Solar-assisted fabrication of large-scale, patternable transparent wood

Regulating the Liquid-to-Solid Transition of a Solvent-Coordinated Metal Halide for Low-Temperature-Processed Pixelated Scintillators

Embedding large-refractive-index metal halides into small-refractive-index matrices to create pixelated scintillators with a waveguide structure holds great promise for next-generation X-ray detectors. However, the fabrication of these pixelated scintillators remains challenging. Herein, a solvent compensation and seed-assisted method is developed to enable reversible liquid-to-solid transitions of a solvent-coordinated metal halide (SMH) while preserving its scintillation properties under a vacuum. This allows the SMH to be liquefied with good flowability at 90 °C and facilitates its vacuum infiltration into organic matrices with vertically aligned pores. Consequently, low-temperature-processed pixelated scintillators are reported for the first time which show good flexibility and effective light confinement, achieving a spatial resolution approaching the theoretical limit.

An Ultrastrong and Ultraflexible Wood Veneer via Fiber Interaction Enhancement and Defect Reduction

Natural wood veneer is a flexible and sustainable material with significant potential for various applications. However, there are more defects in wood veneer, leading to lower strength, and the strengthening strategies currently used for wood blocks do not work well when applied to wood veneer. In this study, we processed the fragile wood veneer into an ultrastrong and ultraflexible material with a tensile strength of 578.4 MPa and preserved its beautiful wood texture. This enhancement is achieved by reducing defects within the veneer through adding cellulose molecules between the wood cell fibers. The resulting wood veneer is exceedingly flexible compared to natural wood, with a bending radius as small as 0.2 mm, while retaining its strength. This flexibility allows the veneer to be wrapped around other materials and improves the mechanical properties. The wood veneer exhibits much lower signal attenuation compared to carbon fiber fabric composites due to its electromagnetic transparency. Moreover, the environmental impact of producing each kilogram of this veneer is less than that of the carbon fiber material. These ultrastrong, ultraflexible, and sustainable properties of the wood veneer can enrich the family of lightweight, high-strength materials and enable a wide range of applications.

Hyperbranched Polyborophosphate towards Transparent Epoxy Resin with Ultrahigh Toughness and Fire Safety

Inherent transparency makes epoxy resins ideal for aircraft windows, yet their brittleness and flammability remain challenges. Existing strategies for these issues often compromise transparency, with limited research on the mechanisms involved. Herein, a novel strategy is proposed for fabricating transparent epoxy resin by tuning the electrostatic potential distribution via hyperbranched polyborophosphate. Electron-deficient boron and relatively electron-rich phosphorus atoms work synergistically to increase the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy gap, preventing visible light absorption. Meanwhile, the hyperbranched structure facilitates polymer network interpenetration to reduce porosity for decreased light scattering. This synergy results in a nearly colorless material with over 80% transmittance at 550 nm even at 4 mm thickness, along with full-band UV shielding. Notably, the material demonstrates a 114.7% increase in impact toughness (45.2 kJ m-2) due to dual dynamic B─O and P─O linkages. Besides, it yields a limiting oxygen index of 33% and a V0 rating in the underwriter laboratories vertical burning test, along with significant reductions in heat, smoke, and toxic gas release. The outstanding performance makes it stand out compared to reported advanced transparent epoxy resins, highlighting the significance of this work.

Sustainable transparent wood focusing on lignin decolorization methods, polymer impregnation techniques and applications in functional buildings: A review

The utilization of transparent wood as a potential composite derived from wood offers numerous advantages, including exceptional mechanical properties, lightweight, low thermal conductivity and immense potential for multifunctionality. Additionally, transparent wood demonstrates commendable performance in both thermal insulation and light transmission management, contributing to the reduction of energy consumption. This makes it an attractive option for buildings and related engineering elements. However, despite the successes achieved to date, further improvement is still required in terms of overall sustainability and functionality to meet the demands of advanced applications. This paper provides a comprehensive summary of the transparent wood preparation process, highlighting the efforts made to improve sustainability through various approaches. These strategies encompass using environmental-friendly chemicals or methods for lignin decolorization, substituting petroleum-based polymers with bio-based alternatives, and increasing the cellulose content through densification techniques. In addition, this paper presents the functionalization aspects of transparent wood such as chromism, heat shielding properties, ultraviolet shielding properties, luminescence, and fire-resistance, as well as its building applications. Finally, the challenges currently encountered in the development and application of transparent wood are discussed with an emphasis on the necessity for additional exploration and advancement in this area.

Transparent Wood Fabrication and Applications: A Review

Wood cellulose is an abundant bio-based resource with diverse applications in construction, cosmetics, packaging, and the pulp and paper industries. Transparent wood (TW) is a novel, high-quality wood material with several advantages over traditional transparent materials (e.g., glass and plastic). These benefits include renewability, UV shielding, lightweight properties, low thermal expansion, reduced glare, and improved mechanical strength. TW has significant potential for various applications, including transparent roofs, windows, home lighting structures, electronic devices, home decoration, solar cells, packaging, smart packaging materials, and other high-value-added products. The mechanical properties of TW, such as tensile strength and optical transmittance, are typically up to 500 MPa (Young's modulus of 50 GPa) and 10-90%, respectively. Fabrication methods, wood types, and processing conditions significantly influence the mechanical and optical properties of TW. In addition, recent research has highlighted the feasibility of TW and large-scale production, making it an emerging research topic for future exploration. This review attempted to provide recent and updated manufacturing methods of TW as well as current and future applications. In particular, the effects of structural modification through various chemical pretreatment methods and impregnation methods using various polymers on the properties of TW biocomposites were also reviewed.

Adhesive conductive wood-based hydrogel with high tensile strength as a flexible sensor

Conductive hydrogels have promising applications for flexible strain sensors. However, most hydrogels have poor tensile strength and are susceptible to damage, significantly impeding their potential for further application. Wood has been used to reinforce hydrogels, significantly enhancing their strength and dimensional stability. However, wood-based hydrogels generally lack adhesive properties or exhibit low self-adhesion. To address this issue, we introduced acryloyloxyethyltrimethyl ammonium chloride (DAC) into the hydrogel network through graft aggregation. The resulting electrostatic interactions significantly enhanced the adhesion of the wood-based hydrogel up to 270 kPa (for glass) and concurrently strengthened its cohesion. The prepared novel wood-based hydrogel (WDDH) exhibited high tensile strength (3.38 MPa), low-swelling ratio (only 2 % longitudinal), and high tensile strain (274.40 %). When WDDH was used as the wearable strain sensor, it showed a gauge factor of approximately 4.94. The device effectively captured and detected human movements, including finger and joint flexion, walking patterns, and hydration habits. The objective of this research is to develop a wood-based hydrogel with enhanced mechanical strength, adhesive properties, and flexibility for use in wearable sensors. This study provides insight into the development of flexible sensor hydrogels with improved adhesion properties using biomass materials.

