Lignin-containing Cellulose Nanofibrils Research Articles

Mitigating the Water Sensitivity of PBAT/TPS Blends through the Incorporation of Lignin-Containing Cellulose Nanofibrils for Application in Biodegradable Films

Mitigating the Water Sensitivity of PBAT/TPS Blends through the Incorporation of Lignin-Containing Cellulose Nanofibrils for Application in Biodegradable Films

Enzymatic crosslinking of lignin nanoparticles and nanocellulose in cryogels improves adsorption of pharmaceutical pollutants

Pharmaceuticals, designed for treating diseases, ironically endanger humans and aquatic ecosystems as pollutants. Adsorption-based wastewater treatment could address this problem, however, creating efficient adsorbents remains a challenge. Recent efforts have shifted towards sustainable bio-based adsorbents. Here, cryogels from lignin-containing cellulose nanofibrils (LCNF) and lignin nanoparticles (LNPs) were explored as pharmaceuticals adsorbents. An enzyme-based approach using laccase was used for crosslinking instead of fossil-based chemical modification. The impact of laccase treatment on LNPs alone produced surface-crosslinked water-insoluble LNPs with preserved morphology and a hemicellulose-rich, water-soluble LNP fraction. The water-insoluble LNPs displayed a significant increase in adsorption capacity, up to 140 % and 400 % for neutral and cationic drugs, respectively. The crosslinked cryogel prepared by one-pot incubation of LNPs, LCNF and laccase showed significantly higher adsorption capacities for various pharmaceuticals in a multi-component system than pure LCNF or unmodified cryogels. The crosslinking minimized the leaching of LNPs in water, signifying enhanced binding between LNPs and LCNF. In real wastewater, the laccase-modified cryogel displayed 8–44 % removal for cationic pharmaceuticals. Overall, laccase treatment facilitated the production of bio-based adsorbents by improving the deposition of LNPs to LCNF. Finally, this work introduces a sustainable approach for engineering adsorbents, while aligning with global sustainability goals.

One–step synthesis of silver nanoparticles by lignocellulose nanofibrils to obtain antimicrobial hydrogels with accelerated wound healing

Lignin–containing cellulose nanofibrils (LCNF) have attracted extensive attention in the field of antibacterial due to the properties both of lignin and nanofibrils. The evenly distributed nano–lignin in LCNF can reduce Ag+, and the fiber network structure of nanofibrils may prevent the sedimentation of silver nanoparticles (AgNPs), which makes LCNF promising candidates for one–step preparation and deposition of AgNPs. Herein, carboxylated lignocellulose nanofibrils (CLCNF) with high stability were used to initiate the redox reaction. AgNPs (∼10.45 nm) were successfully prepared and homogeneously anchored onto CLCNF (Ag–L NPs–CLCNF). After compositing with polyvinyl alcohol (PVA) and tetracycline hydrochloride (TH), Ag–L NPs–CLCNF constructed a reversible redox quinone/catechol chemistry, imparting hydrogels with long–lasting reproducible adhesion and antimicrobial activity. Moreover, the incorporation of Ag–L NPs–CLCNF significantly improved the tensile strength (30.87 kPa), compressive strength (368.11 kPa) and thermal stability of the hydrogels, and that the Ag–L NPs–CLCNF hydrogel were self–healing. Importantly, the hydrogel containing Ag–L NPs–CLCNF can realize the controlled delivery of TH, giving it excellent antibacterial activity with accompanied good biocompatibility and significantly promoting full–thickness skin wound healing. This work offers a novel idea for preparing antibacterial hydrogels from lignocellulosic nanofibrils and the hydrogels have great application prospects in wound dressing.

