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Transparent wood (TW) structures in research studies were either thin and highly anisotropic or thick and isotropic but weak. Here, transparent plywood (TPW) laminates are investigated as load-bearing biocomposites with tunable mechanical and optical performances. Structure-property relationships are analyzed. The plies of TPW were laminated with controlled fiber directions and predetermined stacking sequence in order to control the directional dependence of modulus and strength, which would give improved properties in the weakest direction. Also, the angular dependent light scattering intensities were investigated and showed more uniform distribution. Luminescent TPW was prepared by incorporation of quantum dots (QDs) for potential lighting applications. TPW can be designed for large-scale use where multiaxial load-bearing performance is combined with new optical functionalities. [ABSTRACT FROM AUTHOR]

Deformation mechanisms are largely unknown for superelastic carbon nanotube (CNT) aerogels, and this hampers materials design efforts. The CNT network in the cell walls is typically crosslinked or connected by a thermoset polymer phase. In order to create a recyclable superelastic aerogel, unmodified single or multi-walled CNTs were dispersed in water by adding to aqueous carboxymethyl cellulose (CMC) solution. Directional freeze-drying was used to form honeycombs with cell walls of random-in-the-plane CNTs in CMC matrix. Cell wall morphology and porosity were studied and related to CNT type and content, as well as elastic or plastic buckling of the cell walls under deformation. CMC acts as a physical crosslinker for the CNTs in a porous cell wall. Aerogel structure and properties were characterized before and after recycling. The conductivity of the composite aerogel with a density of 10 kg/m 3 , 99% porosity and 50 wt % single-walled CNT exceeds 0.5 S/cm. The potential of these superelastic and conductive aerogels for applications such as mechanoresponsive materials was examined in cyclic conductivity tests at different strains. This opens a new route for recyclable superelastic CNT composite aerogels, avoiding material loss, chemical treatment or addition of other components. [ABSTRACT FROM AUTHOR]

Fire retardant treatments that reduce the heat release rate of wood plastic composites (WPCs) have been intensively studied. However, few studies have reported on increasing the ignition time using precise control of nanostructured hybrids coating on WPC surfaces. Here, a nanocoating layer, composed of polyethyleneimine, Na-montmorillonite (MMT) and graphitized multiwalled carbon nanotubes, is deposited on the WPC surface via a layer-by-layer assembly (LbL). The nanocoating layer has favorable pull-off adhesion performance in dry and wet conditions. The protective layer has a "brick-mortar-rebar" nanostructure generating a thermal and gas barrier. This nanostructure prevents oxygen permeation and volatile gases release during material combustion. The thermal kinetics and decomposition reactions are restricted, increasing the ignition time from 49 s to 237–286 s, and 30% char formation due to the thermal shielding nature of MMT and the high charring capability of the coating nanostructure. The coating layer does not affect the WPC mechanical properties negatively. We foresee that this efficient multilayer hybrid coating method for improving fire-retardancy and smoke suppression could be applied to other materials, such as wood, foams, aerogels and polymer substrates. [Display omitted] • Layer-by-Layer nanostructured hybrids was coated on WPC. • The nanocoating produces excellent interfacial adhesion and protective barrier for WPC. • The nanostructure hybrids result in self-extinguishing and decrease of heat release rate. [ABSTRACT FROM AUTHOR]

Bamboo, a rapidly growing plant known for its remarkable strength-to-weight ratio and eco-friendly qualities, finds extensive applications in decorative construction materials and glue-laminated beams. However, the dimensional instability and flammability of natural bamboo limit its application range. In this study, a series of environmentally friendly methods are devised to produce functional bamboo hybrids possessing exceptional strength, excellent dimensional stability, and flame-retardant properties. These hybrids are created through bamboo delignification, in situ mineralization of CaCO3, and hot pressing after impregnation with phenolic resin. The highly aligned and densified nanocellulose stacking between hydrogen bonds of the bamboo hybrids results in the high tensile (583.6 MPa) and flexural strength (374.8 MPa), as well as an excellent specific strength of 486.3 MPa (cm3 g)−1. This value is significantly greater than those of other reported bamboo materials and most structural materials (e.g., steels and alloys). The favorable dimensional stability of the as-prepared bamboo hybrids is mainly associated with the impregnation of phenolic resin and mineralization of CaCO3 with the improvement of hydrophobicity. Compared to natural bamboo, the total heat release and smoke production rate of the bamboo hybrid were reduced by 37.7% and 50.0% respectively. This study provides a green processing strategy to manipulate and functionalize the microstructure of bamboo into high strength, superior fire-retardancy, and dimensional stability in various applications, such as structural construction, aerospace, and automotive manufacturing. [ABSTRACT FROM AUTHOR]