Room-temperature phosphorescent transparent wood

Transparent wood with high transmittance and versatility has attracted great attention as an energy-saving building material. Many studies have focused on luminescent transparent wood, while the research on organic afterglow transparent wood is an interesting combination. Here, we use luminescent difluoroboron β-diketonate (BF2bdk) compounds, methyl methacrylate (MMA), delignified wood, and initiators to prepare room-temperature phosphorescent transparent wood by thermal initiation polymerization. The resultant PMMA has been found to interact with BF2bdk via dipole-dipole interactions and consequently enhance the intersystem crossing of BF2bdk excited states. The transparent wood matrix can provide a rigid environment for BF2bdk triplets and serve as oxygen barrier to suppress non-radiative decay and oxygen quenching. The prepared afterglow material has the characteristics of diverse composition, long afterglow emission lifetimes, and high photoluminescence quantum yield. This afterglow transparent wood also demonstrates potential application value in areas such as high mechanical strength, good hydrophobicity, and high cost-effectiveness.

A Comparison of the Optical Properties of Fibre-Based Luminescent Solar Concentrators and Transparent Wood Towards Sustainable Waveguides

Aiming at net-zero emissions, most international and national policies focus on sustainable development goals. Hence, there is an immediate need for replacing carbon-intensive materials with biomaterials. In this respect, this article presents a road-map for moving from polymeric to sustainable waveguides in optical devices. Previous reports indicate that luminescent fibres exhibit better photon concentrations of nearly 30%-33% higher than flat-plate polymeric waveguides. It is also verified that the photon in-out ratio increases by 3.44 times when the waveguide geometry is changed from planar to an equivalent area of fibre bundle with the same luminophore. Meanwhile, transparent wood (Twood) is gaining attention as a green alternative to acrylic sheets. The structure and function of transparent wood conforms well with the fibre-based waveguides of luminescent solar concentrators (LSCs). Therefore, it is intriguing to compare Twood with intrinsic micro fibrillary interior with fibre-based LSC as a natural alternative. This review provides an in-depth analysis, emphasizing the benefits and associated challenges in using cylindrical concentrators over planar LSCs. The paper collects and compares the phenomenon of light guiding of cylindrical and fibre-based LSCs with that of Twood. It is important to consider the key points discussed here while making a transition towards sustainable waveguides.

Ultraviolet (UV) assisted fabrication and characterization of lignin containing cellulose nanofibrils (LCNFs) from wood residues

This study aimed to explore the synergistic mechanism of lignin chromophore modifications via UV treatment and to analyze the effects of mechanical treatments on LCNF properties for future uses. The procedure involved two steps: first, lignin's chromophore modification via UV illumination, and then the ball milling process was proceeded for 1 h, followed by high-intensity ultrasonic for 15-135 min. Characterization included preserved lignin content percentage, FTIR, UV-vis NMR, and color analysis for UV-modified samples, and to access the influence of mechanical treatment on LCNF samples further yield, zeta potential analysis, XRD, thermogravimetric analysis, atomic force microscopy, and scanning electron microscopy were performed. LCNFs S-120 demonstrated a zeta potential of -21.7 mV, indicating enhanced stability compared to the S-135 sample (-10.95 mV). The S-120 sample also showed the highest yield (74.02 %) and TGA at 391 °C. In XRD analysis, the S-120 sample demonstrated the highest CrI 64.3 %, than the S-15 sample (48.2 %). Preserved lignin in the LCNFs led to a slight reduction in crystallinity across all samples but improved thermal stability for all the prepared LCNFs samples. The UV and ultrasonication improved the homogeneity and durability of the LCNF samples, enabling a process that may be used to industries.

Fabricating a high-loading smart film to monitor pork freshness via adsorption of anthocyanins on simultaneously etched, anionized and bleached wood cell wall

In this paper, wood cell walls were simultaneously roughened, carboxylated, and bleached via NaOH/H2O2 treatment and roughened-poplar film (RPF) was obtained. Compared with the untreated film, the carboxyl group content increased 8 times to 1.92 mmol/g, and the pore growth rate reached 11.24%. Afterwards, a pH-indicator wood film (CTA-RPF) was prepared by self-adsorption of anthocyanins on RPF. It rapidly changed from purple to green within 7 s in 0.25 mL of ammonia at 53% RH and the initial color could restore in the air. When anthocyanins adsorption capacity reached 1.95 mg/g, only 0.36 cm2 of the film could accurately indicate the quality change of 300 g pork. Currently, CTA-RPF is the smallest smart film that can track the maximum mass of pork after comparing with other researches, therefore, promising to be used as a smart indicator label to track the freshness of pork in real market circulation.

Enhancement of hybrid organohydrogels by interpenetrating crosslinking strategies for multi-source signal recognition over a wide temperature range

With substantial temperature differentials between summer and winter in polar regions, there exists a pressing necessity for flexible sensors capable of functioning across a broad temperature spectrum to facilitate the construction of a more intelligent human-machine interface. Nevertheless, developing flexible sensors resilient to extremely low temperatures remains a significant challenge. In this study, we present an organohydrogel capable of functioning ranging from ambient to -78 °C, enabling real-time monitoring of multi-source signals, including motion, physiology, speech, and pressure. We synthesize organohydrogel employing a singular methodology: interpenetrating network structures as matrix frameworks, dynamic hydrophobic linkages as the physical cross-linking points, and incorporating a bionic binder. H-Bonding and chain entanglement synergistic supramolecular interactions build the organohydrogel matrix with microphase-separated domains, which, together with the combination of binary solvents and inorganic salts, allows it to exhibit excellent properties, including large stretchability (≈1700%), high ionic conductivity (1.57 S m-1), admirable sensing sensitivity performance (gauge factor: GF = 6.47, S = 0.32 kPa-1), an exceptionally low-pressure detection threshold (≈1 Pa), enables wireless transmission of distress signals through human-machine interaction even at -78 °C, which makes it possible to use it in polar exploration and to give robots a "sense of touch" for a variety of deep-diving tasks.

Optically transparent and mechanically tough glass with impact resistance and flame retardancy enabled by covalent/supramolecular interactions

Exploring glass materials beyond inorganic components represents a new direction in the development of artificial transparent materials. Inspired by the successes of polymeric and supramolecular glasses, we shifted our attention to the preparation of a transparent glass through the polymerization of low-molecular-weight monomers that are naturally tailored with noncovalent recognition motifs. In this work, an imidazolium unit bearing a vinyl group and a tetrafluoroborate counter anion was selected to construct an artificial glass. Experimental and theoretical investigations revealed that the cross-linking behavior of anions effectively transformed linear polymeric chains into three-dimensional networks. The polymeric-supramolecular glass exhibits a tough tensile strength (61.31 MPa), high Young's modulus (1.17 GPa), and good optical transparency (>90%), which are comparable to those of polymethyl methacrylate. Moreover, the obtained glass maintains excellent mechanical toughness and optical transparency over a wide temperature range (from -150 to 150 °C). The material shows a superior impact resistance (18.34 kJ m-2) and flame retardancy (V0 rating), which are barely achieved by supramolecular materials.