Feasibility of lignin-containing cellulose nanofibrils derived from oil palm empty fruit bunch in enhancing the properties of non-wood handsheets

The addition of nanocellulose has been reported to improve the properties of handsheet, mainly the mechanical properties. Nevertheless, nanocellulose addition slows down the water drainage during handsheet making due to the filling effect and increase in fibre bonding, which results in the reduction of handsheet making productivity. In this research, the use of nanocellulose containing residual lignin was hypothesized to improve the productivity in comparison to pure nanocellulose. Lignin-containing cellulose nanofibrils (LCNF) samples having different lignin content were prepared from oil palm empty fruit bunch (OPEFB) through controlled multi-step bleaching process. The LCNF samples were then used in handsheet making with LCNF loading of 1, 2, 4, and 8 wt%. Three LCNF samples were successfully prepared (LCNF-1, LCNF-2 and LCNF-3) with different lignin content at 7.7%, 2.8%, and 0.5%, respectively. LCNF-2 and LCNF-3 had the average width of 31 nm, while LCNF-1 exhibited some portions of incomplete fibrillation which could be attributed to the presence of lignin. The addition of LCNF increased the drainage time compared to the one without LCNF (control), and the drainage time increased with the increase in LCNF loading. Overall results indicated that the addition of 4 wt% LCNF-2 contributed to the best combination in terms of drainage time, tensile index and tear index at 11.3 s, 38.1 Nm/g, and 9.3 mN.m2/g compared to the control sample (8 s, 31.8 Nm/g, and 7.4 mN.m2/g respectively). LCNF-3 gave comparable results, however from sustainability point of view, it is less favoured as it requires more bleaching chemicals to be produced. Findings from this research highlight the importance of lignin in improving the productivity and properties of nanocellulose-incorporated handsheet.

Cellulose nanofibrils as a bio-based binder for wood fiber composite insulation panels with enhanced thermo-mechanical properties for structural wall sheathing applications

A low-density wood fiber insulation panel (WIP) composite was developed with 100 % petrochemical-free, bio-based binder with high mechanical strength, water resistance and thermal insulation properties. This study investigated the manufacturing process of composite WIPs made with mechanical pulp fibers with cellulose nanofibrils (CNFs), lignin-containing CNFs (LCNFs), hybridized CNFs-LCNFs, and CNFs-starch as a binder on different scales and evaluated the effects of binder type and content on the panels’ physical, mechanical, and thermal properties. All panels had excellent thermal resistivity values, which increased with the decrease in density. The WIPs made with LCNFs as binder had lower mechanical properties, but it was possible to replace 20 % CNFs with LCNFs to obtain the same performance as neat CNFs as the binder. Untreated panels had poor water resistance but the water absorption properties were significantly improved with the addition wax. The WIPs made with 5 % and 7.5 % binder content and 2 % wax addition could fulfill the criteria of regular and structural wall sheathing applications, respectively. Overall, the results confirm the potential of CNFs and LCNFs to be used as 100 % bio-based adhesives to produce eco-friendly composite WIPs with excellent thermo-mechanical properties to be used for regular and structural wall sheathing applications.

Microwave-assisted DES fabrication of lignin-containing cellulose nanofibrils and its derived composite conductive hydrogel

Deep eutectic solvents (DES) have been regarded as green solvents in the biorefinery of lignocellulosic biomass, but long duration time has severely limited efficiency. The microwave-assisted DES pretreatment along with enzymatic hydrolysis and high-pressure homogenization process was proposed to produce lignin-containing cellulose nanofibrils (LCNF) from corncob. Benefiting from microwave-assisted DES pretreatment, the duration time was greatly shortened; meanwhile the effects of different kinds of DES on the resultant LCNF were investigated. The results showed that, the microwave-assisted DES fabricated LCNF (M-LCNF) was successfully obtained, exhibiting good nano size, thermal stability, colloidal stability, and fluorescence. M-LCNF was further introduced into phytic acid (PA) enhanced poly(acrylamide-co-acrylic acid) (P(AM-co-AA)) network and constructed composite conductive hydrogels (PLP). The obtained hydrogels exhibited good mechanical strength, UV blocking ability, fluorescence, and conductivity. A simple battery assembled with the resultant PLP as electrolyte had an out voltage of 2.41 V. The composite conductive hydrogel showed good sensing performance towards different stimuli (e.g., stretching and compression) and human motions in real time. It is expected that this research would provide an alternative way for green fabrication of LCNF and potential application of LCNF in flexible sensors.

