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Nanocellulose films have been extensively studied for their excellent oxygen barrier properties. However, in the presence of moisture and higher humidity, the oxygen barrier performance decreases rapidly. In this work, natural rubber latex (NRL) was used as a compounding material to improve the hydrophobic properties of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) oxidized nanocellulose fibers (TOCNF) due to the ability of its naturally occurring phospholipid-protein surface to avoid the interfacial compatibility problems that exist in most hydrophobic polymers when mixed in aqueous solutions. The exposure of the internal hydrophobic isoprene molecular chains of NRL during the drying process allows the composite film to have greatly improved water resistance and excellent water vapor and oxygen barrier properties. The water vapor permeability (WVP) and oxygen permeability (OP) of the films were as low as 6.07×10− 10g·mm/m2·s·pa and 3.11×10− 15 cm3·cm/cm2·s·Pa, respectively. And the good water resistance of the composite film makes the wet tensile strength of the film up to 15.87 MPa, which reaches 71.69% of the dry tensile strength. In addition, the high ductility of NRL makes the laminate film good toughness, and its elongation at break can reach about three times that of most nanocellulose-based films. Experiments on strawberry preservation with composite films have shown that it can effectively slow down the deterioration of strawberries and extend their shelf life from two days to seven days. This study highlights the exceptional promise of these innovative films for use in food packaging applications.

Thehighly efficient utilization of lignin is of great importance for the development of the biorefinery industry. Herein, a novel "core-shell" lignin nanoparticle (LNP) with a diameter of around 135 nm was prepared, after the lignin was isolated from the effluent of formic acid fractionation via dialysis. In an attempt to endow composite materials with vital functionalities, the LNP was added to the starch film and the starch/polyvinyl alcohol (PVA) or starch/polyethylene oxide (PEO) composite film. The results showed that the hydrophobicity performance of the synthesized films was enhanced significantly. Specifically, the dynamic water contact angle value of the starch/PVA composite film with 1% (wt) addition of LNPs could be maintained as high as 122° for 180 s; the starch/PEO composite film also achieved an excellent water contact angle above 120°. The addition of LNPs promoted the formation of some rough structures on the film surface, as shown by the scanning electron microscopy images, which could repel the water molecules efficiently and are closely related to the enhanced hydrophobicity of the starch film. What is more, the as-prepared LNP conferred strengthened thermal stability and ultraviolet blocking properties on the starch composite film. The structural combination of the polymer film with LNPs holds the promise for providing advanced functionalities to the composite material with wide applications.

A novel, non-porous carbon structure was obtained through pyrolysis of biomass heterostructures consisting of cellulose and lignin.The novel class of biomass-derived carbon materials exhibit an enhanced electromagnetic (EM) loss capability due to the nano-antenna structure created by in-situ growth of carbon nanofibers on carbon nanosheets.The designed carbon materials exhibit good hydrophobicity and acid/base resistance, suggesting a stable EM absorption performance in diverse environmental conditions, thus making it a good candidate for real world conditions. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00750-z., Although advances in wireless technologies such as miniature and wearable electronics have improved the quality of our lives, the ubiquitous use of electronics comes at the expense of increased exposure to electromagnetic (EM) radiation. Up to date, extensive efforts have been made to develop high-performance EM absorbers based on synthetic materials. However, the design of an EM absorber with both exceptional EM dissipation ability and good environmental adaptability remains a substantial challenge. Here, we report the design of a class of carbon heterostructures via hierarchical assembly of graphitized lignocellulose derived from bamboo. Specifically, the assemblies of nanofibers and nanosheets behave as a nanometer-sized antenna, which results in an enhancement of the conductive loss. In addition, we show that the composition of cellulose and lignin in the precursor significantly influences the shape of the assembly and the formation of covalent bonds, which affect the dielectric response-ability and the surface hydrophobicity (the apparent contact angle of water can reach 135°). Finally, we demonstrate that the obtained carbon heterostructure maintains its wideband EM absorption with an effective absorption frequency ranging from 12.5 to 16.7 GHz under conditions that simulate the real-world environment, including exposure to rainwater with slightly acidic/alkaline pH values. Overall, the advances reported in this work provide new design principles for the synthesis of high-performance EM absorbers that can find practical applications in real-world environments. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00750-z.