Flexible, shape-editable wood-based functional materials with acetal linkages

A flexible, shape-editable transparent wood (ATW) composite containing acetal linkages was prepared simultaneously through free radical polymerization and addition reaction between vinyl ether bonds and hydroxyl groups. In this system, the anisotropic hierarchical structure of wood acted as a reinforced skeleton, the flexible chain segment ensured flexibility at room temperature, and the dynamic acetal bonds were responsible for the shape memory and editability under relatively mild conditions, verifying the expanding applications of functionalized wood-based materials.

Wood Cell Wall Nanoengineering toward Anisotropic, Strong, and Flexible Cellulosic Hydrogel Sensors

Achieving highly ionic conductive hydrogels from natural wood remains challenging owing to their insufficient surface area and low number of active sites on the cell wall. This study proposes a viable strategy to design a strong and anisotropic wood-based hydrogel through cell wall nanoengineering. By manipulating the microstructure of the wood cell wall, a flexible cellulosic hydrogel is achieved through Schiff base bonding via the polyacrylamide and cellulose molecular chains. This results in excellent flexibility and mechanical properties of the wood hydrogel with tensile strengths of 22.3 and 6.1 MPa in the longitudinal and transverse directions, respectively. Moreover, confining aqueous salt electrolytes within the porous structure gives anisotropic ionic conductivities (19.5 and 6.02 S/m in the longitudinal and transverse directions, respectively). The wood-based hydrogel sensor has a favorable sensitivity and a stable working performance at a low temperature of -25 °C in monitoring human motions, thereby demonstrating great potential applications in wearable sensor devices.

Large-Scale Engineerable Films Tailored with Cellulose Nanofibrils for Lighting Management and Thermal Insulation

Fibrillated cellulose-based nanocomposites can improve energy efficiency of building envelopes, especially windows, but efficiently engineering them with a flexible ability of lighting and thermal management remains highly challenging. Herein, a scalable interfacial engineering strategy is developed to fabricate haze-tunable thermal barrier films tailored with phosphorylated cellulose nanofibrils (PCNFs). Clear films with an extremely low haze of 1.6% (glass-scale) are obtained by heat-assisted surface void packing without hydrophobization of nanocellulose. PCNF gel cakes serve here as templates for surface roughening, thereby resulting in a high haze (73.8%), and the roughened films can block heat transfer by increasing solar reflection in addition to a reduced thermal conduction. Additionally, obtained films can tune distribution of light from visible to near-infrared spectral range, enabling uniform colored lighting and inhibiting localized heating. Furthermore, an integrated simulation of lighting and cooling energy consumption in the case of office buildings shows that the film can reduce the total energy use by 19.2-38.1% under reduced lighting levels. Such a scalable and versatile engineering strategy provides an opportunity to endow nanocellulose-reinforced materials with tunable optical and thermal functionalities, moving their practical applications in green buildings forward.

Transparent bamboo as a replacement for glass: Effects of lignin decolorisation methods on weatherability

Transparent bamboo proved to be a promising substitute for glass due to its high light transmittance and excellent mechanical properties. Nevertheless, it was susceptible to outdoor weathering, which negatively affected its physical and mechanical properties. In this study, two decolorisation methods, namely the delignification method and the lignin modification method, were used to produce transparent bamboos with epoxy resin, referred to as DL-TB and LM-TB, respectively. The changes in surface color, optical and mechanical properties, wettability, thermal stability, and thermal insulation properties of transparent bamboo during accelerated UV weathering were evaluated. Additionally, the deterioration mechanism of DL-TB and LM-TB was investigated. The findings revealed that DL-TB demonstrated better transparency and mechanical properties than LM-TB, although it exhibited lower thermal insulation properties. Furthermore, DL-TB demonstrated enhanced color stability and higher hydrophobicity on weathered surfaces than LM-TB. Unexpectedly, the tensile properties of both two transparent bamboos significantly improved after weathering, especially for LM-TB, which was due to the EP post-curing and the formation of more hydrogen bonds between lignin and EP. These observations revealed that lignin played a key role in the photodegradation process of transparent bamboo, but further attempts should be made in future studies to improve its color stability.

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.

Emerging approaches of utilizing trees to produce advanced structural and functional materials

The global number of trees is approximately 3 trillion, covering 31% of the land area. Trees are considered a cheap, abundant, renewable, and environmentally friendly feedstock for producing advanced structural and functional materials toward a widespread application in sustainable energy and environment. In this highlight, we reveal the structure and composition of wood, leaves, and tree extracts, and then highlight the strategies to control their hierarchical structures and properties. Moreover, we provide an up-to-date overview of their emerging applications in sustainable buildings, ionic nanofluidics, batteries, capacitors, solar cells, environmental remediation, biodegradable packaging, and nanomaterial synthesis. Finally, we outline the challenges and opportunities in valorizing trees for creating a sustainable future.

Powering the Future Green Buildings: Multifunctional Ultraviolet-Shielding Transparent Wood

Indoor UV damage is a serious problem that is often ignored. Common glasses cannot filter UV rays well and have fragility and environmental issues. UV-shielding transparent wood (TW) holds promise, yet striking the right balance between blocking UV rays and allowing sufficient visible-light transmission poses a challenge. The pronounced capillary force, fueled by persistent moisture and extractives in wood, alongside the existence of multiphase interfaces, collectively hinder the uniform penetration of polymers and the effective dispersion of nanomaterials within the wood skeleton. Here, we incorporate high-pressure supercritical CO2 fluid-assisted impregnation (HSCFI) into fabricating UV-shielding TW. The supercritical CO2 pretreatment efficiently eliminates moisture and refines wood structure by extracting polar substances, resulting in a prominent 52.4% increase in average water permeability. Subsequently, this HSCFI method facilitates the infiltration of methyl methacrylate (MMA) monomer and Ce-ZnO nanorods (NRDs) into the refined anhydrous wood, leveraging the excellent solvency of supercritical CO2 for MMA. The impregnation rate of PMMA undergoes a substantial increase from 34.5 to 59.1%. With the robust UV-blocking capability of Ce-ZnO NRDs, thanks to dual-valence Ce doping widening the ZnO energy gap via the Burstein-Moss effect and their unique photoactive microstructure featuring a solid prism with a sharp hexahedral pyramidal tip, along with intrinsic physical scattering/reflection actions, Ce-ZnO NRDs@TW achieves an impressive 99.6% UVA radiation blockage (the highest for TW) and maintains high visible-light transmission (83.2%). Furthermore, Ce-ZnO NRDs@TW presents favorable energy-saving, sound absorption, and antifungal abilities, making it a promising candidate for future green buildings.

