Bioinspired Wood Nanotechnology for Functional Materials

Bioinspired wood-based wedge-shaped surface with gradient wettability for enhanced directional liquid transport and fog harvesting

Inspired by cactus spine and desert beetle back structures, we developed a wood-based wedge-shaped surface with gradient wettability for efficient and controlled spontaneous directional liquid transport. Utilizing the natural anisotropic and porous structure of wood, the wedge-shaped surface exhibited a continuous gradient wettability after chemical treatments combined with UV-induced modifications. The resulting surface enabled highly efficient directional liquid transport with transport rates reaching up to 8.9 mm s-1 on horizontal placement and 0.64 mm s-1 on vertical surfaces against gravity. By integrating geometric curvature and surface energy gradients, the innovative design achieved synergistic Laplace pressure-driven and wettability-driven liquid motions. To further demonstrate its potential for practical application, a fog-driven power device constructed using the gradient wettability wood with cactus spines not only enhanced water harvesting and energy conversion capabilities but also offered an environmentally friendly system. This study expanded the design toolbox for bioinspired liquid management surfaces, offering promising applications in water resource management, energy harvesting, and microfluidic devices.

Mechanically robust, flexible, conductive, and anti-freezing hydrogels reinforced by cellulose of wood skeleton

Hydrogels are soft and wet materials, but their applications are always limited by insufficient mechanical strength and toughness, and they are prone to freezing at low temperatures. In this study, we introduced an eco-friendly approach to developing wood-based hydrogels reinforced by the naturally aligned wood skeleton (WS) through the Hofmeister effect. The resulting wood-based composite hydrogels exhibited a high tensile strength of 20 MPa and a strain of 35 % in the longitudinal direction. This impressive mechanical performance was primarily due to densely packed hydrogen bonding, physical entanglements, and van der Waals forces between the cellulose of WS, polyacrylamide (PAM), and poly(vinyl alcohol) (PVA) chains during polymerization. Notably, the polymerization was induced using wood carbon dots as initiators, imparting additional fluorescence features to the hydrogels. Afterward, by incorporating a metal salt (sodium chloride), the developed wood-based hydrogels maintained high conductivity (3.0 S/m) and mechanical properties even under low-temperature conditions (-20 °C). Moreover, the conductive hydrogels exhibited multifunctional sensing capabilities, including strain, temperature, and ultraviolet (UV) irradiation detection, making them highly suitable for applications in human motion monitoring and healthcare, particularly under harsh environmental conditions.

Advanced wood-inorganic composites: preparation, properties and perspectives

In recent years, the widespread use of wood products has been observed in many fields. Wooden products have excellent green and environmentally friendly characteristics, but their performance often cannot meet people's needs. Many researchers have conducted in-depth research on wood-based composite materials and their modification methods in order to improve the performance of wood. This article provides a selective review of the types, modification methods, and properties of inorganic modifiers. The preparation methods are mainly divided into immersion methods, sol-gel methods, and hydrothermal synthesis. The flame retardancy, mechanical properties, hydrophobicity, and mold resistance of modified wood have been effectively improved. In addition, modified wood also has photoresponsive properties, electrical conductivity, and thermal conductivity. Finally, the challenges and perspectives on advanced wood-inorganic composites have been proposed for guiding future studies.

Bioinspired Durable Daytime Radiative Cooling Wood: Realizing Outdoor Longtime Use

Daytime radiative cooling dissipates heat from surfaces by reflecting sunlight and emitting infrared radiation to outer space, featuring zero-energy consumption. Wood-based coolers have received more attention due to their high infrared emissivity, sustainability, and low cost. However, they often degrade under ultraviolet (UV) radiation exposure, resulting in a poor cooling efficiency. Herein, inspired by the structure-functionality relationship in Saharan silver ants, an outdoor durable cooling wood (DCW) is developed that achieves excellent comprehensive performance via the assembly of the photonic structure of Mica@TiO2 on the structure of delignified wood, including both high solar reflectance (0.958), infrared emittance (0.95), mechanical strength (47 MPa), and UV resistance. The unique structure can prevent breaking of the C-O-C skeleton of wood under direct sunlight; the daytime cooling efficiency of DCW can maintain 4.5 °C after 720 h of UV exposure. This work paves the way for the development of durable daytime radiative cooling materials for energy savings.

Controllable synthesis of cypress-derived hard carbon for high-rate sodium ion storage

Optimized chemical pretreatment method facilitates the synthesis of biomass-based hard carbon with rich porosity at lower carbonization temps (900-1300 °C), yielding cost-effective and high-performance anode materials. The cypress-derived hard carbon (WC-1100) with hierarchical pores achieves a peak sodium ion storage of 307 mA h g-1 at 0.1 A g-1 with an impressive ICE of 82.5%.

A Bio-Inspired Perspective on Materials Sustainability

The article explores materials sustainability through a bio-inspired lens and discusses paradigms that can reshape the understanding of material synthesis, processing, and usage. It addresses various technological fields, from structural engineering to healthcare, and emphasizes natural material cycles as a blueprint for efficient recycling and reuse. The study shows that material functionality depends on both chemical composition and structural modifications, which emphasizes the role of material processing. The article identifies strategies such as mono-materiality and multifunctionality, and explores how responsivity, adaptivity, modularity, and cellularity can simplify material assembly and disassembly. Bioinspired strategies for reusing materials, defect tolerance, maintenance, remodeling, and healing may extend product lifespans. The principles of circularity, longevity, and parsimony are reconsidered in the context of "active materiality", a dynamic bio-inspired paradigm. This concept expands the traditional focus of material science from structure-function relationships to include the development of materials capable of responding or adapting to external stimuli. Concrete examples demonstrate how bio-inspired strategies are being applied in engineering and technology to enhance the sustainability of materials. The article concludes by emphasizing interdisciplinary collaboration as a key factor for developing a sustainable and resilient materials economy in harmony with nature's material cycles.

Hijacking plant skeletons for biomedical applications: from regenerative medicine and drug delivery to biosensing

The field of biomedical engineering continually seeks innovative technologies to address complex healthcare challenges, ranging from tissue regeneration to drug delivery and biosensing. Plant skeletons offer promising opportunities for these applications due to their unique hierarchical structures, desirable porosity, inherent biocompatibility, and adjustable mechanical properties. This review comprehensively discusses chemical principles underlying the utilization of plant-based scaffolds in biomedical engineering. Highlighting their structural integrity, tunable properties, and possibility of chemical modification, the review explores diverse preparation strategies to tailor plant skeleton properties for bone, neural, cardiovascular, skeletal muscle, and tendon tissue engineering. Such applications stem from the cellulosic three-dimensional structure of different parts of plants, which can mimic the complexity of native tissues and extracellular matrices, providing an ideal environment for cell adhesion, proliferation, and differentiation. We also discuss the application of plant skeletons as carriers for drug delivery due to their structural diversity and versatility in encapsulating and releasing therapeutic agents with controlled kinetics. Furthermore, we present the emerging role played by plant-derived materials in biosensor development for diagnostic and monitoring purposes. Challenges and future directions in the field are also discussed, offering insights into the opportunities for future translation of sustainable plant-based technologies to address critical healthcare needs.