The exploration of functional films using sustainable cellulose-based materials to replace plastics has been of much interest. In this work, two kinds of lignin nanoparticles (LNPs) were mixed with cellulose nanofibrils (CNFs) for the fabrication of composite films with biodegradable, flexible and ultraviolet blocking performances. LNPs isolated from p-toluenesulfonic acid hydrolysis was easily recondensed and deposited on the surface of composite film, resulting in a more uneven surface; however, the composite film consisting of CNFs and LNPs isolated from maleic acid hydrolysis exhibited a homogeneous surface. Compared to pure CNF film, the composite CNF/LNP films exhibited higher physical properties (tensile strength of 164 MPa and Young’s modulus of 8.0 GPa), a higher maximal weight loss temperature of 310 °C, and a perfect UVB blocking performance of 95.2%. Meanwhile, the composite film had a lower environmental impact as it could be rapidly biodegraded in soil and manmade seawater. Overall, our results open new avenues for the utilization of lignin nanoparticles in biopolymer composites to produce functional and biodegradable film as a promising alternative to petrochemical plastics.

Due to the current state of ozone layer depletion and potential risk of skin cancer, researches on sustainable cellulose-based films with ultraviolet (UV) blocking capabilities has attracted widespread attention. However, pure cellulose-based film required UV absorbent to be incorporated because of its poor UV blocking ability. In this work, natural lignocellulosic nanofibril (LCNF) film was fabricated by vacuum filtration and pressing process without any complex chemical modification or adding UV absorbers. The residual lignin retained in LCNF was found to act as natural macro-molecular UV absorber. LCNF film with lignin content of 4.89–15.68% exhibited excellent thermal stability, and their UVA and UVB blocking were in the range of 81.4–99.5% and 96.7–100%, respectively. Moreover, LCNF film exhibited stable UV shielding performance under high temperature, UV irradiation, acidic or alkaline conditions, providing LCNF film with a long-term use capacity. Overall, LCNF film is more environmentally friendly and harmless, which shows high potentials in anti-counterfeiting materials, UV protection, and windshields for vehicles.

Preparing cellulose II nanocrystals (CNC II) requires a polymorph transformation of natural cellulose I feedstocks. The transformation is usually achieved via a process such as mercerization or dissolution–regeneration. This study demonstrated a new method to prepare CNC II directly from bleached kraft pulp (BKP, a commercially available cellulose I feedstock) in a mildly acidic lithium bromide trihydrate (MALBTH) system, a concentrated (∼61 wt%) solution of LiBr in water with a very low concentration (2.5 mM) of sulfuric acid. First, the BKP was treated in the MALBTH system to generate a cellulose II hydrolysis solid residue (CHR) with a yield of 64–86%, during which the selective hydrolysis of disordered cellulose and the polymorph transformation were completed simultaneously. Then, subsequent oxidation of the CHR by ammonium persulfate (APS, 0.1–0.6 M) resulted in the CNC II with high yield (up to 62%), high crystallinity (over 90%), rich surface carboxyl group (0.3–1.2 mmol g−1 cellulose), excellent colloidal stability (up to −59 mV zeta potential), and high thermal stability. The CNC II had a tunable length (26–57 nm), determined by the conditions of the MALBTH hydrolysis and the APS oxidation, but similar lateral dimension (8–10 nm). The characterization of the CHR by wide-angle X-ray diffraction and Fourier transform infrared spectroscopy verified the polymorphic transformation from cellulose I to II during the MALBTH treatment. The swelling of the BKP in the MALBTH enabled cellulose crystallites to slide and reassemble, which completed the rearrangement of cellulose chains from parallel to anti-parallel conformation (polymorph transformation from cellulose I to II). This study provided an efficient and green method to produce cellulose II nanocrystals with controllable aspect ratios via the simultaneous hydrolysis and polymorph transformation of cellulose I feedstocks.

Cellulose is lack of UV-blocking and antibacterial properties, which have limited its application. In this work, the nanoscale lignin with high content of hydroxyl groups and small particle size in prehydrolysate was isolated and used as a green reinforcement ingredient for fabrication of cellulose nanofibril (CNF) films with excellent mechanical properties, as well as UV protection and antibacterial capabilities. Cryogenic transmission electron microscopy (Cryo-TEM) and nuclear magnetic resonance analyses showed that the resulting lignin was in the form of nanoparticles (6–12 nm) with high phenolic hydroxyl contents (4.9 mmol/g). The optimum lignin inclusion rate of 5% allowed it to reinforce CNF composite film, increasing its tensile strength from 108.5 to 143.3 MPa. In addition, the film exhibited excellent UV protection capabilities. It blocked 91.5% of UV-A and 99.9% of UV-B light. Finally, the resulting lignin-based CNF films exhibited antibacterial activities against both Escherichia coli and Streptococcus hemolyticus. This work demonstrates the utility of nanoscale lignin from prehydrolysate can be used to produce cellulose-based composite films with valuable properties.

