A Versatile 2D Cellulose Platform Strategy from Natural Wood Scaffold.

A wood cell wall with cellulose as the key scaffold is a natural hierarchical lamellar structure. This wood-derived cellulose scaffold has recently attracted enormous attention and interest, but almost all efforts have been devoted to its whole tissue functionalization. Here, we report the short ultrasonic processing of a wood cellulose scaffold to directly generate 2D cellulose materials. The obtained 2D cellulose nanosheets consist of many highly oriented fibrils densely arranged and can be further converted to ultrathin 2D carbon nanosheets. The nanoparticles, nickel-iron layer double hydroxide nanoflowers, manganese dioxide nanorods, and zinc oxide nanostars, are successfully loaded in the 2D nanosheet, providing a versatile 2D platform strategy for excellent 2D hybrid nanomaterials.

Dual-Network Structured Nanofibrous Membranes with Superelevated Interception Probability for Extrafine Particles.

Airborne particulate matter (PM) pollution has caused a public health threat, including nanoscale particles, especially with emerging infectious diseases and indoor and vehicular environmental pollution. However, most existing indoor air filtration units are expensive, energy-intensive, and bulky, and there is an unavoidable trade-off between low-efficiency PM0.3/pathogen interception, PM removal, and air resistance. Herein, we designed and synthesized a two-dimensional continuous cellulose-sheath/net with a unique dual-network corrugated architecture to manufacture high-efficiency air filters and even N95 particulate face mask. Combined with its sheath/net structured pores (size 100-200 nm) consisting of a cellulose framework (1-100 nm diameter), the cellulose sheath/net filter offers high-efficiency air filtration (>99.5338%, Extrafine particles; >99.9999%, PM2.5), low-pressure drops, and a robustness quality factor of >0.14 Pa-1, utilizing their ultralight weight of 30 mg/m2 and physical adhesion and sieving behaviors. Simultaneously, masks prepared with cellulose-sheath/net filters are more likely to capture and block smaller particles than the N95 standard. The synthesis of such materials with their nanoscale features and designed macrostructures may suggest new design criteria for a novel generation of high-efficiency air filter media for different applications such as personal protection products and industrial dust removal.

Bioinspired Construction of Micronano Lignocellulose into an Impact Resistance "Wooden Armor" With Bouligand Structure.

The demand for advanced safeguards has increased with a rise in terrorism and international conflicts. Traditional impact-resistant glass and ceramics have relatively high performance but have several drawbacks as well, such as inflexibility, heaviness, and high processing energy consumption. Herein, we propose sustainable lignocellulosic duplicates: the Pirarucu scale-inspired structures that can serve as "wood armor" with impressive damage tolerance. By accurately assembling a rigid laminated lignocellulose, with a soft shear-thickened fluid interlayer, into a Bouligand-like structure, the artificial wooden armor exhibits a 10-fold increase in impact resistance. This observation is similar to that of typical engineering materials (e.g., ceramics, glass, and alloys). However, our proposed material structure has the capability of blocking the enormous impact of a bullet while notably having approximately half the density of typical engineering materials. The high durability and damage resistance of wooden armor effectively prevents catastrophic damage when it is impacted upon. The design strategy presents a method for lightweight, high-performance, and sustainable bioinspired materials for special security applications.

Cellulose-Based Hybrid Structural Material for Radiative Cooling.

Structural materials with excellent mechanical properties are vitally important for architectural application. However, the traditional structural materials with complex manufacturing processes cannot effectively regulate heat flow, causing a large impact on global energy consumption. Here, we processed a high-performance and inexpensive cooling structural material by bottom-up assembling delignified biomass cellulose fiber and inorganic microspheres into a 3D network bulk followed by a hot-pressing process; we constructed a cooling lignocellulosic bulk that exhibits strong mechanical strength more than eight times that of the pure wood fiber bulk and greater specific strength than the majority of structural materials. The cellulose acts as a photonic solar reflector and thermal emitter, enabling a material that can accomplish 24-h continuous cooling with an average dT of 6 and 8 °C during day and night, respectively. Combined with excellent fire-retardant and outdoor antibacterial performance, it will pave the way for the design of high-performance cooling structural materials.

