The 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 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 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 abstractCellulose-based triboelectric nanogenerators (TENGs) can provide power for various monitoring devices and are environmentally friendly and sustainable. Chemical functional modification is a common method to improve the electrical output performance of cellulose-based TENGs. In this work, an environmentally friendly high-performance triboelectric nanogenerator based on a polydopamine/cellulose nanofibril (PDA/CNF) composite membrane and fluorinated ethylene propylene was developed. Dopamine generates polydopamine nanoparticles through oxidative self-polymerization and adheres to the surface of nanofibers. The synergistic effect of amino group introduction and membrane surface microstructure effectively enhanced the output performance of TENGs to a certain extent. The effects of PDA content, CNF composite film thickness and different working conditions on the electrical output were systematically investigated. The optimized PDA/CNF-TENGs exhibited an enhanced electrical output performance with voltage, current, and power density values of ≈205 V, ≈20 µA, and ≈48.75 μW·cm?2, respectively. The PDA/CNF-TENGs exhibited stable and identifiable signals when used as a self-powered sensor for human motion monitoring, showing the potential prospects of cellulose materials for TENGS and other electronic applications.
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 abstractThe development of a versatile platform that can separate oil/water mixture, remove dye from water, and purify wastewater is extremely desirable, yet still hard to realize. Herein, to address this challenge, a composite hydrogel was produced by freezing–thawing treatment using chitosan, polyvinyl alcohol, and carbon black as the raw materials. The obtained hydrogel displayed both slippery oil-repellency and water-affinity in air, underwater, when submerged in oil, and exploiting this special wettability, the hydrogel coated mesh can be used to separate oil/water mixtures efficiently. After 25 oil–water separation cycles, the hydrogel-coated filter still had a separation efficiency of over 98%. With its superhydrophilicity and active functional groups, the resulting hydrogel was able to absorb dye molecules dissolved in water effectively. Due to the photothermal effect of carbon black, the local temperature of the hydrogel was increasing quickly under sunlight illustration, which allowed it to be an advanced platform for daily wastewater purification through solar distillation.
Graphical abstractA versatile hydrogel platform for oil–water separation, dye adsorption, and domestic wastewater purification was developed.
Wearable flexible sensors with quick response time and high stability are required in the fields of human motion detection, personal health monitoring, and artificial electronic skin. However, their design remains a challenge. To address this need, we fabricate a piezoresistive sensor with a wide detection limit, fast response time, and excellent stability in this work. Nickel (Ni) and copper (Cu) films are deposited on cotton fabric (CF) by in-situ polymerization of polyaniline (PANI) using magnetic filtration cathode vacuum arc deposition technology to obtain copper/polyaniline cotton (Cu/PANI/CF) and nickel/polyaniline cotton (Ni/PANI/CF). The pressure sensor is then fabricated by self-assembly. The proposed pressure sensor has a wide detection limit (0–180 kPa), rapid response time (30 ms), high cycle stability (>5000), and can detect the movement of each joint of the human body (such as the knee, finger, elbow, etc.). The sensor can also monitor different facial micro-expressions, including smiles and blinking. Based on the practical application of human motion signals and the detection of subtle stress, the proposed sensor demonstrates significant potential as a wearable electronic product for health monitoring.
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 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 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 abstractThis study introduces an effective route to fabricate chitosan (CS)-based film. The films were prepared through cross-linking reaction between CS and hydroxyethyl cellulose (HEC) using epichlorohydrin (ECH) as the cross-linker and simultaneously in-situ loading with CuO nanoparticles. FT-IR and loading efficiency results indicated the occurrence of inter- and intra-molecular cross-linking reaction between CS and HEC. XRD and EDS analyses showed that the CuO nanoparticles were evenly deposited onto CS film matrixes. SEM characterization showed that the films were of compact, dense and uniform cross morphologies, as well as obvious voids. The films also exhibited desired swelling ratio and water vapor permeability. The enhanced tensile strength was obtained with a maximum value of 77.02?±?3.26 MPa, while the stretch-ability slightly decreased. The thermal stability of the films decreased after cross-linking with HEC. The antibacterial ability of the films was generally improved with the increase of HEC and ECH contents.