Tailoring anisotropic ZnO/wood-structural holocellulose hybrids for dye degradation through controlled nanoinsertion

Nanostructured inorganic/wood-structural holocellulose hybrids offer new potential applications, including mechanical energy conversion, superhydrophobic materials, gas adsorption and so on. Owing to the anisotropy of wood, controlling the morphology of mineral particles inside porous holocellulose scaffold is still far from satisfactory. In this work, a homogeneous zinc oxide (ZnO) decoration inside wood-structural holocellulose scaffold was achieved while the morphology, distribution and content of ZnO micro-nano particles were controllable through changing the conditions of hydrothermal growth. The holocellulose scaffold was prepared through delignification and periodate oxidation, which is favorable for Zn2+ capture and ZnO nuclei formation because of the surface charge increased. The controlled ZnO insertion was realized by changing metal salt concentration, temperature and hydrothermal time. The obtained multilayer ZnO could provide multiple light refractions and reflections and enhance the utilization of light. Consequently, with a minor ZnO loading (15 wt%), the ZnO/wood-structural hybrids could totally degrade methyl orange and methyl blue in 6 h. This novel and scalable synthesis method shows potential for both the design and photocatalytic activity of holocellulose hybrids.

Cellulose-Templated Nanomaterials for Nanogenerators and Self-Powered Sensors

Energy crisis inspires the development of renewable and clean energy sources, along with related applications such as nanogenerators and self-powered devices. Balancing high performance and environmental sustainability in advanced material innovation is a challenging task. Addressing the global challenges of sustainable development and carbon neutrality lead to increased interest in biopolymer research. Nanocellulose materials, derived from biopolymers, demonstrate potential as template candidates for advanced materials, due to their unique properties, including high strength, high surface area, controllable pore structures and high-water retention. In recent years, cellulose-templated nanomaterials enable delicate nano-/microscale structural construction, thus promoting developments in the field of nanogenerators and self-powered sensors. However, there is still a limited number of reviews focused on cellulose-templated nanomaterials for applications in nanogenerators and self-powered sensors. This review aims to fill this research gap by introducing various cellulose-templated nanomaterials and providing a detailed analysis of their fashionable applications in nanogenerators and self-powered sensors. The goal is to present cellulose-templated nanomaterials as highly promising template and guest materials for templating technologies, offering sustainable nano-/microscale control over advanced materials for the foreseeable future. This potential is promising for new applications in the fields of nanogenerators and self-powered sensors.

A Hydrogel-coated Wood Membrane with Intelligent Oil Pollution Detection for Emulsion Separation

Considering the potential threats posed by oily wastewater to the ecosystem, it is urgently in demand to develop efficient, eco-friendly, and intelligent oil/water separation materials to enhance the safety of the water environment. Herein, an intelligent hydrogel-coated wood (PPT/PPy@DW) membrane with self-healing, self-cleaning, and oil pollution detection performances is fabricated for the controllable separation of oil-in-water (O/W) emulsions and water-in-oil (W/O) emulsions. The PPT/PPy@DW is prepared by loading polypyrrole (PPy) particles on the delignified wood (DW) membranes, further modifying the hydrogel layer as an oil-repellent barrier. The layered porous structure and selective wettability endow PPT/PPy@DW with great separation performance for various O/W emulsions (≥98.69% for separation efficiency and ≈1000 L m-2 h-1 bar-1 for permeance). Notably, the oil pollution degree of PPT/PPy@DW can be monitored in real-time based on the changed voltage generated during O/W emulsion separation, and the oil-polluted PPT/PPy@DW can be self-cleaned by soaking in water to recover its separation performance. The high affinity of PPT/PPy@DW for water makes it effective in trapping water from the mixed surfactant-stabilized W/O emulsions. The prepared eco-friendly and low-cost multifunctional hydrogel wood membrane shows promising potential in on-demand oil/water separation and provides new ideas for the functional improvement of new biomass oil/water separation membrane materials.

Kilogram-scale production of strong and smart cellulosic fibers featuring unidirectional fibril alignment

Multifunctional fibers with high mechanical strength enable advanced applications of smart textiles, robotics, and biomedicine. Herein, we reported a one-step degumming method to fabricate strong, stiff, and humidity-responsive smart cellulosic fibers from abundant natural grass. The facile process involves partially removing lignin and hemicellulose functioning as glue in grass, which leads to the separation of vessels, parenchymal cells, and cellulosic fibers, where cellulosic fibers are manufactured at kilogram scale. The resulting fibers show dense and unidirectional fibril structure at both micro- and nano-scales, which demonstrate high tensile strength of ∼0.9 GPa and Young's modulus of 72 GPa, being 13- and 14-times higher than original grass. Inspired by stretchable plant tendrils, we developed a humidity-responsive actuator by engineering cellulosic fibers into the spring-like structures, presenting superior response rate and lifting capability. These strong and smart cellulosic fibers can be manufactured at large scale with low cost, representing promising a fiber material derived from renewable and sustainable biomass.

Lightweight, Strong, and Transparent Wood Films Produced by Capillary Driven Self-Densification

Wood delignification and densification enable the production of high strength and/or transparent wood materials with exceptional properties. However, processing needs to be more sustainable and besides the chemical delignification treatments, energy intense hot-pressing calls for alternative approaches. Here, this study shows that additional softening of delignified wood via a mild swelling process using an ionic liquid-water mixture enables the densification of tube-line wood cells into layer-by-layer sheet structures without hot-pressing. The natural capillary force induces self-densification in a simple drying process resulting in a transparent wood film. The as-prepared films with ≈150 µm thickness possess an optical transmittance ≈70%, while maintaining optical haze >95%. Due to the densely packed sheet structure with a large interfacial area, the reassembled wood film is fivefold stronger and stiffer than the delignified wood in fiber direction. Owing to a low density, the specific tensile strength and elastic modulus are as high as 282 MPa cm3 g-1 and 31 GPa cm3 g-1. A facile and highly energy efficient wood nanotechnology approach are demonstrated toward more sustainable materials and processes by directly converting delignified wood into transparent wood omitting polymeric matrix infiltration or mechanical pressing.

Design and Construction of Highly Luminescent Transparent Woody Materials Exhibiting Unique Fluorescence-Enhanced Staining Effects for Visualization of Intrinsic Microporous Networks

Luminescent wood materials are an emerging class of biomass hybrid host materials owing to the hierarchical porous structure and functionalization versatility. The fluorescence properties are largely dependent on exogenous fluorophores, which are, however, often plagued by notorious aggregation effects. In this work, an efficient strategy for the preparation of luminescent transparent wood materials is developed by incorporating tetraphenylethylene-derived aggregation-induced emission (AIE)-active fluorophores during a delignification-backfill transparency process. These wood hybrids showed unexpected luminescence enhancement that significantly increased the fluorescence quantum yield of the fluorophores up to 99%, much higher than that of the fluorophores in other states such as crystalline solids or doped in a polymer substrate. Mechanistic investigations reveal that in situ polymerization of prepolymerized methyl methacrylate in delignified microporous wood frames produces high molecular weight ordered PMMA polymers, resulting in a rigid molecular environment that improves the luminescence efficiency of TPE-based fluorophores at the interfaces of PMMA polymer and cell walls. By confocal laser scanning microscopy (CLSM), this excellent fluorescence staining capability was furthermore utilized to visualize the intrinsic porous network of wood in three dimensions over a large volume with submicrometer resolution, thus providing an alternative approach to the study of structure-function relationships in such wood hybrids.

