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In this study, a flexible sensor is successfully fabricated using self‐healing nanocomposite hydrogels for monitoring human movement. The eco‐friendly cellulose nanocrystals (CNCs) are used as nano‐reinforcing materials, and the mechanical properties and self‐healing efficiency of the materials are improved. The self‐healing efficiency of hydrogels are realized by introducing a variety of reversible non‐covalent interactions such as hydrogen bonding, borax chelation, and metal coordination. Notably, the mechanical strength and self‐healing efficiency of these nanocomposite hydrogels can reach 2.8 MPa and 89.9%, respectively. Importantly, these self‐healing nanocomposite hydrogels have been widely used in wearable flexible sensors to achieve high sensitivity to large‐scale human movement. It is of great significance to design functional materials with good biocompatibility, sensitivity, and mechanical strength for wearable sensors. [ABSTRACT FROM AUTHOR]

Cellulose nanomaterials are derived from the most abundant biopolymer on earth, and are gaining importance in the shift from oil-based materials to sustainable alternatives. To facilitate this, sustainable methods to modify these renewable nanostructured materials must be explored, as surface modifications are prerequisite for many nanocellulose applications. Here, we present a solvent-free method for the surface modification of cellulose nanocrystals, encompassing mechanochemistry to convert uncharged or charged CNCs to tosylated CNCs, and for the subsequent versatile nucleophilic substitution with amines and esters. Systematic screening of the reaction parameters revealed key variables - milling time, base type and amount, for tosylation to take place during 60 minutes of ball-milling without major changes to CNC morphology and crystallinity. Both step-wise and one-step in situ nucleophilic substitution of the tosyl CNCs was successful with amine and ester modification. Our results demonstrate how fine-tuning the parameters of solvent-free methods can lead to fast and environmentally benign reactions on cellulose nanomaterials while retaining their structure on the nanoscale. [ABSTRACT FROM AUTHOR]

Biomimetic optical devices based on cellulose nanocrystals with tunable structural colors have received significant attention recently. However, the limited ability to control multicolor separation beyond simple single‐color modulation restricts its practical applications. Here, a diversified multicolor separation strategy for the cholesteric phase cellulose composite (CPCC) is presented. The CPCC is prepared by integrating a high‐concentration self‐assembled hydroxypropyl cellulose with a cross‐linked poly(acrylic acid‐acrylamide) (P(AA‐AM)) network. By adjusting the cross‐linking degree of P(AA‐AM) in CPCC, Thermally induced multicolor separation is achieved from a homochromatic state at room temperature to multicolor patterned display at elevated temperatures. Furthermore, by utilizing the electric heating effect of conductive carbon oil, the multicolor separation under low voltage is achieved, and based on this, pixelated electro‐thermochromic displays are developed. Additionally, magneto‐thermal multicolor separation induced by introducing FeNi3 nanoparticles is investigated with efficient magnetic induction heating ability into CPCC. The multicolor separation effect is further improved by pixelated distribution of FeNi3 nanoparticles and adjusting the concentration of FeNi3 in each pixel. Finally, thermochromism, electro‐thermochromic, and magneto‐thermochromic functionalities are integrated into the CPCC, achieving advanced multilevel information encryption. This multilevel approach of controlling multicolor separation significantly enhances the functionality of nanocellulose in various potential photonic applications. [ABSTRACT FROM AUTHOR]

The interaction of circularly polarized (CP) light with chiral matter at different scales opens several possibilities of light manipulation in photonic and electronic devices. Here it is shown that in a multilayer architecture, it is possible to take advantage of the polarization‐selective reflection of the nematic arrangement of cellulose nanocrystals and the strong intrinsic CP luminescence (CPL) of the various bands of chiral Eu complexes. In this way, both the intrinsic CPL and total emission of the complex are modified depending on the enantiomer applied and on the detection geometry. This concept may apply for polarization control in electronic and photonic devices and polarized optical cavities. [ABSTRACT FROM AUTHOR]