Graphical abstractPreparation and properties of epichlorohydrin-cross-linked chitosan/hydroxyethyl cellulose based CuO nanocomposite films
Exploitation 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 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 abstractIn this paper, we developed a microbial route to fabricate wood-inspired biomimetic composites comparable to natural wood. Focusing on the chemical composition of woody biomass, we performed in situ bioprocessing of bacterial cellulose (BC) imbibed in modified cationic lignin (Catlig), which exhibited significant bioactivity in improving the microbial growth dynamics. The structural and morphological characteristics were enhanced by the formation of hydrophobic and electrostatic interactions between BC and Catlig during biosynthesis. Microbially derived BC/Catlig composites exhibited enhanced thermal stability and crystallinity, with oriented cellulose fibers. The tensile properties, toughness, and specific strength of BC/Catlig composites were comparable to those of a heavy wood species (Zelkova serrata) under hydrated conditions and synthetic soft materials.
Graphic abstractA variety of liquid energy exists in papermaking engineering and has not yet been developed and utilized. In addition, for the papermaking industry, the presence of slime can seriously affect the quality of the finished paper and can lead to paper breaking. The current slime control strategies cannot completely solve the problem and also have some low toxicity. In this study, a method of self-powered sterilization of cellulose fibers by using triboelectric pulsed direct current is reported. A liquid–solid triboelectric nanogenerator (L–S TENG) was used to convert the liquid energy of nanocellulose suspension into electrical energy and convert this electrical energy into pulsed direct current for self-powered sterilization of cellulose fiber. A hydrophobic coating material is used as solid triboelectric material and electrode for sterilization. Driven by L–S TENG, the electrodes exhibited an excellent sterilization rate against four microorganisms including Escherichia coli, Aspergillus niger, Candida albicans, and Klebsiella pneumoniae, which from slime in the papermaking industry. This study could provide a basic research theory for liquid energy harvesting in the papermaking industry, and also provide a new strategy for pulp sterilization.
Graphical abstractCarbon quantum dots (CQDs) co-doped with N, P and S derived from expired milk was prepared by a simple hydrothermal method. By dipping pure cotton face towel (PCFT) into CQDs ink, a flexible all-biomass CQDs/PCFT sensor was prepared for the first time. Due to the heteroatom doping, extremely small particle size of CQDs and excellent permeability of CQDs/PCFT film, the flexible CQDs/PCFT sensor showed the high sensitivity and bending stability. In the range of 0–60° bending states, the responses of CQDs/PCFT sensor to four target analytes changed by less 5.0%. After 3000 bending of 60°, the maximum change of the response to the target analytes was only 6.4%. Interestingly, due to the abundant functional groups and defects of CQDs, the flexible CQDs/PCFT sensor displayed sensing curves of different shapes for different target analytes. In this way, by establishing a database of sensing curves of target analytes, multiple analytes can be detected discriminatively by relying only on single sensor with the help of image recognition. This work provided a reference for the development of cotton fiber based all biomass flexible gas sensor.
Graphical abstractThe complex anatomy of teeth limits the accessibility and efficacy of regenerative treatments. Therefore, the application of well-known inducers as injectable hydrogels for the regeneration of the dentin-pulp complex is considered a promising approach. In this regard, this study aimed to develop an injectable hydrogel containing mineral trioxide aggregate (MTA). The injectable chitosan/oxidized-nanocrystalline cellulose/MTA (CS/OCNC/MTA) hydrogels were prepared, and the physicochemical properties of these hydrogels were evaluated by TGA, FTIR, Rheological analysis, and SEM. Moreover, the effect of MTA on the swelling and degradability of scaffolds was assessed. The proliferative effects of synthesized hydrogels were also determined on human dental pulp stem cells (hDPSCs) by MTT assay. For induction of differentiation and biomineralization in these cells, the alkaline phosphatase activity and Alizarin Red S staining tests were performed in the presence of fabricated scaffolds. The proliferation of hDPSCs was significantly increased in the presence of these hydrogels. Moreover, the addition of MTA to hydrogel structure dramatically improved the differentiation of hDPSCs. These results suggested that this novel injectable hydrogel provides appropriate physiochemical properties and can be considered a promising scaffold for regenerative endodontic procedures.
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 abstractThe 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 abstract