Renewable biomass-based aerogels: from structural design to functional regulation

Global population growth and industrialization have exacerbated the nonrenewable energy crises and environmental issues, thereby stimulating an enormous demand for producing environmentally friendly materials. Typically, biomass-based aerogels (BAs), which are mainly composed of biomass materials, show great application prospects in various fields because of their exceptional properties such as biocompatibility, degradability, and renewability. To improve the performance of BAs to meet the usage requirements of different scenarios, a large number of innovative works in the past few decades have emphasized the importance of micro-structural design in regulating macroscopic functions. Inspired by the ubiquitous random or regularly arranged structures of materials in nature ranging from micro to meso and macro scales, constructing different microstructures often corresponds to completely different functions even with similar biomolecular compositions. This review focuses on the preparation process, design concepts, regulation methods, and the synergistic combination of chemical compositions and microstructures of BAs with different porous structures from the perspective of gel skeleton and pore structure. It not only comprehensively introduces the effect of various microstructures on the physical properties of BAs, but also analyzes their potential applications in the corresponding fields of thermal management, water treatment, atmospheric water harvesting, CO2 absorption, energy storage and conversion, electromagnetic interference (EMI) shielding, biological applications, etc. Finally, we provide our perspectives regarding the challenges and future opportunities of BAs. Overall, our goal is to provide researchers with a thorough understanding of the relationship between the microstructures and properties of BAs, supported by a comprehensive analysis of the available data.

Processing natural bamboo into white bamboo through photocatalyzed lignin oxidation

Scalable and highly efficient bamboo whitening remains a great challenge. Herein, an effective bamboo whitening strategy is proposed based on photocatalyzed oxidation, which involves H2O2 infiltration and UV illumination. The as-prepared white bamboo well maintains the nature structure of natural bamboo and demonstrates high whiteness and superior mechanical properties. The absorbance value is significantly decreased to 3.5 and the transmittance is increased to 0.04 % in UV-visible wavelength range due to the removal of light-absorbing chromospheres of lignin, resulting in a high whiteness when the UV illumination time is 8 h. In addition, the white bamboo displays a high tensile strength of 30 MPa and a high flexural strength of 36 MPa due to the well-preserved lignin units (lignin preservation is about 89 %). XRD patterns and analysis show that photocatalyzed oxidation has no effect on the crystal parameters of cellulose. Compared with the traditional bamboo whitening technology, our photocatalyzed oxidation strategy demonstrates significant advantage including chemical and time conservation, high efficiency, environment friendliness, and mechanical robustness. This highly efficient and environmentally friendly photocatalyzed oxidation strategy for the fabrication of white bamboo may pave the way of bamboo-based energy-efficient structural materials for engineering application.

Clearing techniques for deeper imaging of plants and plant-microbe interactions

Plant cells are uniquely characterized by exhibiting cell walls, pigments, and phenolic compounds, which can impede microscopic observations by absorbing and scattering light. The concept of clearing was first proposed in the late nineteenth century to address this issue, aiming to render plant specimens transparent using chloral hydrate. Clearing techniques involve chemical procedures that render biological specimens transparent, enabling deep imaging without physical sectioning. Drawing inspiration from clearing techniques for animal specimens, various protocols have been adapted for plant research. These procedures include (i) hydrophobic methods (e.g., Visikol™), (ii) hydrophilic methods (ScaleP and ClearSee), and (iii) hydrogel-based methods (PEA-CLARITY). Initially, clearing techniques for plants were mainly utilized for deep imaging of seeds and leaves of herbaceous plants such as Arabidopsis thaliana and rice. Utilizing cell wall-specific fluorescent dyes for plants and fungi, researchers have documented the post-penetration behavior of plant pathogenic fungi within hosts. State-of-the-art plant clearing techniques, coupled with microbe-specific labeling and high-throughput imaging methods, offer the potential to advance the in planta characterization of plant microbiomes.

Molecular-caged metal-organic frameworks for energy management

Metal-organic frameworks (MOFs) hold great promise for diverse applications when combined with polymers. However, a persistent challenge lies in the susceptibility of exposed MOF pores to molecule and polymer penetration, compromising the porosity and overall performance. Here, we design a molecular-caged MOF (MC-MOF) to achieve contracted window without sacrificing the MOF porosity by torsional conjugated ligands. These molecular cages effectively shield against the undesired molecule penetration during polymerization, thereby preserving the pristine porosity of MC-MOF and providing outstanding light and thermal management to the composites. The polymer containing 0.5 wt % MC-MOF achieves an 83% transmittance and an exceptional haze of 93% at 550 nanometers, coupled with remarkable thermal insulation. These MC-MOF/polymer composites offer the potential for more uniform daylighting and reduced energy consumption in sustainable buildings when compared to traditional glass materials. This work delivers a general method to uphold MOF porosity in polymers through molecular cage design, advancing MOF-polymer applications in energy and sustainability.

Synthesis of lignin-based resin and fabrication of sustainable transparent wood based on bio-recycling concept

Transparent wood (TW) has attracted much attention in the field of energy saving building structural materials because of its high light transmittance, good thermal insulation performance and good toughness. However, the polymeric resins used in the present study to impregnate lignin-based wood templates are usually derived from petroleum-based chemical resources, which pose a fatal threat to human beings both in terms of consuming large amounts of resources and causing environmental pollution problems. It is therefore important to develop alternatives to petroleum-derived chemicals in renewable natural resources. Here, we report a green and sustainable TW production process based on the bio-recycling concept. Lignin-based sustainable resin (LSR) was prepared from waste lignin produced during delignification by polymerization of guaiacol. At the same time, according to FT-IR and NMR data analysis combined with previous studies, the synthesis mechanism of LSR was proposed, and this result provided a reference for bio-based resins made from biomass materials. The prepared lignin-based sustainable transparent wood (LSTW) has good light transmittance and good dimensional stability. In addition, the LSTW also shows good thermal insulation and indoor temperature regulation capabilities compared with the common glass.

Mismatched Refractive Index Strategy for Fabricating Laser-Driven Wood Diffusers from Bulk Wood for Illumination Applications

Laser-diode-based solid-state lighting is primarily used in state-of-the-art illumination systems. However, these systems rely on light-converting inorganic phosphors, which have low quantum efficiencies and complex manufacturing conditions. In this study, a mismatched refractive index strategy is proposed to directly convert natural bulk wood into a laser-driven wood diffuser using a simple delignification and polymer infiltration method. The resulting material has the potential to be used in laser-driven diffuse illumination applications. The optical performance of the laser-driven wood diffuser is optimized by changing the density of natural wood. The optimal coefficient of illuminance variation of the wood diffuser is as low as 17.7%, which is significantly lower than that of commercial diffusers. The illuminance uniformity is larger than 0.9, which is significantly higher than the ISO requirements for indoor workplace lighting. The laser damage threshold is 7.9 J cm-2, which is considerably higher than those of the substrates of commercially available phosphors. Furthermore, the optimized wood diffuser exhibits outstanding mechanical properties, excellent thermal stability, tolerance to harsh environmental conditions, and low speckle contrast. These results show that the laser-driven wood diffuser is a promising laser-color converter that is suitable for indoor, long-distance outdoor, undersea, and other high-luminance laser lighting applications.