Effect of environmental factors on adsorption of ciprofloxacin from wastewater by microwave alkali modified fly ash

Antibiotics, as emerging persistent pollutants, pose significant threats to human health. The effective and low-cost removal of ciprofloxacin (CIP) from wastewater has become an important research focus. In this study, fly ash (FA) was used as the raw material, and modified fly ash (MFA) was prepared by varying microwave power, alkali concentration, and immersion time to investigate its adsorption characteristics for CIP. Results showed that the optimal preparation conditions for MFA with the most effective adsorption of CIP, using the Box-Behnken response surface methodology, were a microwave power of 480 W, an alkali concentration of 1.5 mol/L, and a modification time of 3 h. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analyses revealed that after modification, the glassy structure of FA is destroyed, the specific surface area is increased, and obvious hydroxyl O-H absorption peaks appear. Both FA and MFA exhibited adsorption processes for CIP that conformed to pseudo-second-order kinetics and the Langmuir equation. Maximum adsorption of CIP (9.61 and 12.67 mg/g) was achieved at pH = 6. With increasing temperature, the adsorption capacity of both FA and MFA for CIP decreased, indicating an exothermic process. The adsorption capacity of CIP decreased with increasing ion concentration, with the impact order of ions being Al3+  > Ca2+  > Na+. The results show that pore filling, electrostatic interaction, ion exchange and complexation are the main ways of CIP adsorption by FA. Microwave alkali modified fly ash is an economical and efficient adsorbent for CIP removal in water, realizing the purpose of "treating waste with waste". This study provides a scientific basis for controlling CIP treatment in wastewater.

A review on intelligence of cellulose based materials

Cellulose based materials are widely used in various fields such as papermaking, packaging, composite materials, textiles and clothing due to their diverse types, environmental friendliness, natural degradation, high specific strength, and low cost. The intelligence of cellulose based materials will further expand their application fields. This article first gives an in-depth analyzation on the intelligent structural design of these materials according to the two major categories of isotropic and anisotropic, then lists the main preparation methods of cellulose based intelligent materials. Subsequently, this article systematically summarizes the recent intelligent response methods and characteristics of cellulose based materials, and extensively elaborates on the intelligent application of these materials. Finally, the prospects for the intelligence of cellulose based materials are discussed.

A comprehensive review on preparation and functional application of the wood aerogel with natural cellulose framework

As the traditional aerogel has defects such as poor mechanical properties, complicated preparation process, high energy consumption and non-renewable, wood aerogel as a new generation of aerogel shows unique advantages. With a natural cellulose framework, wood aerogel is a novel nano-porous material exhibiting exceptional properties such as light weight, high porosity, large specific surface area, and low thermal conductivity. Furthermore, its adaptability to further functionalization enables versatile applications across diverse fields. Driven by the imperative for sustainable development, wood aerogel as a renewable and eco-friendly material, has garnered significant attention from researchers. This review introduces preparation methods of wood aerogel based on the top-down strategy and analyzes the factors influencing their key properties intending to obtain wood aerogels with desirable properties. Avenues for realizing its functionality are also explored, and research progress across various domains are surveyed, including oil-water separation, conductivity and energy storage, as well as photothermal conversion. Finally, potential challenges associated with wood aerogel exploitation and utilization are addressed, alongside discussions on future prospects and research directions. The results emphasize the broad research value and future prospects of wood aerogels, which are poised to drive high-value utilization of wood and foster the development of green multifunctional aerogels.

Superstrong, sustainable, origami wood paper enabled by dual-phase nanostructure regulation in cell walls

Constructing a crystalline-amorphous hybrid structure is an effective strategy to overcome the conflict between the strength and toughness of materials. However, achieving such a material structure often involves complex, energy-intensive processing. Here, we leverage the natural wood featuring coexisting crystalline and amorphous regions to achieve superstrong and ultratough wood paper (W-paper) via a dual-phase nanostructure regulation strategy. After partially removing amorphous hemicellulose and eliminating most lignin, the treated wood can self-densify through an energy-efficient air drying, resulting in a W-paper with high tensile strength, toughness, and folding endurance. Coarse-grained molecular dynamics simulations reveal the underlying deformation mechanism of the crystalline and amorphous regions inside cell walls and the failure mechanism of the W-paper under tension. Life cycle assessment reveals that W-paper shows a lower environmental impact than commercial paper and common plastics. This dual-phase nanostructure regulation based on natural wood may provide valuable insights for developing high-performance and sustainable film materials.

Controlled Interlayer Binding and Healing Improve the Transverse Properties of Upcycled Disposable Waste Wood

Recovery and reuse of bulk waste wood are particularly challenging because of usage defects and contaminations. Here, we present a robust and efficient strategy for regenerating used wood veneers into high-performance structural materials through micro/nano interface manipulation. Our approach involves using cellulose-based interlayers to bind together two waste wood plates without an external adhesive by partially dissolving and regenerating the interlayer using a solution of ionic liquids and dimethyl sulfoxide. The mechanical properties of the regenerated wood exceed that of natural wood, displaying over a 16 and 20 times increase in transverse tensile strength and modulus, respectively, and 4-6 times improvement in longitudinal tensile strength and modulus. Nanoscale mechanical analyses show that the improvement is possible as a result of several factors, including the robust network structure of the interlayer, the good adhesion at the wood-interlayer interface, the compacted wood structure, and the low stiffness and deformation gradients between the interlayer and the wood structure. The interlayers can be created from waste papers and wood particles by taking advantage of the nanofibrillar structure of cellulose.

Functionalised Fibres as a Coupling Reinforcement Agent in Recycled Polymer Composites

This study addresses the structure-property relationship within the green concept of wood fibres with cellulose nanofibre functionalised composites (nW-PPr) containing recycled plastic polyolefins, in particular, polypropylene (PP-r). It focuses especially on the challenges posed by nanoscience in relation to wood fibres (WF) and explores possible changes in the thermal properties, crystallinity, morphology, and mechanical properties. In a two-step methodology, wood fibres (50% wt%) were first functionalised with nanocellulose (nC; 1-9 wt%) and then, secondly, processed into composites using an extrusion process. The surface modification of nC improves its compatibility with the polymer matrix, resulting in improved adhesion, mechanical properties, and inherent biodegradability. The effects of the functionalised WF on the recycled polymer composites were investigated systematically and included analyses of the structure, crystallisation, morphology, and surface properties, as well as thermal and mechanical properties. Using a comprehensive range of techniques, including X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), zeta potential measurements, and dynamic mechanical analysis (DMA), this study aims to unravel the intricate interplay of factors affecting the performance and properties of the developed nanocellulose-functionalised wood fibre-polymer composites. The interfacial adhesion of the nW-PPr polymer composites, crystallisation process, and surface properties was improved due to the formation of an H-bond between the nW coupling agent and neat PP-r. In addition, the role of nW (1.0 wt%) as a nucleating agent resulted in increased crystallinity, or, on the other hand, promoted the interfacial interaction with the highest amount (3.0% wt%, 9.0% wt%) of nW in the PP-r preferentially between the nW and neat PP-r, and also postponed the crystallisation temperature. The changes in the isoelectric point of the nW-PPr polymer composites compared to the neat PP-r polymer indicate the acid content of the polymer composite and, consequently, the final surface morphology. Finally, the higher storage modulus of the composites compared to neat r-PP shows a dependence on improved crystallinity, morphology, and adhesion. It was clear that the results of this study contribute to a better understanding of sustainable materials and can drive the development of environmentally friendly composites applied in packaging.