Sustainable route to prepare functional lignin-containing cellulose nanofibrils

With nano-dimension, high aspect ratio, and high mechanical properties, cellulose nanofibrils (CNFs) are emerging sustainable nanomaterials with potential applications in films and composites. However, their preparation often involves a series of chemical treatments such as delignification, bleaching and harsh chemical pretreatments, and treats lignin as waste. Herein, we report a sustainable method to prepare high-quality lignin-containing cellulose nanofibrils (LCNFs) from bamboo chips, using a one-step maleic anhydride esterification treatment without any toxic organic solvent or catalyst. The resultant LCNFs have high lignin content (24%), high surface charge (2.25 mmol/g), fine diameter (∼2.5 nm), and high aspect ratio (>400). These superior properties can be translated into the corresponding nanopaper films with high optical transmittance (85% at 600 nm), UV shielding (<10% transmittance at 200–350 nm), hydrophobicity (water contact angle 75°), thermal stability (maximal weight loss temperature at 338 °C), and mechanical properties. Importantly, such films show the best reported tensile strength (290 MPa) among all the LCNF films, and it still outperforms conventional CNF films after 5 rounds of recycling. Furthermore, as sustainable nanofillers, such LCNFs can be directly incorporated into a hydrophobic polyester matrix, and significantly enhances the UV shielding and mechanical properties of the final nanocomposites. Altogether, with eco-friendly production and multiple functions, these LCNFs are a new class of nanocelluloses with high industrial relevance.

High-Lignin-Containing Cellulose Nanofibrils from Date Palm Waste Produced by Hydrothermal Treatment in the Presence of Maleic Acid.

Lignin-containing cellulose nanofibrils (LCNFs) have attracted great attention because the presence of lignin brought additional merits to cellulose nanofibrils including hydrophobicity, ultraviolet (UV)-shielding capacity, and reduced water sensitivity. In the present work, LCNFs with lignin content up to 21 wt % were prepared with a high yield exceeding 70 wt %, from neat date palm waste, by a hydrothermal treatment (HTT) at 120-150 °C in the presence of 20-30 wt % maleic acid, followed by high-pressure homogenization. The chemical composition, degree of polymerization, morphology, and colloidal and rheological properties of the LCNFs were investigated to understand how the HTT in the presence of MA affected the properties of the resulting LCNFs. Nanopapers prepared from the LCNF suspensions exhibited mechanical properties lower than those from lignin-free CNF-based nanopapers, yet with decreased hydrophilicity. A mechanism explaining how the HTT in the presence of MA facilitated the disintegration of the biomass into nanoscale material was proposed. Overall, the present work demonstrated a feasible and scalable approach for the sustainable production of LCNF suspensions from neat agricultural residues, with a high yield and a high lignin content, without any need to perform a preliminary partial delignification.

Green, one-pot biomass hierarchical utilization strategy for lignin-containing cellulose nanofibrils and fractionated lignin preparation

The recalcitrant nature of plant cells makes biomass hierarchical utilization challenging. Here we report a green, one-pot strategy to achieve fractionation of sugarcane pith cellulose and lignin. Lignin-containing cellulose nanofibrils (LCNFs) and fractionated lignin (by tailored choline chloride and oxalic acid-based deep eutectic solvents (DESs) and ultrasonic nanofibrillation pretreatments) were studied. The obtained LCNFs had a well-independent structure and uniform size distribution (5.05–6.88 nm in diameter). Lignin fractionated by diol acid DES (DADES) exhibited a relatively homogeneous molecular weight (Mw, 2013–2827 g/mol), reduced lignin heterogeneity, and condensation under acidic conditions. Besides, multi-functional LCNF papers were prepared by vacuum filtration of their suspensions and had excellent bio-disintegration capability, water resistance, UV-shielding performance, and thermal stability. This study demonstrated that DADES enables hierarchical biomass utilization and successful production of high-value-added building blocks, such as LCNF and fractionated lignin.