Construction and mechanism analysis of flame-retardant, energy-storage and transparent bio-based composites based on natural cellulose template

With the proposal of sustainable development strategy, bio-based energy storage transparent wood (TW) has shown broad application value in green buildings, cold chain transportation, and optoelectronic device fields. However, its application in most fields is limited due to its own flammability. In this study, epoxy resin, triethyl phosphate (TEP) and polyethylene glycol (PEG) were introduced into delignified balsa wood template by vacuum pressure impregnation, and bio-based TW/PEG/TEP integrating flame retardant, high strength and phase-change energy-storage performance was prepared. TW/PEG composites have no leakage during phase change process and their transparency is up to 95 %. Compared with TW/PEG, the shielding effect of char layer and the inhibition effect in condensed and gas phase significantly decrease the total heat release of TW/PEG/TEP. TW/PEG/TEP biocomposites still maintained a high enthalpy of phase change and a low peak melting temperature, which was conducive to its application around the area of low temperature phase change energy storage. In addition, the tensile strength of TW/PEG/TEP was nearly 4 times higher than that of DW, and its toughness was obviously enhanced. TW/PEG/TEP biocomposites conformed to the current concept of energy-saving and green development. It has the potential to replace traditional petrochemical-based materials and shows excellent application prospects in emerging fields.

A Microphase-Separated Design toward an All-Round Ionic Hydrogel with Discriminable and Anti-Disturbance Multisensory Functions

Stretchable ionic hydrogels with superior all-round properties that can detect multimodal sensations with excellent discriminability and robustness against external disturbances are highly required for artificial electronic skinapplications. However, some critical material parameters exhibit intrinsic tradeoffs with each other for most ionic hydrogels. Here, a microphase-separated hydrogel is demonstrated by combining three strategies: (1) using of a low crosslinker/monomer ratio to obtain highly entangled polymer chains as the first network; (2) the introduction of zwitterions into the first network; (3) the synthesis of an ultrasoft polyelectrolyte as the second network. This all-round elastic ionic hydrogel exhibits a low Young's modulus (< 60 kPa), large stretchability (> 900%), high resilience (> 95%), unique strain-stiffening behavior, excellent fatigue tolerance, high ionic conductivity (> 2.0 S m⁻1), and anti-freezing capability, which have not been achieved before. These properties allow the ionic hydrogel to operate as a stretchable multimodal sensor that can detect and decouple multiple stimuli (temperature, pressure, and proximity) with excellent discriminability, high sensitivity, and strong sensing-robustness against strains or temperature perturbations. The ionic hydrogel sensor exhibits great potential for intelligent electronic skin applications such as reliable health monitoring and accurate object identification.

Programmable and Shape-Color Synchronous Dual-Response Wood with Thermal Stimulus

Stimuli-responsive materials exhibit huge potential in sensors, actuators, and electronics; however, their further development for reinforcement, visualization, and biomass-incorporation remains challenging. Herein, based on the impregnation of thermochromic microcapsule (TCM)-doped dynamic covalent vitrimers, a programmable shape-color dual-responsive wood (SRW-TC) was demonstrated with robust anisotropic structures and exchangeable covalent adaptable networks. Under mild conditions, the resultant SRW-TC displays feasible shape memorability and programmability, resulting from the rigidity-flexibility shift induced by the glass-transition temperature (34.99 °C) and transesterification reaction triggered by the topology freezing transition temperature (149.62 °C). Furthermore, the obtained SRW-TC possesses satisfactory mechanical performance (tensile strength of 45.70 MPa), thermal insulation (thermal conductivity of 0.27 W/m K), anisotropic light management, and benign optical properties (transmittance of 51.73% and haze of 99.67% at 800 nm). Importantly, the incorporation of compatible TCM enables SRW-TC to visualize shape memory feasibility and rigidity/flexibility switching and respond to the external thermal stimulus through the thermal-induced shape-color synchronous dual-responsiveness, which successfully demonstrates the applications of sensing temperature, grasping objects, encrypting/decoding icon messages, and so on. The proposed facile and highly effective strategy could serve as a guideline for developing high-performance multifunctional wood composite with promising intelligent applications in performance visualization, environmental sensing, materials interactivity, information dual-encryption, local precision shape and color regulation, etc.

Mechanically strong, hydrostable, and biodegradable all-biobased transparent wood films with UV-blocking performance

Petroleum-based plastics are useful but they pose a great threat to the environment and human health. It is highly desirable yet challenging to develop sustainable structural materials with excellent mechanical and optical properties for plastic replacement. Here, we report a simple and efficient method to manufacture high-performance all-biobased structural materials from cellulosic wood skeleton (WS) and gelatin via oxidation and densification. Specifically, gelatin was grafted to the oxidized cellulose wood skeletons (DAWS) and then physically crosslinked via Tannic acid (TA), resulting in a significant enhancement of the material properties. Notably, only a mild pressure was applied during the drying process to form a densified TA/Gelatin/transparent wood film(TWF). The developed TA/Gelatin/TWF (thickness:100 ± 12 μm) exhibited a desirable combination of high strength (∼154.59 MPa), light transmittance (86.2 % at 600 nm), low haze (16.7 %), high water stability (wet strength: ∼130.13 MPa) and ultraviolet blocking efficacy which surpass most of the petroleum-based plastics. In addition, due to the all bio-based origins (wood and gelatin), TA/Gelatin/TWF are easily biodegradable under natural conditions, leading to less impact on the environment. These findings would hold promises for exploring high-quality all bio-based wood composites as eco-friendly alternatives to substitute plastics with wide applications, e.g. anti-counterfeiting, UV protection, and flexible electricals.

Farming on the Ocean via Desalination (FOOD)

Today, agricultural irrigation consumes the largest amount of freshwater globally, while humans are threatened by water scarcity. To eliminate the trade-off between hunger and thirst, here, we show off-grid maritime agriculture based on a floating solar-driven agro-desalination wooden dome. In this dome, part of the visible light is transmitted for photosynthesis, and the remaining solar energy drives solar desalination, providing enough water (>4 mm day-1) for irrigation. Based on this water-food synergy, the stages of germination and growth are demonstrated. This technology can, to a large extent, support food security and sustainable agriculture and, in principle, be used to create self-circulation systems at sea to help humans survive weather extremes such as floods and droughts.