Decorating cellulose nanocrystals(CNC) with nanoparticles(NPs) allows to engineer novel CNC/NPs composites for advanced technologies and applications. NPs are well‐known for their unique and highly efficient properties. However, NPs present challenges and limitations due to their aggregation, non‐uniform growth, size distribution, and nanotoxicity. CNC surface overcomes most of these drawbacks by providing an attractive matrix/template to grow NPs of desirable morphology, distribution, and functionality. CNC has distinctive properties such as biodegradability, high surface area, low cost, good mechanical strength, surface functionality, and chiral nematic self‐assembly. CNC/NPs composites combine the unique properties of both CNC and NPs. This review highlights the unique characteristics of CNC, NPs, and their composites for energy, catalysis, and biomedical applications. First, different production methods for CNC with their effect on morphology, crystallinity index, and yield are presented. Both organic and inorganic NPs are used to decorate either a pristine or a functionalized CNC surface. In situ nucleation and growth methods are compared with the direct incorporation of pre‐formed NPs on the CNC surface. Applications of CNC/NPs composites are reviewed for energy storage material, conductive materials, catalysts, antibacterial agents, biosensors, and bioimaging. Finally, the current challenges and perspectives are presented for unleashing new possibilities in developing functional CNC‐NPs composites. [ABSTRACT FROM AUTHOR]

Composite electrospun nanofibers based on silk fibroin (SF), aminated reduced graphene oxide (NH2rGO), and oxidized-cellulose nanocrystals (AD-CNCs) were designed to promote the healing process by electrical conductivity. In this respect, CNCs were produced from cotton cellulose and oxidized in the presence of sodium periodate, and reduced GO was synthesized and functionalized with amine with p-anthranilic acid via an esterification reaction. Then the crosslink was prepared by the Schiff-base reaction between oxidized CNCs and NH2rGO. Electrospun nanofibers were prepared from silk fibroin, previously prepared from Bombyx Mori cocoons, AD-CNCs, and different ratios of NH2rGO. The SF/AD-CNCs/NH2rGO nanofibrous scaffold presented multiple propitious characteristics for cell proliferation and wound dressing including low cytotoxicity, a hydrophilic surface, thermal stability, and degradability. The physicochemical evaluations showed that with increasing the NH2rGO content, hydrophilicity and electroconductivity of nanofibers increased. The SF/AD-CNCs/NH2rGO biodegradable conductive scaffold with 2.5% NH2rGO content showed favorable nanofibrous structure, supporting and stimulating fibroblast cell proliferation and attachment. The SF/AD-CNCs/NH2rGO nanofibrous scaffold demonstrates the application potential in wound healing management. [ABSTRACT FROM AUTHOR]

Direct ink writing is especially relevant to the biomedical field due to the customizable extrusion and the possibility of creating pre‐designed architectures. Abundant natural polymers are sustainable and biocompatible alternatives to synthetic and persistent polymers. The printing of pure nanocellulose suspensions proves difficult due to low solid loadings, high shrinkage, as well as non‐fitting rheology. Emulsion gels (emulgel) alternatives gain attention in the field owing to their favorable viscoelastic properties and the possibility of creating multiphase systems. The authors’ sulfur‐free cationic cellulose nanocrystals (CNC) of low degree of substitution enable straightforward deployment in Pickering emulsions. An emulgel ink co‐stabilized by cationic CNC and α‐cyclodextrin is introduced as an interfacial inclusion complex. All ink components are natural and biodegradable compounds. The produced emulgel inks allow for high fidelity printing and minimum shrinkage upon drying that relaxes the need for supports, even in complex overhanging structures. A low yield stress (230–270 Pa) facilitates the inclusion of cells for biomedical applications into the formulation. The emulgel can be tuned to the desired rheological properties and be equipped with both polar and apolar compounds due to the biphasic system, making it a promising platform for biocompatible additive manufacturing. [ABSTRACT FROM AUTHOR]