Polymeric monolithic columns based on natural wood for rapid purification of targeted protein

With multiscale hierarchical structure, wood is suitable for a range of high-value applications, especially as a chromatographic matrix. Here, we have aimed to provide a weak anion-exchange polymeric monolithic column based on natural wood with high permeability and stability for effectively separating the targeted protein. The wood-polymeric monolithic column was synthesized by in situ polymerization of glycidyl methacrylate and ethylene glycol dimethacrylate in wood, and coupled with diethylaminoethyl hydrochloride. The wood-polymeric monolithic column can be integrated with fast-protein liquid chromatography for large-scale protein purification. According to the results, the wood-polymeric monolithic column showed high hydrophilicity, permeability and stability. Separation experiments verified that the wood-polymeric monolithic column could purify the targeted protein (spike protein of SARS-COV-2 and ovalbumin) from the mixed proteins by ion exchange, and the static adsorption capacity was 33.04 mg mL-1 and the dynamic adsorption capacity was 24.51 mg mL-1. In addition, the wood-polymerized monolithic column had good stability, and a negligible decrease in the dynamic adsorption capacity after 20 cycles. This wood-polymerized monolithic column can provide a novel, efficient, and green matrix for monolithic chromatographic columns.

A Top-Down Approach to the Fabrication of Flame-Retardant Wood Aerogel with In Situ-Synthesized Borax and Zinc Borate

In this study, a top-down approach was employed for the fabrication of flame-retardant wood aerogels. The process involved the removal of lignin and the removal of hemicellulose utilizing NaOH concomitantly with the incorporation of ZnO and urea. Subsequently, an in situ reaction with boric acid was conducted to prepare flame-retardant wood aerogels. The morphology, chemical composition, thermal stability, and flame retardancy of the samples were studied. The results show that the NaOH treatment transformed the wood into a layered structure, and flame-retardant particles were uniformly distributed on the surface of the aerogel. The peak heat release rate (PHRR) and total heat release (THR) of the flame-retardant aerogel were significantly reduced compared with the control samples. Meanwhile, its vertical burning test (UL-94) rating reached the V-0 level, and the Limiting Oxygen Index (LOI) could exceed 90%. The flame-retardant wood aerogel exhibited excellent flame retardancy and self-extinguishing properties.

Leakage Proof, Flame-Retardant, and Electromagnetic Shield Wood Morphology Genetic Composite Phase Change Materials for Solar Thermal Energy Harvesting

Phase change materials (PCMs) offer a promising solution to address the challenges posed by intermittency and fluctuations in solar thermal utilization. However, for organic solid-liquid PCMs, issues such as leakage, low thermal conductivity, lack of efficient solar-thermal media, and flammability have constrained their broad applications. Herein, we present an innovative class of versatile composite phase change materials (CPCMs) developed through a facile and environmentally friendly synthesis approach, leveraging the inherent anisotropy and unidirectional porosity of wood aerogel (nanowood) to support polyethylene glycol (PEG). The wood modification process involves the incorporation of phytic acid (PA) and MXene hybrid structure through an evaporation-induced assembly method, which could impart non-leaking PEG filling while concurrently facilitating thermal conduction, light absorption, and flame-retardant. Consequently, the as-prepared wood-based CPCMs showcase enhanced thermal conductivity (0.82 W m-1 K-1, about 4.6 times than PEG) as well as high latent heat of 135.5 kJ kg-1 (91.5% encapsulation) with thermal durability and stability throughout at least 200 heating and cooling cycles, featuring dramatic solar-thermal conversion efficiency up to 98.58%. In addition, with the synergistic effect of phytic acid and MXene, the flame-retardant performance of the CPCMs has been significantly enhanced, showing a self-extinguishing behavior. Moreover, the excellent electromagnetic shielding of 44.45 dB was endowed to the CPCMs, relieving contemporary health hazards associated with electromagnetic waves. Overall, we capitalize on the exquisite wood cell structure with unidirectional transport inherent in the development of multifunctional CPCMs, showcasing the operational principle through a proof-of-concept prototype system.

Fabrication of bulk superhydrophobic wood by grafting porous poly(divinylbenzene) to wood structure using isocyanatoethyl methacrylate

Superhydrophobic treatment of wood can effectively reduce the interaction between wood and moisture, avoiding deformation, cracking, mould, and other defects caused by water absorption, which can extend the service life of wood and broaden the application field. Currently, the poor abrasion resistance of superhydrophobic wood is a crucial problem limiting its widespread application, and the preparation of superhydrophobic wood with robustness, abrasion resistance, and chemical resistance remains a huge challenge. In this work, robust bulk superhydrophobic wood with excellent abrasion resistance and chemical durability was fabricated by synthesizing porous poly(divinylbenzene) in wood cell cavities using graft copolymerization and solvothermal methods. The contact angles and rolling angles on the superhydrophobic wood surface were approximately 156° and 3°, respectively. Superhydrophobicity was carried through the entire structure of the wood. Even after severe damage by abrasion and sawing, as well as tests with organic solvents and harsh environments, the superhydrophobic properties of wood remained stable. Meanwhile, the superhydrophobic wood exhibited great self-cleaning and antifouling properties. In addition, the water uptake and dimensional stability of the wood were significantly improved. This work developed a simple, efficient, and durable strategy for the fabrication of superhydrophobic wood with robustness, abrasion resistance, and chemical resistance, which was expected to be applied to the wood industry to achieve the high-value applications of wood products and extend their service life.

A Wooden Carbon-Based Photocatalyst for Water Treatment

Due to a large number of harmful chemicals flowing into the water source in production and life, the water quality deteriorates, and the use value of water is reduced or lost. Biochar has a strong physical adsorption effect, but it can only separate pollutants from water and cannot eliminate pollutants fundamentally. Photocatalytic degradation technology using photocatalysts uses chemical methods to degrade or mineralize organic pollutants, but it is difficult to recover and reuse. Woody biomass has the advantages of huge reserves, convenient access and a low price. Processing woody biomass into biochar and then combining it with photocatalysts has played a complementary role. In this paper, the shortcomings of a photocatalyst and biochar in water treatment are introduced, respectively, and the advantages of a woody biochar-based photocatalyst made by combining them are summarized. The preparation and assembly methods of the woody biochar-based photocatalyst starting from the preparation of biochar are listed, and the water treatment efficiency of the woody biochar-based photocatalyst using different photocatalysts is listed. Finally, the future development of the woody biochar-based photocatalyst is summarized and prospected.