Metal-air batteries require the exploration of affordable electrocatalysts with exceptional catalytic performance for oxygen reduction reactions (ORR). One of the powerful ways to develop highly active and robust oxygen electrocatalysts is to load transition metal compounds onto a highly porous carbon aerogel. Here, we report a cell wall nanoengineering strategy to transform natural balsa wood into a wood-derived carbon aerogel (WCA), following by loading FeP nanoparticles inside the hierarchical N, P-doped WCA for ORR electrocatalysts. Wood nanotechnology is applied to manipulate the microstructure of the porous carbon aerogel with low-tortuosity, multichannel, and aligned pore, which benefits to the electron transportation for boosting the ORR. Under 0.1 M KOH conditions, the initial potential, half wave potential and limit current of FeP@N,P-WCA are 0.95 V, 0.84 V, and 5.20 mA cm−2 respectively, which are much higher than that of untreated wood and comparable to commercial Pt/C. The aqueous Zn-air batteries assembled with this catalyst exhibit a remarkable specific capacity of 775.5 mA h g−1 and better charge-discharge cycling stability. The excellent electrocatalytic activity demonstrated by FeP@N,P-WCA for ORR is attributed to the inherent tri-pathway (lumen, pit, and ray cell) porous structure of wood, the high conductivity and specific surface area of WCA (584.2 m2 g−1), and the highly dispersed FeP nanoparticles. This work provides a structural design concept for achieving high electrocatalytic biobased WCA reactors by combining wood nanotechnology and electrocatalysts chemistry for energy storage and conversion. A straightforward top-down synthesis method has been used to develop a three-dimensional porous wood carbon aerogel doped with non-noble metals, demonstrating excellent performance as an ORR electrocatalyst in zinc-air batteries. [Display omitted] • Utilizes hierarchical wood carbon aerogel, enhancing electron transport and ORR efficiency through tailored microstructure. • FeP@N,P-WCA achieves ORR performance comparable to commercial Pt/C. • Showcases a sustainable approach integrating wood nanotechnology with electrocatalyst chemistry, reducing reliance on precious metals. [ABSTRACT FROM AUTHOR]