Nylon nanocomposites were prepared by in‐situ ring‐opening polymerization to overcome the problem of poor properties due to the uneven dispersion of the nanoparticles by the traditional melt blending. This high‐performance polyamide 6 (PA6) nanocomposites with high dispersion and strong interface was prepared by grafting PA6 onto the surface of cellulose nanocrystals (CNC). The micromorphology, mechanical, crystalline and thermal properties of the composites were also investigated. Firstly, the hydroxyl group on the surface of CNC reacted with the para isocyanate of toluene diisocyanate (TDI), and the remaining ortho isocyanate was blocked by caprolactam to prepare CNC grafted with caprolactam (CNC‐g‐CL). Then CNC‐g‐CL was used as an activator to prepare cellulose nanocrystal grafted with polyamide 6 (CNC‐g‐PA6) composites by the ring‐opening polymerization of caprolactam on the CNC. The effects of different reaction temperatures, solvent amounts and molar ratios on the grafting rate of CNC‐g‐CL were investigated. The results showed that the highest grafting rate of CNC‐g‐CL with 66.7% was achieved at a reaction temperature of 45°C, 0.1 g/mL CNC in toluene, and a molar ratio of 6 for TDI/CNC. Further, different CNC‐g‐PA6 composites prepared from different CNC content and activator content were explored. For CNC‐g‐PA6 composites, CNC was uniformly dispersed in the PA6 matrix and had a good compatibility with the matrix. CNC exhibited significant reinforcement in the composites with a tensile strength of up to 108 MPa. In addition, the glass transition temperature of CNC‐g‐PA6 was increased to 92°C, which significantly improved the heat resistance of the new composites. Highlights: Effects of reaction condition of CNC and TDI on DSTDI and DSCL were studied.Effects of CNC and activator content on CNC‐g‐PA6 properties were studied.CNC is uniformly dispersed in PA6 with average particle size less than 1 micron.The nylon matrix was significantly strengthened by the addition of CNC.The addition of CNC significantly improved the heat resistance of the composites. [ABSTRACT FROM AUTHOR]

During the last decades, the interest in the development of materials fully or partially biobased has increased. Polyurethanes are extensively used in a wide range of industries because of their versatility. The present work explores the synthesis of partially biobased poly(urethane‐urea) (PUU) composites employing soy‐based polyol (SPO) and cellulose nanocrystals (CNC). The latter were incorporated during the synthesis (in‐situ) or after the synthesis (ex‐situ). The possibility of a technological application as coatings was investigated for the designed materials. Polycaprolactone diol was used as a soft segment due to high functionality of the soy‐based polyol. The physicochemical, thermal and mechanical properties of the prepared matrices were analyzed. Poly(urethane‐urea)s containing up to 20% by weight of biobased polyol showed coating application potentiality. Compared to a polycaprolactone‐based polyurethane, the utilization of the bioprecursor enhanced light absorption in the UV–Vis region. In addition, partially biobased systems showed better mechanical resistance (Young's modulus increased up to 6 times) and hydrophobicity (sweeling decreased from 60 to 8 per cent by weight). Incorporation of cellulose nanocrystals affected primarily the physicochemical and rheological properties of dispersions. Regarding coating properties, nanocrystals utilization complemented the soy‐based polyol improving the performance of the films. Furthermore, the incorporation route affected the dispersions and films properties. Highlights: SPO was incorporated up to 20 per cent by weight in PUU composites.Higher SPO contents improved UV–Vis absorption and tensile strength of films.Films were less hydrophilic as more SPO was incorporated.The CNC‐reinforcement was complementary to the utilization of the SPO.CNC incorporation route affects properties and performance of the coatings. [ABSTRACT FROM AUTHOR]