Impact of surface delignification on fire retardancy of wood treated with polyelectrolyte complexes

Wood is a natural composite widely employed as a residential building interior finishing. Although wood is readily available and offers benefits to the occupants, such as enhanced well-being, it is rarely employed in commercial construction due, amongst others, to the potential hazard of fire propagation. The application of flame retardant (FR) treatments leads to a reduction of wood flammability and supports wood as interior finishing. Polyelectrolyte complexes (PECs) deposition is an innovative surface treatment that has already proven its efficiency for fabrics. For wood, recent studies have highlighted that the weight gain impacted the fire-retardancy, and a minimum of 2 wt.-% was set to obtain fire protection. This study explored the potential of surface delignification to activate the wood surface and facilitate the PEC impregnation. Yellow birch (Betula alleghaniensis, Britt.) was surface delignified (0.3 mm) using sodium chlorite. The treatment impact on wood was evaluated by spectroscopy analysis (FTIR, Raman), and the increase in wood wettability was demonstrated (contact angle decreases from 50° to 35° after the surface delignification). Then, PECs consisting of polyethyleneimine and sodium phytate were surface impregnated in wood and delignified wood. The flame retardancy was evaluated using a cone calorimeter. Despite the increase in weight gain (1.5 wt.-% ± 0.3 wt.-% to 4.3 wt.-% ± 2.5 wt.-%), fire performance was not improved. This study demonstrates that lignin strongly affects char formation, even in the presence of PECs.

Fabrication and characterization of flexible natural cellulosic fiber composites through collaborative modification strategy of sodium hydroxide and γ-Aminopropyl triethoxysilane

The primary purpose of this work is to study the fabrication of a flexible natural cellulosic fiber composite. In this respect, natural cellulosic fiber was obtained by modified poplar wood fiber through sodium hydroxide (NaOH) and γ-Aminopropyl Triethoxysilan. Then, the composites were fabricated by hot-pressing the modified wood fibers and polyurethane following characterization. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) observation results confirmed that some of the hemicellulose and lignin were removed from wood fibers after NaOH modification and successfully grafted with alkoxy structures after KH550 modification. NaOH&KH550 modification improved the interfacial compatibility between poplar wood fibers and polyurethane. The flexibility of the composites was improved (the slenderness value was reduced by 113 %), allowing flexible deformations such as bending, twisting, and knotting. In addition, thermal stability, tensile strength (increased by 105 %), elongation at the break (increased by 125 %), and water resistance were increased. This flexible natural cellulosic fiber composite is expected to be applied in the veneering of curved materials and special-shaped structure furniture, providing a theoretical basis for improving the added value of wood-based composites.

Facile and Widely Applicable Route to Self-Adaptive Emissivity Modulation: Energy-Saving Demonstration with Transparent Wood

The cooling power provided by radiative cooling is unwanted during cold hours. Therefore, self-adaptive regulation is desired for radiative cooling, especially in all-weather applications. However, current routes for radiative cooling regulation are constrained by substrates and complicated processing. Here, self-adaptive radiative cooling regulation on various potential substrates (transparent wood, PET, normal glass, and cement) was achieved by a Fabry-Perot structure consisting of a silver nanowires (AgNWs) bottom layer, PMMA spacer, and W-VO2 top layer. The emissivity-modulated transparent wood (EMTW) exhibits an emissivity contrast of 0.44 (ε8-13-L = ∼0.19 and ε8-13-H = ∼0.63), which thereby yields considerable energy savings across different climate zones. The emissivity contrast can be adjusted by varying the spinning parameters during the deposition process. Positive emissivity contrast was also achieved on three other industrially relevant substrates via this facile and widely applicable route. This proves the great significance of the approach to the promotion and wide adoption of radiative cooling regulation concept in the built environment.

Target-modulated mineralization of wood channels as enzyme-free electrochemical sensors for detecting amyloid-β species

Alzheimer's disease (AD) is an irreversible brain disorder, which has been found to be associated with neurotoxic amyloid-β oligomers (AβO). The early diagnosis of AD is still a great challenge. Herein, inspired by the hierarchical channel structure of natural wood, we design and demonstrate a low-cost and sensitive wood channel-based fluidic membrane for electrochemical sensing of AβO1-42. In this design, Zn/Cu-2-methylimidazole (Zn/Cu-Hmim) with artificial peroxidase (POD)-like activity was asymmetrically fabricated at one side of the wood channels by biomimetic mineralization and a subsequent ion exchange reaction. The strong affinity between Cu(II) and AβO1-42 enables Cu(II) species in Zn/Cu-Hmim to be extracted by AβO1-42, thus suppressing the POD-like performance via Zn/Cu-Hmim disassembly. Using Zn/Cu-Hmim to catalyze the oxidation reaction of 2,2'-diazo-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) by H2O2, the current-voltage (I-V) properties of wood channels are influenced by the generated oxidation product (ABTS•+), thus providing information useful for the quantitative analysis of AβO1-42. Importantly, the three aggregation states of Aβ1-42 (AβM1-42, AβO1-42, and AβF1-42) can also be identified, owing to the affinity difference and available reaction sites. The proposed wood membrane provides a novel, assessable, and scalable channel device to develop sensitive electrochemical sensors; moreover, the sustainable wood materials represent alternative candidates for developing channel-structured sensing platforms.

Green synthesis of metal-organic framework loaded dexamethasone on wood aerogels for enhanced cranial bone regeneration

Bone defects have attracted increasing attention in clinical settings. To date, there have been no effective methods to repair defective bones. Balsa wood aerogels are considered as an excellent source of chemicals for chemical modification to facilitate the in situ immobilization of zeolitic imidazolate framework-8. Furthermore, dexamethasone has received considerable attention for bone tissue engineering. In this study, for the first time, a simple but effective one-pot method for developing a novel zeolitic imidazolate framework-8 with different concentrations of dexamethasone was developed. These findings illustrate that the novel scaffold has a significant positive impact on osteogenic differentiation in vitro and repairs defects in vivo, suggesting that it can be used in bone tissue engineering.

Redesigning Natural Materials for Energy, Water, Environment, and Devices

The United Nations Framework Convention on Climate Change (UNFCCC) acknowledges that global cooperation is paramount to mitigate climate change and further warming. The global community is committed to renewable energy and natural materials to tackle this challenge for all humankind. The widespread use of natural materials is embraced as one such action to reach net-zero carbon emissions. Given the hierarchical framework and earth abundance, cellulose-based materials extend their negative carbon benefits to our daily products and accelerate our pace toward carbon neutrality. Here, we present an overview of recent developments of cellulose-based materials in upsurging applications in radiative cooling, thermal insulation, nanofluidics, and wearable devices. We also highlight various modifications and functionalized processes that transform massive amounts of cellulose into green products. The prosperous development of functionalized cellulose materials aligns with a circular economy. Expedited interdisciplinary fundamental investigations are expected to make fibrillated cellulose penetrate more into carbon downdraw at speed and scale.

Revealing the closed pore formation of waste wood-derived hard carbon for advanced sodium-ion battery

Although the closed pore structure plays a key role in contributing low-voltage plateau capacity of hard carbon anode for sodium-ion batteries, the formation mechanism of closed pores is still under debate. Here, we employ waste wood-derived hard carbon as a template to systematically establish the formation mechanisms of closed pores and their effect on sodium storage performance. We find that the high crystallinity cellulose in nature wood decomposes to long-range carbon layers as the wall of closed pore, and the amorphous component can hinder the graphitization of carbon layer and induce the crispation of long-range carbon layers. The optimized sample demonstrates a high reversible capacity of 430 mAh g-1 at 20 mA g-1 (plateau capacity of 293 mAh g-1 for the second cycle), as well as good rate and stable cycling performances (85.4% after 400 cycles at 500 mA g-1). Deep insights into the closed pore formation will greatly forward the rational design of hard carbon anode with high capacity.