Lignin/polypyrrole interpenetrating networks decorated Lignin-containing cellulose nanofibril composite membrane for High-performance supercapacitors

Lignin-containing cellulose nanofibrils (LCNFs) are emerging and promising multifunctional nanomaterials for economical and eco-friendly flexible supercapacitors (SCs). However, the strengthening mechanism of lignin on the capacitive and mechanical performance of LCNF-based nanocomposite electrodes has not been deeply studied. Herein, a mechanically strong nanocomposite electrode with excellent capacitive performance was fabricated by decorating a sodium lignosulphonate/polypyrrole (LS/PPy) interpenetrating network onto LCNFs, the relationship between lignin content, LCNFs morphology and electrodes performance was systematically investigated. Results showed that lignin could effectively strengthen the capacitive and mechanical performance of the electrodes via providing pseudocapacitance generated by the reversible conversion of quinone/hydroquinone and controlling the fibrillation degree of LCNFs. With decreasing the lignin content, LCNFs gradually transformed from nanofibril bundles to uniform nanofibrils, forming an electrode with hierarchical porous structure, highly interconnected conductive network, high active site exposure rate and excellent capacitive and mechanical performance. However, insufficient lignin could weaken the capacitive and mechanical performance of the electrodes via reducing quinone/hydroquinone content, electrodes porosity and LCNFs strength. Therefore, electrodes with lignin content of 11.4% displayed excellent tensile strength (20.46 MPa) and areal specific capacitance (2567 mF cm−2, 1 mA cm−2). The assembled all-solid-state supercapacitor (ASSC) delivered high coulombic efficiency (∼98%) and energy density, 88.6 μWh cm−2 (499.9 μW cm−2) and 1.74 mWh cm−3 (9.8 mW cm−3) for areal and volumetric energy (power) density, respectively. This work systematically reveals the strengthening mechanism of lignin on the capacitive and mechanical performance of the electrodes and provides theoretical guidance for constructing high-performance LCNF-based nanocomposite electrodes.

Valorization of olive leaf waste as a new source of fractions containing cellulose nanomaterials

The olive oil activity generates annually a huge amount of biomass waste from the pruning action of the tree and fruit harvesting, including thin woody branches and leaves. In an effort toward more sustainability in the lignocellulosic biorefinery of olive waste activity, nanocelluloses (NCs) were produced from the solid residues remaining after the extraction of biological active compounds from the leaves. Fractions containing cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and lignin-containing cellulose nanofibrils (LCNFs) were prepared and characterized in terms of morphology, chemical composition, thermal stability, colloidal properties, and crystallinity. The reinforcing capability of the different fractions was evaluated in nanocomposite films made of an acrylic matrix incorporating different NC contents. Dynamic mechanical analysis (DMA) and tensile testing of the films were used to compare the reinforcing effect of the NCs. Although CNCs displayed the highest reinforcing effect based on the weight content, LCNFs and CNFs demonstrated also a reinforcing effect, which is higher when normalized with the cellulose content. Compared to CNFs and CNCs, LCNFs displayed a lower hydrophilic character confirmed by contact angle measurement, and had better thermal stability. This work demonstrated the potential use of the solid waste from olive leaves as a new source for biobased nanoparticles containing lignin, hemicellulose components, and cellulose nanofibrils. Beside the high content in bioactive polyphenol compounds that can be extracted from olive leaves, the conversion of the residual biomass can contribute to increasing the circularity and sustainability of olive oil activity.