Designing low-energy consumption, highly sensitive, and stable room temperature (RT) gas sensors based on green and renewable materials is both significant and attractive. Cellulose nanocrystals (CNC), eco-friendly materials extracted from the most abundant natural polymer, cellulose, possess unique characteristics, including one-dimensional nanorod structures, abundant functional groups, large specific surface area, a high aspect ratio, and a point-to-point conductive network structure. These characteristics have shown great potential in the development of high-performance gas sensors. Herein, a magnificent C–Cu2O/CuO nanocomposite is facilely synthesized from a CNC/Cu2+ aerogel freeze-drying method followed by subsequent heat treatment. By adjusting the degree of annealing, the material forms a heterogeneous structure that is conducive to enhancing its sensing properties. Structural characterization confirms that the heterostructured Cu2O/CuO hollow nanospheres are formed and embedded within the CNC-derived carbon, providing abundant active sites for gas molecule adsorption, thereby ensuring high performance. The as-prepared sensor exhibits high sensitivity (∼1801 toward 10 ppm), excellent linearity, and selectivity to NO2 at 25 °C. Intriguingly, the calculated limit of detection (LOD) of the sensor, which integrates the merits of CNC and heterostructured Cu2O/CuO, is as low as 0.15 ppb. Therefore, it is believed that the proposed idea of constructing nanostructures provides a universal strategy for developing other types of carbon-supported porous metal oxide nanocomposites. [ABSTRACT FROM AUTHOR]

Blending modification is used to improve the hemocompatibility of cellulose acetate (CA) dialysis membranes while endowing the CA membrane with endotoxin scavenging and antibacterial capabilities. First, polydopamine (PDA) and polyethylenimine (PEI) are used as negatively charged and positively charged moieties, respectively, together with cellulose nanocrystals (CNCs) to construct mixed charge CNCs (PEI‐PDA@CNCs). Then PEI‐PDA@CNCs is blended with the CA casting solution, and the modified CA dialysis membrane is prepared through a phase inversion process. Through biocompatibility, adsorption, antibacterial, and filtration experiments, various properties of PEI‐PDA@CNCs modified CA membrane (PDCA) are systematically tested. The results show that the PDCA membrane exhibited good blood compatibility and noncytotoxicity. At the same time, the PDCA membrane has antibacterial properties and excellent endotoxin adsorption capacity. Compared with the CA membrane, the clearance rates of PDCA membrane for Staphylococcus aureus and Escherichia coli reach 54.0% ± 1.5% and 52.9% ± 5.9% respectively. In the dynamic adsorption experiment, the adsorption capacity of PDCA membrane for endotoxin increases to 2322.1 ± 45.9 EU/g. The research results indicate that PEI‐PDA@CNC‐modified multifunctional CA membrane with endotoxin adsorption and antibacterial properties has potential application prospects in the fields of hemodialysis and blood purification. [ABSTRACT FROM AUTHOR]

Summary This work investigated the effect of bacterial cellulose nanocrystals (BCNCs)‐gelatin (GelA)/cinnamon essential oil (CEO) emulsion coatings (BCNCs‐GelA/CEO) on the shelf‐life extension of button mushrooms (Agaricus bisporus). CEO loadings between 1200 and 2400 μL/L were used in the coatings applied on the mushrooms' surface. The overall quality of coated mushrooms was monitored over 15 days of cold storage (4 ± 0.5 °C). Regardless of the storage time, using the highest amount of CEO within the coating formulation minimised the impact on tested parameters (weight loss, firmness, percentage of opened caps, total soluble solids, content of ascorbic acid and soluble protein, PPO/POD enzymatic activity) as compared to control samples. Interestingly, a linear relationship (R2 = 0.96 on average) between CEO concentration and the respiration rate of coated mushrooms was disclosed. Overall, this study pinpointed the capability of BCNCs‐GelA/CEO coatings to delay the aging process of button mushrooms under cold storage. Our findings could be applied to address the issue of food losses, highlighting the positive role of coating technology in enhancing the efficiency of the early stages of the food supply chain, especially in the case of button mushrooms. However, an assessment of the impact of the concentration of other coating components (BCNC and fish gelatin) on the shelf‐life extension of button mushrooms, as well as an evaluation of the coating's effectiveness in prolonging the shelf‐life of other food items, particularly non‐respiring products, is necessary to widespread the applicability of the proposed technology. [ABSTRACT FROM AUTHOR]