Artificial Wooden Nacre: A High Specific Strength Engineering Material.

Nacre, an organic-inorganic composite biomaterial that forms an ordered multilayer microstructure after years of slow biomineralization, is known as the strongest and toughest material within the mollusc family. Its unique structure provides inspiration for robust artificial engineering materials. Lignocellulose is ultralightweight, abundant, and possesses a high mechanical performance and has been used for ages as a significant renewable raw material in wooden engineering composites. However, the inherent lack of mechanical properties of current wooden composites associated with the fragile microstructure has limited their applications in advanced engineering materials. Here, we develop a large-size ultralightweight artificial "wood nacre" with an ordered layer structure through a fast and scalable "mechanical/chemical mineralization and assembly" approach. The millimeter-thick artificial wooden nacre mimics the stratified construction of natural nacre, resulting in a bulk hybrid material that can achieve almost the same strength as natural nacre while consisting of only one-sixth of the total inorganic content of natural nacre. The specific strength and toughness of the artificial wooden nacre is even superior to engineering alloy materials (such as Cu and Fe). This approach represents an efficient strategy for the mass production of lightweight sustainable structural materials with high strength and toughness.

Processing Lignocellulose-Based Composites into an Ultrastrong Structural Material.

Natural lignocellulose has been a significant renewable raw material attributable to its high specific mechanical performance, compared to the benefits of traditional reinforcing fibers. However, the unsatisfactory mechanical performance of lignocellulose-based materials has limited applications in many advanced engineering domains. Herein, we demonstrate that layered bulk delignified nanolignocellulose/brushite composites with a multifold increase in strength and toughness. Our procedure contains the partially removable lignin and hemicellulose from the nanolignocellulose and the precipitating process of brushite on the nanolignocellulose surface via the mechanochemical process and flow-directed assembly followed by hot-pressing, resulting in the complete toppling of cell walls and the densification of the nanolignocellulose/brushite composites with highly ordered layered structures. This composite exhibits an ultrastrong specific strength 1.8-4.4 times higher than that of modified lignocellulose-based materials, which surpasses that of most natural structural materials and some metals and alloys, opening a path for production of ultrastrong lignocellulose-based load-bearing materials in practical applications by various farming and forestry surplus operations.

Author Correction: The properties of fibreboard based on nanolignocelluloses/CaCO3/PMMA composite synthesized through mechano-chemical method.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Ultrafine Mn ferrite by anchoring in a cellulose framework for efficient toxic ions capture and fast water/oil separation.

The serious agglomeration phenomenon of ultrafine nanoparticles is widespread, resulting in low utilization and poor performance of adsorbents in the scavenging of toxic ions. Herein, ultrafine MnFe2O4 (8-13 nm) are uniformly anchored onto the cellulose framework by fast hydrothermal and freeze-drying processes. The as-prepared super-hydrophilic MnFe2O4/cellulose aerogel (MCA) had a three-dimensional (3D) network structure with interconnected and forked fibrils, developed porous structure and high surface area. Combined with the adsorption-aggregation effect of cellulose and high surface activity of the low agglomerated ultrafine MnFe2O4, the adsorption efficiency of MCA was strongly improved and thus achieved a higher utilization. To enable its further use in a hostile environment for the treatment of severe oil pollution, FAS-17 was used to modify the MnFe2O4/cellulose aerogel (F-MCA) for achieving full utilization of their intrinsic structural features. The lipophilic F-MCA exhibited a large bearing capacity on the water and fast adsorption performance for oils/organic solvents.

The properties of fibreboard based on nanolignocelluloses/CaCO3/PMMA composite synthesized through mechano-chemical method.

