production of cost-effective, bio-waste derived nanomaterial for a significantly highly efficient candidate for different applications in sustainable chemistry, including flame-retardant applications.
Graphical abstractUniformly-sized porous cellulose beads functionalized with amidoxime groups were prepared for the first time using a microfluidic method with N-methylmorpholine N-oxide (NMMO) monohydrate as a cellulose solvent. The molten state cellulose dope in NMMO monohydrate (cell/NMMO dope) as a disperse phase and hot mineral oil as a continuous phase were used in a T-junction microfluidic chip to produce uniformly-sized cell/NMMO droplets. Coagulation of the molten state cell/NMMO droplet at high temperature and amidoxime functionalization could prepare the highly-porous spherical amidoxime-functionalized cellulose beads with a uniform fibrous open internal structure. The prepared amidoxime-functionalized cellulose beads showed excellent metal adsorption properties with a maximum adsorption capacity of?~?80 mg g?1 in the case of Cu2+/phthalate ions. The newly developed highly-porous cellulose beads can open many new applications with other proper functionalization at the reactive hydroxyl groups of the cellulose.
Graphic abstractIonic cellulose nanocrystals (CNCs) are interesting surface-active particles for encapsulating a lipophilic liquid in water. A CNC is modified chemically to a negative charge (an S-CNC) by surface treatment with sulfuric acid. Despite the amphiphilic nature of S-CNCs, it is difficult to determine the degree of substitution for emulsification of lipophilic liquids, especially when the surface energy is low and polarity is high. Here, we control the substitution of S-CNCs by desulfation of S-CNCs (dS-CNCs) using a low-concentration hydrochloric acid solution. Decreased surface charge of S-CNCs was expected, and the lipophilic affinity of dS-CNCs increased compared with those of S-CNCs. Six oils with differing surface tensions were selected for determination of the effect of charged CNCs on emulsification. The stability of the emulsion was evaluated by emulsion fraction, emulsion particle size, and surface tension of emulsified solutions from dS-CNCs and oils.
Graphical abstractThis study prepared a waterproof cellulose nanofibril (CNF) sheet via the deposition of an alkyl ketene dimer (AKD) on the sheet’s controlled porous structure. The porosity of the CNF sheet was controlled by drying under different conditions, which included hot-press drying (HD) and solvent-exchange drying (SD), and the effect on the hydrophobization and water-related barrier performance of the sheet were investigated. When the SD sheet was immersed in an AKD wax solution, the sheet exhibited super-hydrophobicity and a lower water vapor transmission rate, compared with the HD sheet. This indicated that the porous structure of the SD sheet enabled AKD to be adsorbed on both the surface and the inner surface and it filled in the pores of the sheet, thereby giving rise to excellent waterproofing properties. The performance of a hydrophobized SD sheet as a water barrier material was comparable to a linear low-density polyethylene film. This study confirms the possibility for AKD wax to be immersed in a porous CNF sheet and used as a potential barrier material in hydrogel packaging.
Graphical abstractExploitation of cotton fabric as electromagnetic interference (EMI) shielding substrates have attracted a growing interest due to their desirable low carbon footprint, economic feasibility, and sustainability. Herein, a facile strategy was proposed for preparing a cellulose-based multifunctional PNIPAAm/PPy hydrogel/cotton (PPHC) EMI shielding composites with simultaneous high-efficient electro-photo-thermal conversion and comfort regulation functions. The PPHC was fabricated via in situ polymerization conductive PPy hydrogel on cotton substrate followed by deposition of PNIPAAm. Benefiting from the unique interconnected three-dimensional networked conductive structure of PPy hydrogel, the obtained PPHC composites exhibited high conductivity (15 mS/cm), and EMI shielding effectiveness (EMI SE?~?40 dB) in the frequency of 8.2–12.3 GHz. Moreover, the PNIPAAm coating endowed the composite fabrics with adjustable wettability performance in response to external temperature, leading to excellent comfort regulation performance. This work provided feasible avenue toward low cost and sustainability cotton-based EMI shielding composites with efficient EMI shielding and comfort regulation performance.
Graphical abstractMultifunctional materials for water purification have attracted significant attention due to the increased water pollution problems. However, fabricating the low-cost, effective, and recyclable separation material for wastewater containing various hazardous substances is still a challenge. Herein, we developed an Ag/TiO2@PDMS coated cotton fabric with self-cleaning ability, high flux, superior visible-light photocatalytic ability, and recyclability via the “powder?+?glue” strategy. The composites are superhydrophobic (water contact angle 157°) and show high separation efficiency. After 20 times of repeated use, the separation efficiency remains 16,322 Lm?2 h?1, and methylene blue (MB) 's degradation rate remains almost unchanged. The high oil purification, catalytic property, excellent stability in harsh conditions, and recyclability enable the material as a satisfactory candidate for water purification.
Graphical abstractA cellulosic material has been synthesized that could efficiently and selectively adsorb organic and inorganic contaminants from aqueous solutions without interference from competing adsorption sites. Cellulose-graft-tetraethylenepentamine molecular imprinted polymer (C-TEPA-MIP) was synthesized by using 4-nitrophenol (4-NP) as the template. The C-TEPA-MIP adsorbent could adsorb 4-NP and Cr(VI) simultaneously and selectively, without being affected by the competitive adsorption sites of each of these pollutants. The adsorption of 4-NP was predominantly due to the imprinted sites of 4-NP in C-TEPA-MIP that were located inside of the adsorbent, whereas that of Cr(VI) was primarily due to the amine groups of TEPA found on the surface of the adsorbent. Compared with the non-imprint polymer synthesized without the template, C-TEPA-MIP showed higher selectivity for both 4-NP and Cr(VI) in unitary and binary systems. In addition, C-TEPA-MIP exhibited good stability and recyclability for 4-NP, which makes it a promising candidate material for applications concerning wastewater treatment.
Graphical abstract