Lignocellulosic nanofibrils (LCNF) has caused great interest from researchers due to the benefits of high output, low operation cost, and weak environmental impact. The existence of lignin in LCNF ...

In this work, a versatile cellulose nanocrystal‑carbon dots (CNC-CDs) architecture is prepared and applied in environmental remediation and biological sensing. The citric acid (CA) is employed to extract CNCs and in-situ synthesize blue-emissive CDs. The carboxyl-rich surface of CNC-CDs enables the chelation of Hg

Developing renewable and biodegradable materials derived from cellulose is an attractive strategy to replace petroleum-derived plastics. In this study, metal ions (Cu

Cellulose-based aerogels are considered to be carriers that can absorb oils and organic solvents owing to the merits of low density and high surface area. However, the natural hydrophility and poor mechanical strength often obstruct their widespread applications. In this work, Miscanthus-based dual cross-linked lignocellulosic nanofibril (LCNF) aerogels were prepared by gas phase coagulation and methylene diphenyl dissocyanate (MDI) modification. Due to physical and chemical cross-linking strategies, the optimally 4 M-LCNF aerogels had high surface area of 157.9 m

Lignin, a renewable and low-cost biopolymer, has been widely reported as an energy-storage material. The energy-storage capability of lignin primarily originates from the redox of its internal quinone group. Hence, effective optimization of the lignin structure is of great significance for increasing the quinone group content, which is vital for improving the energy-storage performance of lignin-based electrode materials. Herein, synthetic polymers (SPs) with an extremely high quinone group content were prepared using lignin-derived aromatic monomers (LDAMs) as precursors. The chemical structure of the SP samples was analyzed using 13C and 31P NMR, and the results showed that their quinone content was as high as 5.49–6.75 mmol g−1, which is 6–7 times higher than that of commercial kraft lignin (KL). The RGO/SP composite was prepared using ultrasound-assisted self-assembly, and as expected, the SP coupled with reduced graphene oxide acquired a high specific capacitance of 352–465 F g−1, which is 1.4–1.9 times higher than that of RGO/KL. In addition, the RGO/SP electrodes showed an excellent rate performance of 265–365 F g−1 at 10 A g−1. Overall, our strategy provides a possibility for the preparation of high-performance lignin-based energy-storage materials.

Cellulose nanofibrils (CNFs) have attracted great attention because of their unique mechanical and optical properties for a variety of applications in composites, packaging materials, and electroni...

Each year millions of tons of agricultural wastes are produced, however, not well utilized in China. Considering the economic development and environmental protection, the valorization of these wastes is increasingly necessary and important. Here we used p-toluenesulfonic acid hydrolysis followed by mild disk grinding for on-farm valorization of wheat straw (WS) and their pulping solid residue (waste wheat straw, WWS) to produce lignocellulosic nanofibrils (LCNF). Alkaline peroxide post-treatment was further conducted to obtain purified lignocellulosic nanofibrils (P-LCNF) with lower lignin content and thinner diameters. The raw materials and resulting LCNF and P-LCNF were investigated in each process for their chemical component, crystal structure, morphology, and thermal properties. Interestingly, although WS fiber had higher lignin content than WWS fiber, the WS fiber with lower ash content resulted in LCNF and P-LCNF with smaller height and lower thermal stability, but higher crystallinity and higher specific surface area. Higher ash content in WWS fiber protected cellulose and lignin from depolymerization and degradation, respectively, which endowed LCNF and P-LCNF with entangled network structure. Overall, this study indicated that the low-temperature fractionation process on WS and WWS fibers could yield cellulose nanomaterials with potential value-added application and achieve the efficient utilization of agricultural wastes.