The purpose of this study was to develop a rapid and green method for the synthesis of lignocelluloses-based materials with superior mechanical properties. Samples were produced by hot-pressed method using different concentrations of CaCO3 and poly (methyl methacrylate) particles-filled nanolignocelluloses composites which was synthesized through mechano-chemical method. Poly (methyl methacrylate) and CaCO3 nanoparticles have been used as nanofillers. Bending strength, elasticity modulus, and dimensional stability, thermal properties of the developed lignocelluloses-based composites were determined. In view of the experimental results, it is found that the composites materials have good mechanical, dimensional stability, and thermal properties which enhanced as the filler loading increased. Thus, herein described lignocelluloses-based materials showed important characteristics to be concluded that these composites are suitable to be used for the design of flooring and construction systems.

Effect of carbon fiber addition on the electromagnetic shielding properties of carbon fiber/polyacrylamide/wood based fiberboards.

Carbon fiber (CF) reinforced polyacrylamide/wood fiber composite boards are fabricated by mechanical grind-assisted hot-pressing, and are used for electromagnetic interference (EMI) shielding. CF with an average diameter of 150 nm is distributed on wood fiber, which is then encased by polyacrylamide. The CF/polyacrylamide/wood fiber (CPW) composite exhibits an optimal EMI shielding effectiveness (SE) of 41.03 dB compared to that of polyacrylamide/wood fiber composite (0.41 dB), which meets the requirements of commercial merchandise. Meanwhile, the CPW composite also shows high mechanical strength. The maximum modulus of rupture (MOR) and modulus of elasticity (MOE) of CPW composites are 39.52 MPa and 5823.15 MPa, respectively. The MOR and MOE of CPW composites increased by 38% and 96%, respectively, compared to that of polyacrylamide/wood fiber composite (28.64 and 2967.35 MPa).

High Mechanical Property of Laminated Electromechanical Sensors by Carbonized Nanolignocellulose/Graphene Composites.

Although widely used in nanocomposites, the effect of embedding graphene in carbonized nanolignocellulose substrates is less clear. We added graphene to a carbonized nanolignocellulose to change its mechanical and electromechanical properties. Here, the laminated carbonized nanolignocellulose/graphene composites were fabricated by carbonizing the nanolignocellulose/graphene composites prepared through mechanochemistry and flow-directed assembly process. The resulting composites exhibit excellent mechanical property with the ultimate bending strength of 25.6 ± 4.2 MPa. It is observed reversible electrical resistance change in these composites with strain, which is associated with the tunneling conduction model. This type of high-strength conductive composite has great potential applications in load-bearing electromechanical sensors.

Preparation of High Mechanical Performance Nano-Fe3O4/Wood Fiber Binderless Composite Boards for Electromagnetic Absorption via a Facile and Green Method.

Fe3O4/wood fiber composites are prepared with a green mechanical method using only distilled water as a solvent without any chemical agents, and then a binderless composite board with high mechanical properties is obtained via a hot-press for electromagnetic (EM) absorption. The fibers are connected by hydrogen bonds after being mechanically pretreated, and Fe3O4 nanoparticles (NPs) are attached to the fiber surface through physical adsorption. The composite board is bonded by an adhesive, which is provided by the reaction of fiber composition under high temperature and pressure. The Nano-Fe3O4/Fiber (NFF) binderless composite board shows remarkable microwave absorption properties and high mechanical strength. The optional reflection loss (RL) of the as-prepared binderless composite board is -31.90 dB. The bending strength of the NFF binderless composite board is 36.36 MPa with the addition of 6% nano-Fe3O4, the modulus of elasticity (MOE) is 6842.16 MPa, and the internal bond (IB) strength is 0.81 MPa. These results demonstrate that magnetic nanoparticles are deposited in binderless composite board by hot pressing, which is the easiest way to produce high mechanical strength and EM absorbers.

Fabrication of a Nano-ZnO/Polyethylene/Wood-Fiber Composite with Enhanced Microwave Absorption and Photocatalytic Activity via a Facile Hot-Press Method.