This study investigated the use of cellulose nanocrystals (CNC)/chitosan (Chit) polyelectrolyte complex as a stabilizing agent for Pickering emulsions. We demonstrated that chitosan reduces the surface charge of CNC improving the emulsification process. An optimal stabilizing complex containing 1% chitosan results in emulsions with minimal zeta potential (3.2 ± 0.3 mV), droplet size (2.8 ± 0.8 μm), and creaming index (19.8 ± 1.0%) values, along with high stability during storage, a change in pH, and high centrifugal forces (up to 2000 g). The study also showed that the maximum neutralized surface charge of the CNC in the CNC-Chit complex allows for effective adsorption on the surface of sunflower oil droplets, producing a denser stabilizing layer with a smaller droplet size. Additionally, chitosan addition is linked to improved stability and higher viscosity, with little dependence on ionic strength and temperature. Potentiometric titration revealed that compared with sulfated CNCs, five times less chitosan is needed to neutralize the negative surface charge of acetylated CNC. The wettability of a hydrophilic surface depends on the surface charge of the complex, and the wettability and adhesion performance increase with increasing chitosan content. Additionally, we showed that tuning the stabilizer composition can change the bioaccessibility of lipophilic compounds during oral administration. [ABSTRACT FROM AUTHOR]

The electrochemical performance of lithium-ion batteries (LIBs) depends dramatically on the composition, microstructure, and morphology of anode materials. The development of carbon nanotube (CNT)-based anode materials is of great significance. However, the easy agglomeration and winding of CNTs hinder the embedding of lithium ions (Li+), leading to the failure of the battery at a high rate when the CNT film is solely used as anode. Herein, binder-free hybrid films of CNTs and carbon nanocoils (CNCs) were fabricated by the facile vacuum-assisted filtration method. The uniform dispersion of helical CNCs in the densely compacted CNTs results in a large number of passways and space to achieve rapid charge transmission. It is found that the storage capacities of Li+ are strongly dependent on the mixing ratio of CNTs and CNCs. The highest storage capacities of Li+ are obtained in the CNT-CNC film at a mixing ratio of 4:1. The CNT-CNC film electrode still has a charge and discharge capacity of 300 mAh/g even at a high specific current of 800 mA/g, while the CNT film electrode has 150 mAh/g. These results indicate that the CNT-CNC hybrid film is a promising material to be used as binder-free anodes for LIBs. [ABSTRACT FROM AUTHOR]

Here, a facile method to extract the carboxylated cellulose nanocrystals (CNCs) with high yield from microcrystalline cellulose (MCC) at room temperature (RT) is put forward that uses a solvent system of zinc chloride (ZnCl2) and citric acid (CA) aqueous solution. The rod-like carboxylated CNCs were achieved with a maximum yield of 72.3% and a maximum carboxyl group content of 0.75 mmol/g. Meanwhile, the crystal transformation from cellulose I to II was detected with variation of solvent composition. In addition, to the best of our knowledge, this is the first time that the iridescent phenomenon was observed in extremely thin films which were prepared from carboxylated CNC suspension with a concentration of only 0.08–0.15 wt% via evaporation-induced self-assembly. The possible formation mechanism is considered to be related to the synergistic effects of film confinement and drying stresses. Furthermore, the interaction between Petri dish substrate and the film played a role. As the first example of isolation of carboxylated CNCs with high yield at RT using ZnCl2/CA aqueous solution, this work provides a facile and practical strategy for the preparation of functional cellulose nanomaterials. [ABSTRACT FROM AUTHOR]

The increasing global concern over the contamination of natural resources, especially freshwater, has intensified the need for effective water treatment methods. This article focuses on the utilization of Cellulose nanocrystals (CNCs), sourced from lignocellulosic materials, for addressing environmental challenges. CNCs a product of cellulose-rich sources has emerged as a versatile and eco-friendly solution. CNCs boast unique chemical and physical properties that render them highly suitable for water remediation. Their nanoscale size, excellent biocompatibility, and recyclability make them stand out. Moreover, CNCs possess a substantial surface area and can be modified with functional groups to enhance their adsorption capabilities. Consequently, CNCs exhibit remarkable efficiency in removing a wide array of pollutants from wastewater, including heavy metals, pesticides, dyes, pharmaceuticals, organic micropollutants, oils, and organic solvents. This review delves into the adsorption mechanisms, surface modifications, and factors influencing CNCs' adsorption capacities. It also highlights the impressive adsorption efficiencies of CNC-based adsorbents across diverse pollutant types. Employing CNCs in water remediation offers a promising, eco-friendly solution, as they can undergo treatment without producing toxic intermediates. As research and development in this field progress, CNC-based adsorbents are expected to become even more effective and find expanded applications in combating water pollution. [ABSTRACT FROM AUTHOR]