The cellulose-rich residual solids are obtained with p-toluenesulfonic acid (p-TsOH) treatment. However, better fractionation of hemicellulose and separation is difficult to obtain during treatment. This study aims at investigating the separation selectivity of bamboo hemicellulose using freeze-thaw-assisted p-TsOH (F/p-TsOH) treatment. The desired separation effect was achieved at freezing temperature -40 °C, freezing time 20 h, p-TsOH concentration 3.0 %, treatment temperature 130 °C and time 80 min. 93.26 % hemicellulose separation was found, which was 32.88 % higher than that of conventional p-TsOH treatment. Furthermore, the separation yield of lignin decreased significantly from 69.29 % to 13.98 %. The distinct lignin characteristic absorption peaks were found, while that of hemicellulose was difficult to observe. The fiber crystallinity index increased from 50.42 to 56.55 %. Furthermore, greater selectivity for hemicellulose separation was achieved. The results provide a new research thinking for efficient fractionation of lignocellulosic biomass by organic acid treatment.

When old corrugated cardboard (OCC) is returned to the paper mill for repulping and reuse, the starch, which is added to the paper surface as a reinforcement agent, is dissolved into the pulping wastewater. Most of the OCC pulping wastewater is recycled to save precious water resources; however, during the water recycling process, the accumulation of dissolved starch stimulates microbial reproduction, which causes poor water quality and putrid odor. This problem seriously affects the stability of the papermaking process and product quality. In this study, phosphomolybdic acid (H

Rice straw hydrotropic lignin was extracted from p-Toluene sulfonic acid (p-TsOH) fractionation with a different combined delignification factor (CDF). Hydrotropic lignin characterization was systematically investigated, and alkaline lignin was also studied for the contrast. Results showed that the hydrotropic rice straw lignin particle was in nanometer scopes. Compared with alkaline lignin, the hydrotropic lignin had greater molecular weight. NMR analysis showed that β-aryl ether linkage was well preserved at low severities, and the unsaturation in the side chain of hydrotropic lignin was high. H units and G units were preferentially degraded and subsequently condensed at high severity. High severity also resulted in the cleavage of part β-aryl ether linkage. 31P-NMR showed the decrease in aliphatic hydroxyl groups and the increasing carboxyl group content at high severity. The maximum weight loss temperature of the hydrotropic lignin was in the range of 330–350 °C, higher than the alkaline lignin, and the glass conversion temperature (Tg) of the hydrotropic lignin was in the range of 107–125 °C, lower than that of the alkaline lignin. The hydrotropic lignin has high β-aryl ether linkage content, high activity, nanoscale particle size, and low Tg, which is beneficial for its further valorization.

The naturally tight entanglement of fibers in bacterial cellulose (BC) results in low printability when BC is used as a bioink for printing scaffolds. In this study, neat BC was treated by TEMPO-mediated oxidation (TO-BC) and maleic acid (MA-BC) to prepare homogeneous BC dispersions to fabricate scaffolds for bone regeneration. Results showed that the treatments released individual fibrils in the corresponding uniform dispersions without impairing inherent crystalline properties. Compared with TO-BC, MA-BC hybridized with gelatin could endow the gel with improved rheological properties and compression modulus for 3D printing. Both TO-BC and MA-BC dispersions showed good osteoblast viability. However, MA-BC possessed more pronounced ability to express osteogenic marker genes and formation of mineralized nodules in vitro. Compared with TO-BC-based gelatin scaffolds, MA-BC-based gelatin scaffolds showed a better ability to stimulate the regeneration of rat calvaria, demonstrating a higher bone mineral density of newly formed bone and trabecular thickness in vivo.

When old corrugated cardboard (OCC) is returned to the paper mill for repulping and reuse, the starch, which is added to the paper surface as a reinforcement agent, is dissolved into the pulping process water. Most of the OCC pulping wastewater is recycled to save precious water resources; however, during the water recycling process, the accumulation of dissolved starch stimulates microbial reproduction, which causes poor water quality and putrid odor. This problem seriously affects the stability of the papermaking process and product quality. In this study, phosphomolybdic acid (H3PMo12O40, abbreviated as PMo12) was utilized to oxidatively degrade the waste starch present in papermaking wastewater to monosaccharides, realizing the resource utilization of waste starch. The results showed that the optimized yield of total reducing sugar (73.54 wt%) and glycolic acid (11.05 wt%)was achieved at 145 °C with 30 wt% PMo12, which is equivalent to 84.59 wt% starch recovered from wastewater. In addition, the regeneration of the reduced PMo12 was realized applying a potential of 1 V for 2 h. Overall, this study has theoretical significance and potential application value for resource utilization of waste starch in OCC pulping process and cleaner management of OCC waste paper.