Mycelium Composite with Hierarchical Porous Structure for Thermal Management

High-performance porous materials with a low carbon footprint provide sustainable alternatives to petroleum-based lightweight foams and can help meet carbon neutrality goals. However, these materials generally face a trade-off between thermal management capabilities and structural strength. Here, a mycelium composite with a hierarchical porous structure, including both macro- and microscale pores, produced from multiple and advanced mycelial networks (elastic modulus of 1.2 GPa) binding loosely distributed sawdust is demonstrated. The morphological, biological, and physicochemical properties of the filamentous mycelium and composites are discussed in terms of how they are influenced by the mycelial system of the fungi and the way they interact with the substrate. The composite shows a porosity of 0.94, a noise reduction coefficient of 0.55 at a frequency range of 250-3000 Hz (for a 15 mm thick sample), a thermal conductivity of 0.042 W m-1  K-1 , and an energy absorption of 18 kJ m-3 at 50% strain. It is also hydrophobic, repairable, and recyclable. It is expected that the hierarchical porous structural composite with excellent thermal and mechanical properties can make a significant impact on the future development of highly sustainable alternatives to lightweight plastic foams.

Perovskite-Coated Thermochromic Transparent Wood: A Novel Material for Smart Windows in Energy-Efficient and Sustainable Buildings

Transparent wood (TW) has emerged as a sustainable alternative to conventional glass as an energy-efficient window glazing material owing to its exceptional optical transparency and superior mechanical and thermal performances. However, it is challenging to develop the TW-based color-switching smart windows with both high optical performance and mechanical strengths. In this work, an optically switchable and mechanically robust perovskite-coated thermochromic transparent wood (PTTW) is developed for use as smart windows to achieve an effective solar modulation and thermal management. PTTW exhibits a substantial solar modulation ability Δτsol of 21.6% and a high clear-state luminous transmittance τlum of 78.0%, which enable an efficient thermal regulation while ensuring high visual clarity. PTTW also offers enhanced mechanical properties (i.e., tensile strength σtens = 71.4 MPa and flexural strength σflex = 93.1 MPa) and improved thermal properties [i.e., thermal conductivity K = 0.247 W/(m·K) and heat capacity C = 1.69 J/(g·°C)] compared to glass-based smart windows, as well as excellent performance stability (i.e., 200 heating-cooling cycles), manifesting its applicability in real building scenarios. In addition, PTTW also demonstrates a remarkable thermal-regulating performance (i.e., 5.44 °C indoor air temperature regulation) and an energy-saving potential (i.e., 12.9% heating, ventilation, and air conditioning energy savings) in Hong Kong. Overall, this study contributes to the progression toward energy-efficient and sustainable buildings.

Lignocellulose-Based Optical Biofilter with High Near-Infrared Transmittance via Lignin Capturing-Fusing Approach

Near-infrared (NIR) transparent optical filters show great promise in night vision and receiving windows. However, NIR optical filters are generally prepared by laborious, environmentally unfriendly processes that involve metal oxides or petroleum-based polymers. We propose a lignin capturing-fusing approach to manufacturing optical biofilters based on molecular collaboration between lignin and cellulose from waste agricultural biomass. In this process, lignin is captured via self-assembly in a cellulose network; then, the lignin is fused to fill gaps and hold the cellulose fibers tightly. The resulting optical biofilter featured a dense structure and smooth surface with NIR transmittance of ~90%, ultralow haze of close to 0%, strong ultraviolet-visible light blocking (~100% at 400 nm and 57.58% to 98.59% at 550 nm). Further, the optical biofilter has comprehensive stability, including water stability, solvent stability, thermal stability, and environmental stability. Because of its unique properties, the optical biofilter demonstrates potential applications in the NIR region, such as an NIR-transmitting window, NIR night vision, and privacy protection. These applications represent a promising route to produce NIR transparent optical filters starting from lignocellulose biomass waste.

Transparent wood composite prepared from two commercially important tropical timber species

Transparent wood (TW) has garnered significant global attention due to its unique properties. In this study, TW composites were fabricated using two timber species of different density classes: Ailanthus triphysa (common name: Ailanthus wood) and Hevea brasiliensis (common name: Rubberwood). Sodium hydroxide (NaOH) and Hydrogen peroxide-based alkali method was used to modify the lignin in these veneer samples, producing a white cellulose template with a fully intact hierarchical cell structure. Subsequently, a cost-effective thermosetting unsaturated polyester resin (UPR) was infiltrated into the redesigned framework and polymerized to create rigid nanostructured transparent composites. High optical haze (of 94% and 89%) and favourable light transmittance of 59 and 55 percent were exhibited by the UPR-TW composites made from rubberwood and ailanthus wood, respectively. TW was characterised using Scanning electron microscopy and Fourier-transform infrared spectroscopy. The mechanical properties of TW were measured and compared with those of natural wood and pure-polymer. Furthermore, the anisotropic light diffusion behaviour displayed by TW in accordance with the fibre orientation indicates the utility of material as a potential light shaping device. Therefore, a cost-effective and commercially viable strategy to fabricate multipurpose TW composites using a combination of lesser-known timber species (LKTS) and UPR resin was successfully demonstrated.

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.

Insight into the Charge-Ratio-Tuned Solar Vapor Generation of Polyion Complex Hydrogel/Coal Powder Composites

Solar-driven water purification has been deemed a promising technology to address the issue of clean water scarcity. However, traditional solar distillers often suffer from low evaporation rates under natural sunlight irradiation, while the high costs of the fabrication of photothermal materials further hinders their practical applications. Here, through the harnessing of the complexation process of oppositely charged polyelectrolyte solutions, a polyion complex hydrogel/coal powder composite (HCC)-based highly efficient solar distiller is reported. In particular, the influence of the charge ratio of polyanion-to-polycation on the solar vapor generation performance of HCC has been systematically investigated. Together with a scanning electron microscope (SEM) and the Raman spectrum method, it is found that a deviation from the charge balance point not only alters the microporous structure of HCC and weakens its water transporting capabilities, but also leads to a decreased content of activated water molecules and enlarges the energy barrier of water evaporation. As a result, HCC prepared at the charge balance point exhibits the highest evaporation rate of 3.12 kg m^-2 h^-1 under one sun irradiation, with a solar-vapor conversion efficiency as high as 88.83%. HCC also exhibits remarkable solar vapor generation (SVG) performance for the purification of various water bodies. In simulated seawater (3.5 wt% NaCl solutions), the evaporation rate can be as high as 3.22 kg m^-2 h^-1. In acid and alkaline solutions, HCCs are capable of maintaining high evaporation rates of 2.98 and 2.85 kg m^-2 h^-1, respectively. It is anticipated that this study may provide insights for the design of low-cost next-generation solar evaporators, and broaden the practical applications of SVG for seawater desalination and industrial wastewater purification.