With the development of emerging electronics and the increasing emphasis on environmental sustainability, there is a growing interest in flexible supercapacitors enhanced through the renewable solar energy. To address this demand, MXene materials with favorable electrical conductivity and photothermal performances have emerged as a promising option for the ideal electrodes. However, their widespread application has been hindered by issues such as severe self-stacking and limited irradiated area. Herein, a porous MXene flexible electrode capable of overcoming these challenges by incorporating softened wood (SW) is proposed for the first time. The selective removal of hemicellulose/lignin from wood renders SW flexible and exposes abundant oxygen-containing groups, forming a porous framework suitable for MXene loading. The polar attraction between these oxygen-containing groups and the MXene suspension facilitates rapid swelling of the SW. Through hydrogen bonding interactions, MXene nanosheets self-assemble on the SW, creating a continuous 3D conductive network. The 3D porous structure of SW enlarges both the contact area of active materials/electrolytes and the effective irradiated area of MXene/sunlight, improving electrochemical properties and photothermal performance. The flexible symmetric supercapacitor exhibits a significant areal capacitance (2225 mF cm−2), outstanding energy density (26.4 μWh cm−2) and notable solar-driven capacitance enhancement of 36 % within only 40 seconds under 1-solar illumination. This study introduces a novel design concept for eco-friendly flexible energy storage devices by integrating MXene with SW, demonstrating a promising pathway for developing sustainable and effective energy storage solutions. [Display omitted] • A porous MXene flexible electrode enhanced by softened wood is proposed. • Partial removal of hemicellulose/lignin enables wood soft and plenty MXene loading. • 3D structure enhances electrochemistry & photothermal performances of MSW. • The FSC delivers outstanding energy density and solar-enhanced capacitance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polycaprolactone and water-soluble chitosan were combined in 3D-printed drug delivery implant for sustained-release. • All the materials of the 3D-printed implant are biocompatible, biodegradable, low-toxic, cost-effective, renewable, and the method is simple and green. • The preparation process was carried out below 120 °C and solvent-free to maintain the drug activity. • Sustained release reached 99% and lasted for 120 h by tailoring the drug and chitosan content of the 3D-printed implant. Fused deposition molding (FDM) can complete most complex preparation of drug delivery implants to meet the personalized needs of patients. However, the drug activity has strict requirements on processing temperature and preparation method of filaments, the implant also has strict biocompatibility requirements for the materials. In this study, a drug delivery implant was prepared with good biocompatibility, controlled and efficient drug release using FDM printing for personalized administration. Drug-loaded filaments were developed for FDM process by hot-melt extrusion (HME). Polycaprolactone was used as a drug delivery carrier, and ibuprofen as the model drug. Notably, chitosan was dissolved to form controlled and efficient release channels. The printability, changes in physical and chemical properties during HME and FDM processes of the filament, and drug release behavior, mechanism and biocompatibility of the implants were investigated. The results showed that the filament tensile strength decreased with the increase of drug and chitosan content. No obvious degradation and chemical change occurred during the whole process. The drug release efficiency could reach>99% and lasted for 120 h mainly via the diffusion - erosion mechanism. The viability of cells cultured for 24 h in 72 h, 100% implant extract was 75.3%. [ABSTRACT FROM AUTHOR]

[Display omitted] • A nanostructured wood aerogel is developed for removal of Cu2+ from wastewater. • C 6 position of cellulose chains is oxidized into –COOH that can adsorb Cu2+. • Wood nanotechnologies enable to convert sustainable materials for removal of Cu2+. Heavy-metal pollution is a significant environmental issue that has raised global concern due to its harmful impact on humans and the natural ecosystem. Heavy metal pollution poses several challenges in terms of remediation, including low adsorption capacity and efficiency, scale-up issues and non-degradability. Here, we developed an eco-friendly tunable dual-wavelength absorption mesoporous wood aerogel (TDWA) for removal of Cu2+ ions from wastewater based on wood nanotechnology and carboxylated functionalization treatment. Nanostructured pores generated from the cell walls with carboxyl groups due to the removal of most lignin/hemicellulose and 2,2,6,6-tetramethylpiperidine oxidation. Mechanical compression was parallelly applied to the transverse direction of TDWA resulted in removing micron-scale cell cavity and intercellular, which significantly improved the dynamic adsorption performance with an excellent Cu2+ adsorption capacity of 115 mg g−1. This value is superior to most wood-based adsorption membrane as wastewater mainly flowed through the continuous microfibril network in the cell wall. The double-layer mesoporous TDWA membrane (5 mm) possessed a favorable removal efficiency (99.83 %) even after 5-cyclic adsorption (92.34 %). The invented nanostructured TDWA membrane in the current study has promising potential to substitute the present plastic-based membrane in the realistic Cu2+ adsorption because of the facile technology, renewability and high removal efficient, as well as the complete biodegradability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new strategy to fabricate hydrochromic transparent wood biocomposite with responsive-humidity function. • The appearance color of the hydrochromic transparent wood biocomposite is switchable under different humidity conditions. • The hydrochromic transparent wood biocomposite is demonstrated in application of humidity and fingerprint detection. Stimulus-responsive materials with smart detection of humidity and moisture have been attracting extensive attention in wooden products, including the potential of developing the next generations of intelligent transparent wood. In this work, a hydrochromic transparent wood (HTW) biocomposite with characteristics of responsive to humidity is developed by compounding the oxazoline molecules with the transparent wood. The uniform distribution of oxazoline molecules in the cell wall of the transparent wood biocomposite is observed via the X-ray micro-computed tomography. The relationships of process-structure–property of the HTW are extensively characterized through confocal fluorescence microscopy and scanning electron microscopy. The resulting HTW biocomposite also possesses favorable thermal stability and mechanical properties. Moreover, the hydrochromic transparent wood can realize stable switching colors under different humidity conditions due to the reversible opening or closing of the oxazine rings. The fingerprint detection and various shapes on the surface of HTW biocomposite are demonstrated in the wet condition. This study provides a promising strategy to combine the detection of environmental humidity function and wooden bioresource that could be extended to broaden applications in smart buildings, intelligent sensors, simulative detectors, and anti-counterfeiting identifications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Transparent wood-based functional materials via a top-down approach are critical. • The process–structure–property–application relationship of TWMs is provided. • Nanoscience and nanotechnologies can manipulate and functionalize wood materials. • Tunable properties based on structural design and chemical decoration are summarized. • The sustainable development and emerging applications of TWMs are highlighted. Transparent wood-based materials (TWMs), made by either bottom-up or top-down strategies, have attracted great attention owing to their transparency, sustainability and multifunctionality. Compared with materials prepared by a traditional bottom-up method, TWMs fabricated via a top-down approach are promising as the natural hierarchical structure of wood is preserved with a high production efficiency, energy savings and scalability. Wood nanotechnologies, various chemical treatments and polymer impregnation or densification techniques have been developed to fabricate TWMs, including transparent wood and transparent wood films, sharing similar sustainability and optical transmittance while also preserving some uniqueness in applications and compositions. Herein, we systematically provide an up-to-date summary on the state-of-the-art for transparent wood and transparent wood films, with a special highlight on the process–structure–property–application perspective, establishing the combination of wood science, material chemistry and physics with new horizons in TWM science. The integrated topics of TWMs emphasize the relationship between nanostructure and properties. The structural and functional design concepts are described for engineering production purposes. The emerging applications of TWMs are also discussed for the potential replacement of glass and petroleum-based plastics. Finally, an outlook and challenges are proposed for the future potential of functional TWMs in engineered production. [ABSTRACT FROM AUTHOR]