Insulative Biobased Glaze from Wood Laminates Obtained by Self-Adhesion

The combination of optical transparency and mechanical strength is a highly desirable attribute of wood-based glazing materials. However, such properties are typically obtained by impregnation of the highly anisotropic wood with index-matching fossil-based polymers. In addition, the presence of hydrophilic cellulose leads to a limited water resistance. Herein, this work reports on an adhesive-free lamination that uses oxidation and densification to produce transparent all-biobased glazes. The latter are produced from multilayered structures, free of adhesives or filling polymers, simultaneously displaying high optical clarity and mechanical strength, in both dry and wet conditions. Specifically, high values of optical transmittance (≈85.4%), clarity (≈20% with low haze) at a thickness of ≈0.3 mm, and highly isotropic mechanical strength and water resistance (wet strength of ≈128.25 MPa) are obtained for insulative glazes exhibiting low thermal conductivity (0.27 W m-1 K-1 , almost four times lower than glass). The proposed strategy results in materials that are systematically tested, with the leading effects of self-adhesion induced by oxidation rationalized by ab initio molecular dynamics simulation. Overall, this work demonstrates wood-derived materials as promising solutions for energy-efficient and sustainable glazing applications.

Flowthrough Capture of Microplastics through Polyphenol-Mediated Interfacial Interactions on Wood Sawdust

Nano-/microplastics accumulate in aquatic bodies and raise increasing threats to ecosystems and human health. The limitation of existing water cleanup strategies, especially in the context of nano-/microplastics, primarily arises from their complexity (morphological, compositional, and dimensional). Here, highly efficient and bio-based flowthrough capturing materials (bioCap) are reported to remove a broad spectrum of nano-/microplastics from water: polyethylene terephthalate (anionic, irregular shape), polyethylene (net neutral, irregular shape), polystyrene (anionic and cationic, spherical shape), and other anionic and spherical shaped particles (polymethyl methacrylate, polypropylene, and polyvinyl chloride). Highly efficient bioCap systems that adsorb the ubiquitous particles released from beverage bags are demonstrated. As evidence of removal from drinking water, the in vivo biodistribution of nano-/microplastics is profiled, confirming a significant reduction of particle accumulation in main organs. The unique advantage of phenolic-mediated multi-molecular interactions is employed in sustainable, cost-effective, and facile strategies based on wood sawdust support for the removal of challenging nano-/microplastics pollutions.

Three-dimensional porous wood monolithic columns for efficient purification of spike glycoprotein of SARS-CoV-2

Considerable research has been devoted to finding a cost-effective chromatographic matrix with efficient adsorption and high throughput. Wood exhibits complex micro-network structures that make it a powerful contender for a novel environment-friendly chromatographic matrix material. We demonstrate a novel strategy to manufacture a wood monolithic column, which chemically modified the wood and imported diethyl aminoethyl, diethylamine, and amino groups. This wood monolithic column can maintain fully monolithic column performances and highly selective to spike glycoprotein of SARS-CoV-2 by ion exchange force. The wood monolithic column was evaluated by static adsorption, dynamic adsorption, and frontal analysis. The results showed that the static adsorption capacity of the wood monolithic column with 2-diethylaminoethylchloride hydrochloride for bovine serum albumin was 14.72 mg/g, and the adsorption process was chemisorption. In addition, it retained 80 % adsorption capacity after 110 repeated adsorption-elution cycles.

Ectopic callose deposition into woody biomass modulates the nano-architecture of macrofibrils

Plant biomass plays an increasingly important role in the circular bioeconomy, replacing non-renewable fossil resources. Genetic engineering of this lignocellulosic biomass could benefit biorefinery transformation chains by lowering economic and technological barriers to industrial processing. However, previous efforts have mostly targeted the major constituents of woody biomass: cellulose, hemicellulose and lignin. Here we report the engineering of wood structure through the introduction of callose, a polysaccharide novel to most secondary cell walls. Our multiscale analysis of genetically engineered poplar trees shows that callose deposition modulates cell wall porosity, water and lignin contents and increases the lignin-cellulose distance, ultimately resulting in substantially decreased biomass recalcitrance. We provide a model of the wood cell wall nano-architecture engineered to accommodate the hydrated callose inclusions. Ectopic polymer introduction into biomass manifests in new physico-chemical properties and offers new avenues when considering lignocellulose engineering.

In-situ magnetite deposited wood composites with extensive electromagnetic interference shielding performance

Wood is an insulator material, using its porous structure to endow it with efficient microwave absorption and broaden its application range is still a major challenge. Here, wood-based Fe₃O₄ composites with excellent microwave absorption properties and high mechanical strength were prepared by alkaline sulfite method, in-situ co-precipitation method and compression densification method. The results showed that the magnetic Fe₃O₄ was densely deposited in the wood cells, and the prepared wood-based microwave absorption composites had both high electrical conductivity, magnetic loss, excellent impedance matching performance and attenuation performance, as well as effective microwave absorption properties. In the frequency range of 2-18 GHz, the minimum reflection loss value was -25.32 dB. At the same time, it had high mechanical properties. Compared with the untreated wood, its modulus of elasticity (MOE) in bending increased by 98.77%, and modulus of rapture (MOR) in bending improved by 67.9%. The developed wood-based microwave absorption composite is expected to be used in electromagnetic shielding fields such as anti-radiation and anti-interference.

Algal-based wood as a green and sustainable alternative for environmentally friendly & flexible electronic devices membrane bioreactor

Electronic are usually constructed from non-renewable, non-biodegradable, and hazardous materials. Due to the frequent upgrading or discarding of electronic devices, which contributes significantly to environmental pollution, there is a high demand for electronics made from renewable and biodegradable materials with less harmful components. To this end, due to their flexibility, strong mechanical, and optical properties, wood-based electronics have become very appealing as substrates especially for flexible electronics and optoelectronics. However, incorporating numerous features including high conductivity and transparency, flexibility, and mechanical robustness into an environmentally friendly electronic device remains very challenging. Herein, authors have provided the techniques used to fabricate sustainable wood based flexible electronics coupled with their chemical, mechanical, optical, thermal, thermomechanical, and surface properties for various applications. Additionally, the synthesis of a conductive ink based on lignin and the development of translucent wood as a substrate are covered. Future developments and broader applications of wood-based flexible materials are discussed in the final section of the study, with an emphasis on their potential in fields including wearable electronics, renewable energy, and biomedical devices. This research improves upon prior efforts by demonstrating new ways to simultaneously attain better mechanical and optical qualities and environmental sustainability.