The premise of high value utilization of lignocellulosic biomass is effective separation of hemicellulose. In this paper, the extraction of bamboo hemicellulose using freeze-thaw assisted alkali treatment (FAT) was studied. The effect of alkali concentration, alkali treatment time, freezing temperature, and freeze-thaw time on the main components was studied. Bamboo was frozen at −30 °C for 12 h, thawed at room temperature, and then treated at 75 °C for 90 min with 7.0% alkali. The extraction rate of hemicellulose was as high as 64.71%. The purity of hemicellulose samples using conventional AT decreased from 82.63% to 78.56%. Hemicellulose with the same yield as that of conventional alkali treatment was obtained by further reducing the alkali concentration. The purity of hemicellulose samples increased from 82.63% to 89.45%. It had a higher purity, higher molecular weight, and lower polydispersity. A new, green and efficient alkaline extraction method for hemicellulose was developed.

A novel recyclable deep eutectic solvent (DES) consisting of p-toluene sulfonic acid (p-TsOH) and choline chloride (ChCl) was developed for efficient woody poplar sawdust (PL) and herbaceous miscanthus (MC) conversion at mild condition. The extraction of leftover lignin on the surface of DES pretreated residues using NaOH solution at room temperature greatly improved the enzymatic hydrolysis efficiency. Near complete cellulose conversion of PL and MC residues were obtained with a degree of delignification and xylan removal over 90% at 100 °C within 40 min. The strong correlations between xylan (R2 = 0.95) and lignin (R2 = 0.82) removal with cellulose conversion were observed in MC as well as positive correlations (R2 > 0.77) in PL. The results demonstrated that the DES system coupling NaOH post-treatment was a promising method to achieve an economically feasible biomass conversion process, which was effective for both woody PL residues and herbaceous MC.

Renewable lignocellulosic biomass can be effectively transformed to value-added products, enabling fast growth of related downstream processing. However, valorization of the by-produced cellulose-poor fraction, which is also in large volumes, is only occasionally reported regarding existing technologies. Here, a simple, general, and effective strategy for fabricating graphene quantum dots (GQDs) from the Miscanthus (MC) biorefinery waste consisting of sugars and depolymerized lignin, is developed. This process involves the fast and selective removal of most lignin and hemicellulose based on mild acid hydrotrope fractionation, with followed hydrothermal carbonization. The as-fabricated MC-derived GQDs (M-GQDs) exhibit several advantages such as few-layer graphene-like single crystalline structure, sulfur and nitrogen co-doping, bright fluorescence, excitation-dependent photoluminescence, and long fluorescence lifetime (11.95 ns). Furthermore, M-GQDs present prominent fluorescence reduction in the presence of Fe

We conducted the first comparative exploration on lignin containing cellulose nanofibril films prepared alternatively from willow bark and wood using a highly recyclable acid hydrotrope, aqueous p-toluenesulfonic acid, as a sustainable means for isolating the nanofibrils. The nanofibrils of willow bark were hydrophobic and produced dense films of high strength under hot pressing. The hydrophobicity resulted from condensation of the residual lignin with low molecular weight aromatic substances of the bark and hydroxymethylfurfural formed in situ from fructose that is also present in the bark.

The usage of thermally conductive materials is limited due to their low thermal conductivity, poor thermal stability and brittleness, particularly at high working temperatures. In this work, for the first time, lignin nanoparticles (LNPs) were utilized to enhance the thermal conductivity, stability, flame-retardancy, and flexibility of boron nitride (BN)-OH/polyvinyl alcohol (PVA) composite film, which played an important role as reinforcements. BN-OH/PVA/LNP composite film was fabricated through vacuum filtration in conjunction with chemical cross-linking. With the loading of LNPs at 2.5 vol%, the BN-OH/PVA/LNP composite film exhibited a higher through-plane thermal conductivity (up to 1.74 W m−1 K−1) than the one without LNPs (1.65 W m−1 K−1). After cross-linking with glutaraldehyde (GA), the elongation of the composite at break was 132%, an increase of 267% compared with the non-crosslinked one. The initial decomposition temperature of the BN-OH/PVA composite film was approximately 260 °C. However, in the presence of 7.1 vol% LNPs, the BN-OH/PVA/LNP composite film started to degrade at a much higher temperature, i.e., 310 °C, demonstrating improved thermal stability. Furthermore, the addition of LNPs enhanced the flame-retardancy of the composites according to the burn test and differential scanning calorimetry (DSC). The resulting composite film with multiple improved properties is highly promising as a thermal interface material (TIM) and packaging material for various applications.