Wood xerogel for fabrication of high-performance transparent wood

Optically transparent wood has been fabricated by structure-retaining delignification of wood and subsequent infiltration of thermo- or photocurable polymer resins but still limited by the intrinsic low mesopore volume of the delignified wood. Here we report a facile approach to fabricate strong transparent wood composites using the wood xerogel which allows solvent-free infiltration of resin monomers into the wood cell wall under ambient conditions. The wood xerogel with high specific surface area (260 m² g^-1) and high mesopore volume (0.37 cm³ g^-1) is prepared by evaporative drying of delignified wood comprising fibrillated cell walls at ambient pressure. The mesoporous wood xerogel is compressible in the transverse direction and provides precise control of the microstructure, wood volume fraction, and mechanical properties for the transparent wood composites without compromising the optical transmittance. Transparent wood composites of large size and high wood volume fraction (50%) are successfully prepared, demonstrating potential scalability of the method.

Room temperature phosphorescence from natural wood activated by external chloride anion treatment

Producing afterglow room temperature phosphorescence (RTP) from natural sources is an attractive approach to sustainable RTP materials. However, converting natural resources to RTP materials often requires toxic reagents or complex processing. Here we report that natural wood may be converted into a viable RTP material by treating with magnesium chloride. Specifically, immersing natural wood into an aqueous MgCl₂ solution at room temperature produces so-called C-wood containing chloride anions that act to promote spin orbit coupling (SOC) and increase the RTP lifetime. Produced in this manner, C-wood exhibits an intense RTP emission with a lifetime of ~ 297 ms (vs. the ca. 17.5 ms seen for natural wood). As a demonstration of potential utility, an afterglow wood sculpture is prepared in situ by simply spraying the original sculpture with a MgCl₂ solution. C-wood was also mixed with polypropylene (PP) to generate printable afterglow fibers suitable for the fabrication of luminescent plastics via 3D printing. We anticipate that the present study will facilitate the development of sustainable RTP materials.

N-Doped Carbon Fibers Derived from Porous Wood Fibers Encapsulated in a Zeolitic Imidazolate Framework as an Electrode Material for Supercapacitors

Developing highly porous and conductive carbon electrodes is crucial for high-performance electrochemical double-layer capacitors. We provide a method for preparing supercapacitor electrode materials using zeolitic imidazolate framework-8 (ZIF-8)-coated wood fibers. The material has high nitrogen (N)-doping content and a specific surface area of 593.52 m² g^-1. When used as a supercapacitor electrode, the composite exhibits a high specific capacitance of 270.74 F g^-1, with an excellent capacitance retention rate of 98.4% after 10,000 cycles. The symmetrical supercapacitors (SSCs) with two carbon fiber electrodes (CWFZ2) showed a high power density of 2272.73 W kg^-1 (at an energy density of 2.46 W h kg^-1) and an energy density of 4.15 Wh kg^-1 (at a power density of 113.64 W kg^-1). Moreover, the SSCs maintained 81.21% of the initial capacitance after 10,000 cycles at a current density of 10 A g^-1, which proves that the SSCs have good cycle stability. The excellent capacitance performance is primarily attributed to the high conductivity and N source provided by the zeolite imidazole framework. Because of this carbon material's unique structural features and N-doping, our obtained CWFZ2 electrode material could be a candidate for high-performance supercapacitor electrode materials.

A comprehensive review of the synthesis strategies, properties, and applications of transparent wood as a renewable and sustainable resource

The uncertainties of the environment and the emission levels of nonrenewable resources have compelled humanity to develop sustainable energy savers and sustainable materials. One of the most abundant and versatile bio-based structural materials is wood. Wood has several promising advantages, including high toughness, low thermal conductivity, low density, high Young's modulus, biodegradability, and non-toxicity. Furthermore, while wood has many ecological and structural advantages, it does not meet optical transparency requirements. Transparent wood is ideal for use in various industries, including electronics, packaging, automotive, and construction, due to its high transparency, haze, and environmental friendliness. As a necessary consequence, current research on developing fine wood is summarized in this review. This review begins with an explanation of the history of fine wood. The concept and various synthesis strategies, such as delignification, refractive index measurement methods, and transparent lumber polymerization, are discussed. Approaches and techniques for the characterization of transparent wood are outlined, including microscopic, Fourier transform infrared (FTIR), and X-ray diffraction (XRD) analysis. Furthermore, the characterization, physical properties, mechanical properties, optical properties, and thermal conductivity of transparent wood are emphasized. Eventually, a brief overview of the various applications of fine wood is presented. The present review summarized the first necessary actions toward future transparent wood applications.

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.

Hofmeister Effect-Enhanced Hydration Chemistry of Hydrogel for High-Efficiency Solar-Driven Interfacial Desalination

Solar-driven water evaporation technology holds great potential for mitigating the global water scarcity due to its high energy conversion efficiency. Lowering the vaporization enthalpy of water is key to boost the performance of solar-driven desalination. Herein, a highly hydratable hydrogel (PMH) network, consisting of modified needle coke as photothermal material and polyvinyl alcohol (PVA) as hydratable matrix, is crafted via simple physical cross-linking method. When capitalizing on the PMH as evaporator for 3.5 wt% NaCl solution, a high evaporation rate of 3.18 kg m^-2  h^-1  under one sun illumination is deliver ed, unexpectedly outperforming that in pure water (2.53 kg m^-2  h^-1 ). More importantly, the PMH shows a robust desalination durability, thus enabling a self-cleaning system. Further investigations reveal that the outstanding evaporation performance of PMH in brine roots in its hydrability tuned by chaotropic Cl^- , wherein the Cl^- can mediate the hydration chemistry of PVA in PMH and suppress related crystallinity, thus contributing to the increased content of intermediate water and the lowered vaporization enthalpy of brine. This work first scrutinizes the Hofmeister effect on the evaporation behavior of PMH evaporator in brine and provides insights for high-efficiency solar-driven interfacial desalination.

Potential new material for optical fiber: Preparation and characterization of transparent fiber based on natural cellulosic fiber and epoxy

In order to reduce the dependence on fossil energy products, natural fiber/polymer hybrid composites have been increasingly researched. The high price of the quartz optical fibers and glass optical fibers has greatly inspired researchers to engage in the research on polymer optical fibers. Herein, transparent fibers based on plant fibers were innovatively prepared for the first time by delignification and impregnating epoxy diluted with acetone. The epoxy improved the thermal stability of the fiber without deteriorating its mechanical properties, and also endowed the fiber with the property of transparency. The tensile strength of transparent fibers of three diameters were 34.5, 58.6 and 100.3 MPa, respectively and the corresponding Young's modulus reached 1.1, 1.7 and 2.3 GPa, respectively. In addition, the light-conducting properties of transparent fibers were displayed with a green laser and the fibers displayed good light transmission along the fiber growth direction. Transparent fibers are expected to be used in optical fibers because of their high thermal stability, good mechanical properties and light-conducting properties.