Leakage-free porous cellulose-based phase change cryogels for sound and thermal insulation

Leakage-free phase change materials (PCM) are used as passive energy storage systems that thermoregulate indoor environments. In this research, we synthesized highly porous hybrid materials based on non-covalent physical interactions between (poly)ethylene glycol (PEG) and modified cellulose nanofibrils (CNF), namely lignin-containing CNF (LCNF) or acetylated CNF (ACNF). The PEG/CNF hybrid, termed phase change nanohybrids (PCN), were ultra-lightweight (0.022–0.043 g/cm3), mechanically resilient, and displayed a high latent energy storage, up to 204 J/g. The PCN systems (specific heat capacity as high as 2.24 J/g K) were effective in thermal regulating 2.23 °C with a 1 mm thickness coverage while maintaining thermal stability. The PCN also demonstrated favorable thermal management under excess solar heating, providing 33.5 °C of insulative protection with a 1.5 cm thick system. The PCNs have exceptional acoustic absorbance (100% absorbance for 1600 Hz and 50% at lower frequencies, 500 Hz). Trace metal oxide (TiO2) nanoparticles improved the PCN thermoregulating abilities, revealing desirable opportunities in multi-functional applications. Our biobased PCN is a promising insulation and passive energy storage alternative for thermal protection in smart building, electronic, packaging, energy storage system and aerospace sectors.

Complete valorization of bamboo biomass into multifunctional nanomaterials by reactive deep eutectic solvent pretreatment: Towards a waste-free biorefinery

The introduction of nanotechnology into conventional biorefinery will facilitate complete valorization of lignocellulosic biomass. In this work, a microwave-assisted deep eutectic solvent (DES) pretreatment was developed for one-pot fractionation of bamboo biomass into three scalable fractions (cellulose-rich residue, lignin and recovered DES), which were then respectively upgraded to three value-added bio-based nanomaterials, namely lignin-containing cellulose nanofibrils (LCNFs), lignin nanoparticles (LNPs) and carbon quantum dots (CDs). After the mild and rapid DES pretreatment (130 °C, 20 min), 51.0% cellulose-rich residue was recovered accompanied by 90.6% delignification ratio. The cellulose-rich residues were mechanically fibrillated into LCNFs with a width of 5–20 nm. In-situ esterification of carboxylic acid groups from DES with cellulose hydroxyl groups improved the hydrophobicity of LCNFs. The LCNFs film prepared exhibited excellent hydrophobic (water contact angle of 103.3°). In-situ esterification, condensation and cleavage reactions of lignin during DES fractionation enhanced its amphiphilicity and facilitated lignin self-assembly into LNPs with diameters of 30–75 nm. Furthermore, using the recovered DES as carbon precursors, CDs were successfully prepared by a typical hydrothermal method, which provides a new approach for the disposal of waste DES. In short, the proposed waste-free biorefinery scheme realizes the complete valorization of bamboo biomass into bio-based multifunctional nanomaterials, which can be further applied in various downstream fields.

Turning Recycled Cardboard Container-Derived Lignin-Containing Cellulose Nanofibrils into a Robust Gas Barrier UV-Shielding Film

Self-standing cellulose nanofibril (CNF) films are regarded as one of the promising alternatives to current petroleum-based packaging materials mostly due to their ability to form dense self-assembled structures exhibiting high gas barrier properties. Nonetheless, one of the major obstacles to the commercialization of these materials in packaging applications is the high cost of raw materials and production energy. In this study, we created self-standing films of lignin-containing cellulose nanofibrils (LCNFs) derived from a recycled old corrugated cardboard (OCC) pulp that costs less than bleached softwood Kraft (BSK) pulp and requires half as much energy for refining to obtain the same quality of material. The low zeta potential (−3.83 mV) of OCC-derived LCNFs (OCC-LCNFs) resulted in aggregation of the fibrils in aqueous suspension, leading to considerable unpredictability in oxygen permeability (OP) values (coefficient of variation 36%). The addition of 3 wt % (based on the dry weight of LCNFs) carboxymethyl cellulose lowered the coefficient of variation to 16% with an average OP of 1478 (cc.μm/m2.atm.day) at 80% relative humidity. Because the OP was higher than that of the CNF film made from BSK-derived CNF (BSK-CNFs), we demonstrated that ionic crosslinking with trivalent aluminum ion or covalent crosslinking with polyamide epichlorohydrin decreased the OP by 30% at 23 °C and 80% relative humidity while also significantly enhancing the tensile strength and modulus. In addition, the presence of lignin in OCC resulted in a relatively lower water vapor permeability value in OCC-LCNF films compared to BSK-CNF films. Moreover, OCC-LCNF films showed complete UV-shielding (200–400 nm) property. Overall, this work provides a new opportunity to exploit a recycled and inexpensive source of CNFs to produce robust gas barrier materials for packaging applications.