Generally, the mechanical strength and stiffness of old corrugated cardboard (OCC) waste paper are decreased after multiple recycling procedures. Surface sizing starch, which is extensively used in the surface sizing of paper making, accumulates after dissolving from the fibers and is transformed into pollutant during the OCC re-pulping process. To overcome the pollution and reutilization problem of the waste starch during the recycling process of OCC paper, waste starch was ionized using hydrogen peroxide (H2O2) to improve the mechanical properties of OCC paper during the reutilization. The results showed that the carboxyl group of waste starch increased with an increasing degree of ionization, resulting in enhanced copper ion adsorption capacity. Furthermore, the retention rate of the modified starch in the wet-end increased from 18.0% to 48.2%. The OCC paper presented the highest burst index and tensile strength of 8.94 kPa m2/g and 112.5 N m/g, respectively, when MS-2 was added. This work has great significance for implementation of the cleaning production of OCC waste papers and the reutilization of the waste starch.

To avoid complex and toxic chemical cross-linking reaction, cellulose nanofibrils (CNF) was used to enhance the performance of hexagonal boron nitride nanosheet (BNNS)/polyvinyl alcohol (PVA)/lignin nanoparticle (LNP) composite film. The results showed that CNF and LNP had synergistic actions on enhancing the tensile strength, thermal conductivity and stability of the film. The 4 wt% CNF-reinforced composites exhibited the higher through-plane thermal conductivity (up to 1.76 W/mK) than that without CNF (1.44 W/mK), revealing an increase of 22.2% at the same BNNS loading. Meanwhile, the maximum decomposition rate (Rmax) was roughly 0.6%/oC, a decrease of 14.3% compared with the composite film without LNP. Furthermore, the rigidity of composite film was strengthened by incorporating CNF and LNP, the tensile strength of the composite film showed the highest value of 35.0 MPa with 4 wt% CNF and 0.01 g LNP, while this of BNNS/PVA/LNP film and BNNS/PVA/CNF film was only 30.66 MPa and 30.62 MPa, respectively. The green and flexible fabrication approaches will be helpful to build up eco-friendly BN composites with wide applications in thermal management of electronics.

Hemicelluloses were effectively separated using p-toluenesulfonic acid (p-TsOH) treatment at high temperature. High temperature and pressure promoted hydrolysis of hemicellulose, which limited its value upon recovery. In this study, bagasse hemicellulose was separated and extracted by p-TsOH treatment at atmospheric pressure. The effects of temperature, p-TsOH concentration, and time on hemicellulose separation and extraction were investigated. The optimal conditions were 80 °C, 3.0% p-TsOH, and 120 min. The separation and extraction yield of hemicellulose was 73.23% and 36.02%, respectively. Extraction hemicellulose with 95.60% purity was obtained. In addition, the dissolution mechanism of hemicellulose was analyzed. Degradation of β-glycosidic bonds was inhibited. Benzyl ether bond between carbohydrates and lignin was selectively cleaved. The skeleton structure of xylan in hemicellulose was protected while the functional groups of branch chain were severely damaged. It provides a valuable theoretical basis for the efficient separation and extraction of hemicellulose.

Cellulose nanofibrils (CNFs) can prepare flexible nanomaterials with its large aspect ratio. Due to the supramolecular, cellulose fibers are difficultly dissociated to CNFs. In order to destroy this supramolecular structure and prepare high dispersible CNFs, the mechanical and chemical treatments are required. This study examined the effects of mechanical pretreatment and TEMPO-oxidation on the properties of CNFs preparing from bleached softwood kraft pulp. The total yield of TEMPO-oxidized cellulose nanofibrils (TOCNFs) reached 85 %. The morphology, carboxyl group content, crystallinity, surface charge, self-assembling properties, and optical transmittance of the corresponding TOCNFs suspension were investigated. The transmittance of TOCNFs suspension was 95.1 % at 600 nm wavelength and its corresponding ζ- potential was -61.3 mV, indicated that the strong electrostatic repulsion between TOCNFs was the most significant factor on the highly transparent TOCNFs suspension in water. Furthermore, the mostly negative charged TOCNFs obtained by freeze drying assembled into the finest and most uniform networked structure. Such highly transparent, functionalized, selfassembled cellulose nanofibrils are favorable in transparent films, flexible displays and electrochemistry materials.