Enzymatic hydrolysis lignin (EHL) from ethanol production was used as an additive to incorporate in the wood flour/high-density polyethylene (HDPE) composite during the melt extrusion, and the incorporating effects on the mechanical and rheological properties of the resulting composites were investigated. The addition of EHL caused an improvement in both the tensile strength and impact strength, and a reduction in the complex viscosity of the composites as evidenced by the rotational rheometry, which suggests an increased flowability of the composite melt due to incorporation of EHL. The water absorption and swelling of the composites decreased with increasing EHL content during water immersion test. The scanning electron microscopy micrographs of EHL incorporated wood flour/high-density polyethylene composites showed a homogeneous dispersion of wood flour and EHL in the HDPE matrix. POLYM. COMPOS., 37:379-384, 2016. © 2014 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Transparent wood (TW) has been developed to combine the optical and functional aspects of wood. Many efforts have been dedicated to adding quantum dots, nanoparticles, or dyes to TW to provide additional functionalities, such as luminescent, electrochromic, thermochromic, and photo-switchable TW. However, the UV shielding performance and its new application of transparent wood are needed to explore. Herein, we report a photochromic transparent wood (PTW) by incorporating poly(methyl methacrylate) and UV/visible light switchable molecules into the delignified wood template. The focus is to investigate the relationship of process-structure-property of the PTW. The dispersion of photochromic molecules in PTW is shown by using energy-dispersive X-ray spectroscopy. The transmittance and the color of the PTW are switchable under UV and visible light excitation due to a change from the closed-ring to the open-ring form. Moreover, the PTW was found to possess, UV shielding performance, favorable thermal and mechanical properties, as well as excellent dimensional stability. We also demonstrate the potential smart packaging application of the UV-blocking PTW. We envision this PTW could be utilized for anti-counterfeit materials, intelligent sensors, and smart indicators. • The distribution of the photochromic molecules in transparent wood was investigated. • The fundamental understanding of the microstructure of photochromic transparent wood was provided. • The smart UV-shielding packaging material of photochromic transparent wood was demonstrated. [ABSTRACT FROM AUTHOR]