Lignin-Containing Cellulose Nanofibrils from TEMPO-Mediated Oxidation of Date Palm Waste: Preparation, Characterization, and Reinforcing Potential.

Lignin-containing cellulose nanofibrils (LCNFs) have emerged as a new class of nanocelluloses where the presence of residual lignin is expected to impart additional attributes such as hydrophobicity or UV-absorption. In the present work, LCNFs with a lignin content between 7 and 15 wt% were prepared via a TEMPO-mediated oxidation as chemical pretreatment followed by high-pressure homogenization. The impact of the carboxyl content (CC) on the properties of the resulting LCNF gel, in terms of lignin content, colloidal properties, morphology, crystallinity, and thermal stability, were investigated. It was found that lignin content was significantly decreased at increasing CC. In addition, CC had a positive effect on colloidal stability and water contact angle, as well as resulting in smaller fibrils. This lower size, together with the lower lignin content, resulted in a slightly lower thermal stability. The reinforcing potential of the LCNFs when incorporated into a ductile polymer matrix was also explored by preparing nanocomposite films with different LCNF contents that were mechanically tested under linear and non-linear regimes by dynamic mechanical analysis (DMA) and tensile tests. For comparison purposes, the reinforcing effect of the LCNFs with lignin-free CNFs was also reported based on literature data. It was found that lignin hinders the network-forming capacity of LCNFs, as literature data shows a higher reinforcing potential of lignin-free CNFs. Nonetheless, the tensile strength of the acrylic matrix was enhanced by 10-fold at 10 wt% of LCNF content.

High performance and multifunctional Janus bio-nanocomposite film for underwater actuators with excellent sensitivity and controllability

Stimuli-responsive materials have been increasingly explored to construct actuators and develop soft robots. Herein, one strategy via regulating lignin-containing cellulose nanofibrils (LCNF) distribution in PVA network followed by alkaline treatment (AT) and pre-stretching to fabricate bio-nanocomposite derived Janus films with stimulus response is proposed. LCNF/PVA-AT film displays obvious asymmetric structure, good mechanical properties, and water-resistance. Based on Janus structure and Hofmeister effect of PVA in salt solution, the applied pre-stretching treatment further enables the as-prepared LCNF/PVA-AT film with an excellently smart and controllable responsiveness to salt solutions. In addition, by adjusting some factors including length–width ratio of the film, salt type and concentration, the deformation degree and response/recovery time of LCNF/PVA-AT film and its based actuators can be controllably designed. The study will enrich the development of green, sustainable and biodegradable polymers derived Janus films, and expand their wide potential applications in multifunctional actuators.

Development of Lignin-Containing Cellulose Nanofibrils Coated Paper-Based Filters for Effective Oil-Water Separation.

New methods of oil-water separation are needed as industrialization has increased the prevalence of oil-water mixtures on Earth. As an abundant and renewable resource with high oxygen and grease barrier properties, mechanically refined cellulose nanofibrils (CNFs) may have promising applications for oil-water separations. The unbleached form of these nanofibrils, lignin-containing CNFs (LCNFs), have also been found to display extraordinary barrier properties and are more environmentally friendly and cost-effective than CNFs. Herein, both wet and dry LCNF-modified filter papers have been developed by coating commercial filter paper with an LCNF suspension utilizing vacuum filtration. The LCNF-modified filters were tested for effectiveness in separating oil-water emulsions, and a positive relationship was discovered between a filter's LCNF coat weight and its oil collection capabilities. The filtration time was also analyzed for various coat weights, revealing a trend of high flux for low LCNF coat weights giving-way-to predictions of a coat weight upper limit. Additionally, it was found that wet filters tend to have higher flux values and oil separation efficiency values than dry filters of the same LCNF coat weight. Results confirm that the addition of LCNF to commercial filter papers has the potential to be used in oil-water separation.