To face the increasing demand of self-healing hydrogels with high performance for various applications ranging from bioscaffolds, culture matrices to responsive electronic devices, lignin nanoparticle-containing composite hydrogels are assembled via dynamic reversible didiol-borax linkages and linear polyvinyl alcohol (PVA) and cellulose nanofibrils (CNF). Lignin nanoparticles (LNP) acted as nano-spacers to fill the three-dimensional network, leading to enhanced viscoelasticity and thermal stability of hydrogel. With the increased LNP content, composite hydrogel exhibited the highest storage modulus and loss modulus of 8504 Pa and 3260 Pa, respectively, 28 times and 18 times greater than pure hydrogel without LNP. The resulting hydrogel showed porous network structure and excellent recovery behavior under continuous step strain. In general, this work demonstrates a facile approach to transfer nanoscale building blocks to 3D polymeric materials with tunable dynamic rheology properties and may provide a new prospect for the rational design of functional hydrogels for applications that require high rheological property.

Practical production of conductive paper requires the balancing of high electrical conductance, thermal stability and tensile modulus, with cost effectiveness. By utilizing lignocellulose (3.85 ± 0.35% and 17.17 ± 0.62% lignin contents) and graphite as starting materials, a lignocellulose/reduced graphene oxide (LRGO) composite conductive paper is successfully fabricated. The free-standing LRGO paper has a low sheet resistance of 506 ± 34 Ω/sq with a graphene derivative content of ~ 20 wt%. Also high Tonset (312 °C) and T95 (251 °C) are observed, along with a tensile modulus up to 8.36 GPa if ten additional passes of microfluidization are used. Moreover, LRGO paper was used to make active electrodes for a supercapacitor that achieved a specific capacitance of 77.0 F/g. There has been minimal reporting of applying lignocellulose in conductive paper production, so this new method is anticipated to pave the way for developing advanced materials derived from low cost biomass.

Two lignin-containing cellulose nanofibril (LCNF) samples, produced from two unbleached kraft pulps with very different lignin contents, were used to produce reinforced polyvinyl alcohol (PVA) hydrogels. The effects of LCNF loading (0.25–2 wt %) and lignin content on the rheological and mechanical properties of the reinforced hydrogels were investigated. The 2 wt % LCNF-reinforced PVA hydrogels exhibited up to a 17-fold increase in storage modulus and a 4-fold increase in specific Young’s modulus over that of pure PVA hydrogel. Both the mechanical and rheological properties of LCNF-reinforced PVA hydrogels can be tuned by varying LCNF loading and LCNF lignin content. During LCNF production, lignin reduced cellulose depolymerization, resulting in LCNF with high aspect ratios that promoted entanglement and physical bridging of the hydrogel network. Free lignin particles generated during LCNF production acted as multifunctional nanospacers that increased porosity of the hydrogels. Because LCNFs were produced...

Biochar decorated with inorganic magnetic materials has both conductivity and magnetism, and has application prospects in many fields. Synthesis of magnetic biochar composites by in-situ pyrolysis of inorganic precursor (metallic cations or oxide) doping biomass-based composites has been widely reported. However, the chemical composition of biomass is complex and changeable, which is an important and easily neglected factor that affects the inorganic material loading characteristics. Here, we took bamboo as an example biomass material, regulated the chemical components by delignification, and then prepared a series of magnetic biochar by in-situ decoration of inorganic material (Fe3O4) followed by high-temperature pyrolysis phase transition. The lignin content is found to directly affect the absorption efficiency of Fe2+/Fe3+ cations, and then affect the loading amount of magnetic phase as well as the graphitization degree of biochar after carbonization. The formed Fe3C/biochar composites from delignified bamboo with cellulose, hemicellulose and lignin content of 53.8, 39.2 and 7.0 respectively (termed as A4), exhibit excellent EMW absorption capacities with the lowest RL min value of −45.60 dB and a broad maximal f e regions of 5.5 GHz when the thickness is under 2.00 mm. In addition, due to the excellent thermal stability of A4, the EMW absorption performance is maintained at temperature as high as 85˚C. Our work reveals the adsorption mechanism of cations onto biomass materials and puts forward a top-down method for designing inorganic decorated biochar with excellent EMW absorption behavior and thermal stability.