A polyethylene/wood-fiber composite loaded with nano-ZnO was prepared by a facile hot-press method and was used for the photocatalytic degradation of organic compounds as well as for microwave absorption. ZnO nanoparticles with an average size of 29 nm and polyethylene (PE) powders were dispersed on the wood fibers' surface through a viscous cationic polyacrylamide (CPAM) solution. The reflection loss (RL) value of the resulting composite was -21 dB, with a thickness of 3.5 mm in the frequency of 17.17 GHz. The PE/ZnO/wood-fiber (PZW) composite exhibited superior photocatalytic activity (84% methyl orange degradation within 300 min) under UV light irradiation. ZnO nanoparticels (NPs) increased the storage modulus of the PZW composite, and the damping factor was transferred to the higher temperature region. The PZW composite exhibited the maximum flexural strength of 58 MPa and a modulus of elasticity (MOE) of 9625 MPa. Meanwhile, it also displayed dimensional stability (thickness swelling value of 9%).

Utilizing cellulose sheets as structure promoter constructing different micro-nano titanate nanotubes networks for green water purification.

In this work, we provide a novel strategy of constructing different micro-nano structure (arrayed, multilevel, flower-like) titanate nanotubes (TNTs) networks with cellulose sheets as structure promoter. Through cellulose self-locking and inter-locking, several micro-nano TNTs networks with higher specific surface area are obtained and applied to toxic heavy metal Pb2+ cations removal. It not only makes abundant toxic Pb2+ ions exchange with the inter-layer Na+ ions of TNTs, but also allows many Pb2+ ions to be deposited onto the TNTs surface. As expected, heavy metal Pb2+ removal performance of the as-prepared TNTs networks miraculously reaches 5.24mmolg-1. Moreover, the prepared titanate network is also exhibited a good co-removal capacity of multi-component ions (Pb2+, Sr2+ and Cs+) and superior acid/alkali adaptability. Therefore, the as-fabricated TNTs network with cellulose sheets as structure promoter could be regarded as a promising water purifier.

Cellulose Fibers Constructed Convenient Recyclable 3D Graphene-Formicary-like δ-Bi2O3 Aerogels for the Selective Capture of Iodide.

Radioiodine is highly radioactive and acutely toxic, which can be a serious health threat, and requires effective control. To fully utilize an adsorbent and reduce the overall production cost, successive recycling applications become necessary. Here, 3D formicary-like δ-Bi2O3 (FL-δ-Bi2O3) aerogel adsorbents were synthesized using a one-pot hydrothermal method. In this hybrid structure, abundant flowerlike δ-Bi2O3 (MR-δ-Bi2O3) microspheres were inlaid into the interconnected ant nest channel, forming a 3D hierarchical structure, which is applied as an efficient adsorbent with easy recovery for radioiodine removal. Notably, the FL-δ-Bi2O3 aerogel adsorbent exhibited a very high uptake capacity of 2.04 mmol/g by forming an insoluble Bi4I2O5 phase. Moreover, the FL-δ-Bi2O3 worked in a wide pH range of 4-10 and displayed fast uptake kinetics and excellent selectivity due to the 3D porous interconnected network and larger specific surface area. Importantly, the recycling process is easy, using only tweezers to directly move the 3D aerogel adsorbents from one reaction system to another. Therefore, the FL-δ-Bi2O3 aerogel may be a promising practical adsorbent for the selective capture of radioactive iodide.

Bio-Inspired nacre-like nanolignocellulose-poly (vinyl alcohol)-TiO2 composite with superior mechanical and photocatalytic properties.

Nacre, the gold standard for biomimicry, provides an excellent example and guideline for assembling high-performance composites. Inspired by the layered structure and extraordinary strength and toughness of natural nacre, nacre-like nanolignocellulose/poly (vinyl alcohol)/TiO2 composites possessed the similar layered structure of natural nacre were constructed through hot-pressing process. Poly (vinyl alcohol) and TiO2 nanoparticles have been used as nanofillers to improve the mechanical performance and synchronously endow the superior photocatalytic activity of the composites. This research would be provided a promising candidate for the photooxidation of volatile organic compounds also combined with outstanding mechanical property.