New ternary deep eutectic solvents with cycle performance for efficient pretreated radiata pine forming to lignin containing cellulose nanofibrils

Ternary deep eutectic solvents (TDESs) as a new class of solvents play a key role in fabrication of lignin containing cellulose nanofibrils (LCNF), however, current work requires a considerable time and thus limits industrial application of TDES. Herein, a novel strategy was proposed to produce lignin containing cellulose nanofibrils (LCNF) by TDESs based on benzyltrimethylammonium chloride (BTMAC), formic acid (FA), and maleic acid (MA). The TDESs could remove 87.80% of lignin and 89.15% of hemicellulose from Radiata Pine while most of the cellulose reserved under optimum pretreatment conditions (TDES = 100 wt%, T = 130 °C, t = 1.5 h). Benefiting from the increase in cellulase accessibility, desired sugar yield of 98.9% was obtained. Moreover, the proposed TDESs could be regarded as a green medium for the production of containing cellulose nanofibrils (LCNF) in which lignin has been esterified. The LCNF displayed a well-individualized structure with a wide size distribution (32.3–146.9 nm), which was closely associated with lignin content. 13C−1H HSQC 2D NMR test was performed to illustrate the molecular − structural features of lignin and polysaccharide in LCNF. In addition, the self-standing LCNF films exhibited excellent UV-blocking, higher thermal stability, and mechanical strength. Most importantly, LCNF films showed strong barrier property to oil and air owing to lower surface free energy and smaller pore structure. Briefly, this work highlights the pretreatment performance of TDESs for cascade utilization of lignocellulosic biomass to high-value products.

The reinforcing effect of lignin‐containing cellulose nanofibrils in the methacrylate composites produced by stereolithography

AbstractLignin‐containing nanocellulose has been used as a potential reinforcement in the three‐dimensional (3D) printed materials due to its high aspect ratio and favorable compatibility with 3D printed polymer matrix. However, lignin‐containing cellulose nanocrystal (L‐CNC) only performed its reinforcement at elevated temperature during postcure process. This not only complicates the 3D printing process, but also increases the energy consumption of 3D printing. Therefore, in this study, we applied the lignin‐containing cellulose nanofibrils (L‐CNF) to reinforce the 3D printed methacrylate (MA) resin and the reinforcing mechanism of L‐CNF with a simple material process was investigated. Mechanical, thermal, and rheological properties of the 3D printed composites were systematically analyzed. It was observed that the mechanical and thermal properties of 3D printed composites were enhanced with the addition of L‐CNF due to its distinguished characters of surfacial‐coated lignin and high aspect ratio, which increase the mechanical interaction between L‐CNF and MA matrix.

Tailored production of lignin-containing cellulose nanofibrils from sugarcane bagasse pretreated by acid-catalyzed alcohol solutions

In this study, sugarcane bagasse was pretreated with acid-catalyzed alcohols, i.e., ethanol (AE), ethylene glycol (AEG) and glycerol (AG) to prepare pulps for producing lignin-containing cellulose nanofibrils (LCNF) with tailored properties, such as hydrophilicity/hydrophobicity and dispersion stability. The results showed that AG-LCNF had the highest lignin content of 16% but relatively low hydrophobicity while AE-LCNF had a low lignin content of 11% but the highest hydrophobicity. LCNF diameter distribution, crystallinity, zeta potentials and thermal stability were also determined to understand the effects of pretreatment solvent. NMR analyses revealed that alcohols modified lignin at α-position by etherification and γ-position by esterification of aliphatic chains, subsequently affecting lignin oxidation by TEMPO in the LCNF production processes, LCNF properties and LCNF dispersion in different solvents. This study provided fundamental information in the design and tailored production of LCNF for various applications, such as manufacturing polymer composites and Pickering emulsions.