Environment-friendly AgNWs/Ti3C2Tx transparent conductive film based on natural fish gelatin for degradable electronics

Recently, the electronic waste (E-waste) has become the most serious environmental trouble because of the iteration of electronic products. Transparent conductive films (TCFs) are the key component of flexible electronic devices, so the development of devices based on degradable TCFs has become an important way to alleviate the problem of E-waste. Gelatin, one of the most prevalent natural biomacromolecules, has drawn increasing attention due to its good film-forming ability, superior biocompatibility, excellent degradability, and commercial availability at a relatively low cost, but has few applications in flexible electronics. Here, we report a method for preparing flexible TCF based on naturally degradable material-fish gelatin, in which silver nanowires and Ti3C2Tx flakes were used as conductive fillers. The obtained TCF has low roughness (RMS roughness = 5.62 nm), good photoelectric properties (Rs = 25.2 Ω/sq., T = ca.85% at 550 nm), strong interfacial adhesion and good degradability. Moreover, the film showed excellent application in the field of EMI shielding and green light OLED device. We believe that these TCFs will shine in the smart wearable field in the future.

Facile and green synthesis of nanocellulose with the assistance of ultraviolet light irradiation for high-performance quasi-solid-state zinc-ion batteries

Benefiting from excellent mechanical properties, large surface area, rich hydroxyl groups, good sustainability, etc., nanocellulose is highly promising for various applications. However, intense chemical treatment and long-term processing are usually required to fabricate nanocellulose. Herein, a new synthesis method of nanocellulose is developed by using ultraviolet light irradiation-assisted delignification and subsequent sonification. This method is more cost-effective, time-saving, and environmentally benign compared to most of previously reported synthesis methods of nanocellulose. The obtained nanocellulose contains a small amount of lignin, which is unfavorable for high-temperature stability and optimal transparency. However, a small amount of lignin is beneficial to mechanical properties and in-water stability. With this nanocellulose, flexible MnO₂ cathode film and hydrogel electrolyte are constructed and a quasi-solid-state zinc-ion battery is assembled. The battery exhibits 233.3 mAh g^-1 after 1000 cycles at 1 A g^-1 and 20 ℃. And more than half of that capacity can be maintained at -20 ℃. The battery also possesses great rate capability and good endurance to external forces. This work provides new insights into the synthesis and application of nanocellulose.

Ultraviolet-Assisted Modified Delignified Wood with High Transparency

The substrate of solar cells with high haze, transparent, flexible, green and low coatings will be needed in the future. This paper reports a method for ultraviolet-assisted delignification of wood in an alkaline solution environment to improve the transmittance of “transparent wood”. Scanning electron microscope (SEM), X-ray diffraction image (XRD), Fourier transform infrared (FTIR) spectroscopy and transmittance-haze and chemical composition analysis were used to explore the mechanisms underlying the effect of ultraviolet-assisted lignin modification on the optical properties of “transparent wood”. The results show that UV-assisted delignification accelerates the rate of removal of lignin and chromogenic groups, which in turn improves the optical properties of the “transparent wood”, with UV-assisted lignin modification for 2 h increasing the light transmission of the “transparent wood” by 20%. UV-assisted delignification for 4 h and impregnation resulted in “transparent wood” with a transparency of 71% and a haze of 90%. This report provides a rapid and easy method to prepare high-quality “transparent wood”. The “transparent wood” with high transmittance and high haze is a potential candidate for transparent solar substrates. Meanwhile, this method is enlightening for high quality, fast and green preparation of other derived functional materials based on lignin wood.

Effect of Bleaching and Hot-Pressing Conditions on Mechanical Properties of Compressed Wood

This paper reports on multiple stage bleaching and its effect on the mechanical and swelling properties of compressed wood (CW). The natural wood specimen was bleached with NaClO₂ in five steps and three hot-pressing conditions. Their effects were investigated in morphologies: lignin content, alpha-cellulose content, compression ratio, mechanical properties, swelling and, water contact angle. After compression, the wood specimens became dense and the most porous structures collapsed. The lignin content decreased as the bleaching steps progressed, and the highest alpha-cellulose content was observed at the third bleaching step. This CW showed the best mechanical properties: bending strength was 240.1 ± 35.7 MPa, and Young’s modulus was 23.08 ± 0.89 Gpa. The CW swelling decreased as the bleaching step progressed, and was associated with the density decrease and the compression ratio increase with the bleaching step. The B3 is an optimum bleaching step that accounts for the best mechanical properties, which might be associated with the highest alpha-cellulose content.

Interpretation of Strengthening Mechanism of Densified Wood from Supramolecular Structures

In this study, densified wood was prepared by hot pressing after partial lignin and hemicellulose were removed through alkaline solution cooking. The tensile strength and elastic modulus of densified wood were improved up to 398.5 MPa and 22.5 GPa as compared with the original wood, and the characterization of its supramolecular structures showed that the crystal plane spacing of the densified wood decreased, the crystallite size increased, and the maximum crystallinity (CI) of cellulose increased by 15.05%; outstandingly, the content of O(6)H⋯O(3′) intermolecular H-bonds increased by approximately one-fold at most. It was found that the intermolecular H-bond content was significantly positively correlated with the tensile strength and elastic modulus, and accordingly, their Pearson correlation coefficients were 0.952 (p < 0.01) and 0.822 (p < 0.05), respectively. This work provides a supramolecular explanation for the enhancement of tensile strength of densified wood.

Highly efficient and selective modification of lignin towards optically designable and multifunctional lignocellulose nanopaper for green light-management applications

Transparent lignocellulose nanopaper (LNP) has been demonstrated to be a promising candidate light-management material for next-generation optical engineering applications. Similar to its role in plant cell walls, lignin serves as a vital functional component in LNP matrices. However, its intrinsic light absorption property renders LNP undesirable for a range of optical management systems. Here, a highly efficient, controllable and ecofriendly lignin modification strategy is developed for modulating the optical performance of LNPs by taking advantage of the beneficial synergistic effect of H₂O₂ and UV light in selectively eliminating lignin chromophores. The obtained lignin-modified LNP features not only a high visible light transmittance (89%) but also a high haze (90%) and excellent UV-shielding capacity, owing to the well-preserved lignin aromatic skeleton structures after lignin modification. Furthermore, patterning is easily achieved on hot-pressing-induced densified LNPs through a selective lignin modification approach, which endows LNPs with intriguing optical designability. Benefitting from the multifunctionality of lignin components for nanopaper matrices, patterned LNPs demonstrate outstanding water and thermal stability, barrier properties, durability and biodegradability, which are of great significance for practical applications. Furthermore, we demonstrate the great applicability of this optically designable and multifunctional LNP as a light-management material for energy efficient buildings by highlighting its attractive sun- and indoor- light managing effects, effective thermal insulation, as well as superior durability for long-term use. In combination with its efficient, ecofriendly and controllable production, this novel high-performing LNP holds great potential in many other applications that require light-management structural materials, such as optoelectronic and sensing devices.