A comprehensive review of lignocellulosic biomass derived materials for water/oil separation

With rapid socioeconomic development, oil is widely used in all aspects of modern society. However, the extraction, transport, and processing of oil inevitably lead to the production of large quantities of oily wastewater. Traditional oil/water separation strategies are often inefficient, costly, and cumbersome to operate. Therefore, new green, low-cost, and high-efficiency materials must be developed for oil/water separation. As widely sourced and renewable natural biocomposites, wood-based materials have become a hot field recently. This review will focus on the application of several wood-based materials in oil/water separation. The state of research on wood sponges, cotton fibers, cellulose aerogels, cellulose membranes, and some other wood-based materials for oil/water separation over the last few years and provide an outlook on their future development are summarized and investigated. It is expected to provide some direction for future research on the use of wood-based materials in oil/water separation.

Robust, Fire-Retardant, and Water-Resistant Wood/Polyimide Composite Aerogels with a Hierarchical Pore Structure for Thermal Insulation

The use of energy-saving materials is an effective strategy for decreasing energy consumption and carbon emission. Wood is a type of biomass material with a natural hierarchical structure, which results in its high thermal insulation. It has been widely used in construction. However, developing wood-based materials without flammability and dimensional instability is still a challenge. Herein, we developed a wood/polyimide composite aerogel with a well-preserved hierarchical pore structure and dense hydrogen bonds inside, resulting in its excellent chemical compatibility and strong interfacial interactions between its two components. This novel wood-based composite was fabricated by removing most hemicellulose and lignin from natural wood, followed by the fast impregnation using an 'in situ gel' process. The introduction of polyimide into delignified wood substantially improved its mechanical properties, with the compression resistance being improved by over five times. Notably, the thermal conductivity coefficient of the developed composite was approximately half that of natural wood. Furthermore, the composite exhibited excellent fire-retardancy, hydrophobicity, thermal insulation, and mechanical properties. This study provides a novel method for wood modification, which not only aids interfacial compatibility between wood and polyimide but also retains the properties of the two components. The developed composite can effectively reduce energy consumption, making it promising for practical and complex thermal insulation applications.

Inspired by Wood: Thick Electrodes for Supercapacitors

The emergence and development of thick electrodes provide an efficient way for the high-energy-density supercapacitor design. Wood is a kind of biomass material with porous hierarchical structure, which has the characteristics of a straight channel, uniform pore structure, good mechanical strength, and easy processing. The wood-inspired low-tortuosity and vertically aligned channel architecture are highly suitable for the construction of thick electrochemical supcapacitor electrodes with high energy densities. This review summarizes the design concepts and processing parameters of thick electrode supercapacitors inspired by natural woods, including wood-based pore structural design regulation, electric double layer capacitances (EDLCs)/pseudocapacitance construction, and electrical conductivity optimization. In addition, the optimization strategies for preparing thick electrodes with wood-like structures (e.g., 3D printing, freeze-drying, and aligned-low tortuosity channels) are also discussed in detail. Further, this review presents current challenges and future trends in the design of thick electrodes for supercapacitors with wood-inspired pore structures. As a guideline, the brilliant blueprint optimization will promote sustainable development of wood-inspired structure design for thick electrodes and broaden the application scopes.

Surfactant-Tunable Nanoparticle Assembly via a Template-Directed Strategy

Nanoparticle (NP) self-assembly from suspension evaporation has been a topic of interest in recent times to fabricate a solid-state structure with diverse functions. We present a simple and facile evaporation-induced strategy for the formation of NP arrays on a flat substrate utilizing a template-directed sandwich system. The lithographic features assist the assembly of the typical nanoparticles (NPs), including SiO₂, QDs@PS FMs, and QDs, on the top into circle, stripe, triangle, or square geometries with a fixed width of 2 μm. Additionally, an anionic surfactant, sodium dodecyl sulfonate (SDS), is incorporated into a negatively charged, hydrophilic SiO₂ dispersion to govern the aggregation and self-assembly of NPs, fine tuning the morphologies of the residual structures on the substrate. SDS is attributed to modify the nature of SiO₂ NPs to be hydrophobic, increase the hydrophobic attraction, dominating particle-particle and particle-interface interactions, and strengthen the particle-particle repulsive electrostatic force that results in the reduction of SiO₂ NPs trapped in the separated colloidal suspension drop. Thus, using the SDS surfactant with the concentration ranging from 0 to 1 wt %, the obtained well-ordered SiO₂ NP pattern packing on the substrate varies from six layers to one layer.

An Oxidative Enzyme Boosting Mechanical and Optical Performance of Densified Wood Films

Nature has evolved elegant ways to alter the wood cell wall structure through carbohydrate-active enzymes, offering environmentally friendly solutions to tailor the microstructure of wood for high-performance materials. In this work, the cell wall structure of delignified wood is modified under mild reaction conditions using an oxidative enzyme, lytic polysaccharide monooxygenase (LPMO). LPMO oxidation results in nanofibrillation of cellulose microfibril bundles inside the wood cell wall, allowing densification of delignified wood under ambient conditions and low pressure into transparent anisotropic films. The enzymatic nanofibrillation facilitates microfibril fusion and enhances the adhesion between the adjacent wood fiber cells during densification process, thereby significantly improving the mechanical performance of the films in both longitudinal and transverse directions. These results improve the understanding of LPMO-induced microstructural changes in wood and offer an environmentally friendly alternative for harsh chemical treatments and energy-intensive densification processes thus representing a significant advance in sustainable production of high-performance wood-derived materials.

Sustainable Thermal Energy Batteries from Fully Bio-Based Transparent Wood

The sustainable development of functional energy-saving building materials is important for reducing thermal energy consumption and promoting natural indoor lighting. Phase-change materials embedded in wood-based materials are candidates for thermal energy storage. However, the renewable resource content is usually insufficient, the energy storage and mechanical properties are poor, and the sustainability aspect is unexplored. Here a novel fully bio-based transparent wood (TW) biocomposite for thermal energy storage, combining excellent heat storage properties, tunable optical transmittance, and mechanical performance is introduced. A bio-based matrix based on a synthesized limonene acrylate monomer and renewable 1-dodecanol is impregnated and in situ polymerized within mesoporous wood substrates. The TW demonstrates high latent heat (89 J g^-1 ) exceeding commercial gypsum panels, combined with thermo-responsive optical transmittance (up to 86%) and mechanical strength up to 86 MPa. The life cycle assessment shows that the bio-based TW has a 39% lower environmental impact than transparent polycarbonate panels. The bio-based TW holds great potential as scalable and sustainable transparent heat storage solution.

Organized mineralized cellulose nanostructures for biomedical applications

Cellulose is the most abundant naturally-occurring polymer, and possesses a one-dimensional (1D) anisotropic crystalline nanostructure with outstanding mechanical robustness, biocompatibility, renewability and rich surface chemistry in the form of nanocellulose in nature. Such features make cellulose an ideal bio-template for directing the bio-inspired mineralization of inorganic components into hierarchical nanostructures that are promising in biomedical applications. In this review, we will summarize the chemistry and nanostructure characteristics of cellulose and discuss how these favorable characteristics regulate the bio-inspired mineralization process for manufacturing the desired nanostructured bio-composites. We will focus on uncovering the design and manipulation principles of local chemical compositions/constituents and structural arrangement, distribution, dimensions, nanoconfinement and alignment of bio-inspired mineralization over multiple length-scales. In the end, we will underline how these cellulose biomineralized composites benefit biomedical applications. It is expected that this deep understanding of design and fabrication principles will enable construction of outstanding structural and functional cellulose/inorganic composites for more challenging biomedical applications.

Sustainability in Wood Products: A New Perspective for Handling Natural Diversity

Wood is a renewable resource with excellent qualities and the potential to become a key element of a future bioeconomy. The increasing environmental awareness and drive to achieve sustainability is leading to a resurgence of research on wood materials. Nevertheless, the global climate changes and associated consequences will soon challenge the wood-value chains in several regions (e.g., central Europe). To cope with these challenges, it is necessary to rethink the current practice of wood sourcing and transformation. The goal of this review is to address the intrinsic natural diversity of wood, from its origin to its technological consequences for the present and future manufacturing of wood products. So far, industrial processes have been optimized to repress the variability of wood properties, enabling more efficient processing and production of reliable products. However, the need to preserve biodiversity and the impact of climate change on forests call for new wood processing techniques and green chemistry protocols for wood modification as enabling factors necessary for managing a more diverse wood provision in the future. This article discusses the past developments that have resulted in the current wood value chains and provides a perspective about how natural variability could be turned into an asset for making truly sustainable wood products. After briefly introducing the chemical and structural complexity of wood, the methods conventionally adopted for industrial homogenization and modification of wood are discussed in relation to their evolution toward increased sustainability. Finally, a perspective is given on technological potentials of machine learning techniques and of novel functional wood materials. Here the main message is that through a combination of sustainable forestry, adherence to green chemistry principles and adapted processes based on machine learning, the wood industry could not only overcome current challenges but also thrive in the near future despite the awaiting challenges.

Emerging Engineered Wood for Building Applications

The building sector, including building operations and materials, was responsible for the emission of ∼11.9 gigatons of global energy-related CO₂ in 2020, accounting for 37% of the total CO₂ emissions, the largest share among different sectors. Lowering the carbon footprint of buildings requires the development of carbon-storage materials as well as novel designs that could enable multifunctional components to achieve widespread applications. Wood is one of the most abundant biomaterials on Earth and has been used for construction historically. Recent research breakthroughs on advanced engineered wood products epitomize this material's tremendous yet largely untapped potential for addressing global sustainability challenges. In this review, we explore recent developments in chemically modified wood that will produce a new generation of engineered wood products for building applications. Traditionally, engineered wood products have primarily had a structural purpose, but this review broadens the classification to encompass more aspects of building performance. We begin by providing multiscale design principles of wood products from a computational point of view, followed by discussion of the chemical modifications and structural engineering methods used to modify wood in terms of its mechanical, thermal, optical, and energy-related performance. Additionally, we explore life cycle assessment and techno-economic analysis tools for guiding future research toward environmentally friendly and economically feasible directions for engineered wood products. Finally, this review highlights the current challenges and perspectives on future directions in this research field. By leveraging these new wood-based technologies and analysis tools for the fabrication of carbon-storage materials, it is possible to design sustainable and carbon-negative buildings, which could have a significant impact on mitigating climate change.

Robust flexural performance and fracture behavior of TiO2 decorated densified bamboo as sustainable structural materials

High-performance, fast-growing natural materials with sustainable and functional features currently arouse significant attention. Here, facile processing, involving delignification, in situ hydrothermal synthesis of TiO₂ and pressure densification, is employed to transform natural bamboo into a high-performance structural material. The resulting TiO₂-decorated densified bamboo exhibits high flexural strength and elastic stiffness, with both properties more than double that of natural bamboo. Real-time acoustic emission reveals the key role of the TiO₂ nanoparticles in enhancing the flexural properties. The introduction of nanoscale TiO₂ is found to markedly increase the degree of oxidation and the formation of hydrogen bonds in bamboo materials, leading to extensive interfacial failure between the microfibers, a micro-fibrillation process that results in substantial energy consumption and high fracture resistance. This work furthers the strategy of the synthetic reinforcement of fast-growing natural materials, which could lead to the expanded applications of sustainable materials for high-performance structural applications.

Research and Application of Biomass-Based Wood Flame Retardants: A Review

Wood is widely used as a construction material due to its many advantages, such as good mechanical properties, low production costs, and renewability. However, its flammability limits its use in construction. To solve the problem of wood flammability, the most common method to improve the fire safety of wood is to modify the wood by deep impregnation or surface coating with flame retardants. Therefore, many researchers have found that environmentally friendly and low-cost biomass materials can be used as a source of green flame retardants. Two aspects of biomass-based intumescent flame retardants are summarized in this paper. On the one hand, biomass is used as one of the three sources or as a flame-retardant synergist in combination with other flame retardants, which are called composite biomass intumescent flame retardants. On the other hand, biomass is used alone as a feedstock to produce all-biomass intumescent flame retardants. In addition, the potential of biomass-based materials as an environmentally friendly and low-cost FR source to produce high-performance biomass-based flame retardants with improved technology was also discussed in detail. The development of biomass-based intumescent flame retardants represents a viable and promising approach for the efficient and environmentally friendly production of biomass-based flame retardants.

Brushite mineralised Scots pine (Pinus sylvestris L.) sapwood - revealing mineral crystallization within a wood matrix by in situ XRD

Dicalcium phosphate dihydrate (CaHPO4·2H2O, DCPD, brushite) crystals were synthesised within Scots pine sapwood via a wet-chemistry route from aqueous solutions of Ca(CH3COO)2 and NH4H2PO4 salts. SEM/EDS analysis was used to assess the saturation of the wood cell lumina and cell wall as well as morphological features and elemental composition of the co-precipitated mineral. Brushite mineral crystallization and crystallite growth within the wood matrix was studied by in situ XRD. The chemical composition of the mineral before and after the dissolution was evaluated using FTIR spectroscopy. The overall impact of brushite on the thermal behaviour of wood was studied by TGA/DSC and TGA/DTA/MS analysis under oxidative and pyrolytic conditions. Bending and compression strength perpendicular and parallel to the fibre directions as well as bending strengths in longitudinal and transverse directions of the mineralised wood were also evaluated. Results indicate the viability of the wet-chemistry processing route for wood reinforcement with crystalline calcium phosphate (CaP)-based minerals, and imply a potential in producing hybrid bio-based materials that could be attractive in the construction sector as an environmentally friendly building material.

Multifunctional Flame-Retardant, Thermal Insulation, and Antimicrobial Wood-Based Composites

Wood has been used in a variety of applications in our daily lives and military industry. Nevertheless, its flammability causes potential fire risks and hazards. Improving the flame retardancy of wood is a challenging task. Herein, a phytic acid-based flame retardant (referred to as AMPA) was synthesized based on supramolecular reactions between melamine and p-amino-benzene sulfonic acid followed by a reaction with phytic acid using deionized water as the solvent. A composite wood was prepared by removing lignin to tailor the unique mesoporous structure of the material, followed by coating AMPA on the surfaces of wood microchannels. The limiting oxygen index of wood has been improved to 52.5% with the addition of 5.6 wt % AMPA. The peak heat release rate for the prepared composite wood was reduced by 81% compared to that for delignified wood, which demonstrates the excellent flame-retardant performance of the prepared composite wood. Furthermore, AMPA and mesoporous structures endow antimicrobial and thermal insulation functions. Hence, this work provides a feasible method for preparing flame-retardant wood-based materials for diversified applications.