This work reports the isolation and characterization of starch and cellulose from Commelina coelestis Willd (CCW) root. After isolation, starch and cellulose were used as a raw material to synthesize nanostructures. The yield for starch isolation from the root was 15.12% and the amylose and amylopectin contents were 26 and 74%, respectively. The starch granules had elliptical shapes and sizes ranging from 5 to 35 μm, with a crystalline B-type structure. The swelling power and solubility reached a maximum value at 85 °C, meanwhile, the water holding capacity was 29%. The bagasse had 22.9, 26.7, and 41.2% of lignin, cellulose, and hemicellulose, respectively. Starch, cellulose, starch nanocrystals (SNC), cellulose nanofibers (CNF), and cellulose nanocrystals (CNC) were studied by microscopy (SEM, AFM, TEM), XRD, and FTIR techniques. The size distribution of the SNC, CNF, and CNC ranged from 7.7 to 42.5 nm. The starch and cellulose reached temperatures above 340 °C before complete decomposition, meanwhile, CNC and CNF had lower thermal stability compared to cellulose. This study demonstrated the potential of the CCW root for the extraction of starch and cellulose, as well as the synthesis of nanomaterials derived from both biomolecules. These nanomaterials could be used to develop novel composite materials intended for packaging applications in the food industry. [ABSTRACT FROM AUTHOR]

Twisted structures are ubiquitous in plants and animals. Cellulose and chitin are natural polymers that form the structural skeleton of various twisted systems observed across different length scales, ranging from the molecular to the nano, micro, and macro scale. In addition, cellulose and chitin helicoidal structures are found to be responsible for structural coloration, enhanced mechanical properties, and motion. This review first addresses cellulose and chitin‐based chiral molecular systems and nanoscale helicoidal arrangements. Attention is given to cellulose nanocrystals, water interactions, out‐of‐equilibrium structural colorful structures formed by cellulose derivatives, and chitin's optical and mechanical properties. The discussion progresses to the micro and millimeter scales, where specific examples are presented to showcase specialized helical cellulose‐based organizations. The chosen examples illustrate the formation of different helicities, adaptative shapes, and movements at varying length scales, such as in vascular leaf petioles at the micro‐scale and millimeter‐scale in tendrils and awns of Erodium fruits. So far, the results indicate that significant work should be done on out‐of‐equilibrium systems. In addition, much must be learned from nature to produce novel twisted functional materials. This work aims to provide a comprehensive overview of the state‐of‐the‐art study of twisted cellulose and chitin‐based structures and their potential applications. [ABSTRACT FROM AUTHOR]

This work utilizes the self‐assembled cellulose nanocrystals (CNCs) as the host chiral template and fabricates a circularly polarized luminescence (CPL) film. By manipulating the photonic bandgap, the synthesized film integrates a strong CPL signal and superior mechanical flexibility. Without losing the CPL activity, the ultimate strain of 19% has exceeded most CNC‐based chiral luminescent assemblies, which enables them candidates in the optical sensor and wearable device. Meanwhile, the film has a humidity‐stimulus CPL response, with the dissymmetry factor (glum) close to 0.51. This responsive process is reversible and the optical properties can recover upon drying. Next, by manipulating the optical pathway, this work achieves on‐demand CPL direction control and meets the considerable intensity of reversed optical signals (glum: ‐0.35), avoiding the structure disruption and direction random under the external stimuli, which opens a new insight into the optical regulations. Furthermore, this work combines the in situ growth strategy and first synthesizes the dynamic‐switchable dual‐direction CPL film. Optics in both directions can be inverted simultaneously by exchanging the growth sequences. Finally, multimodal optics, excellent stability, and green manufacturing make them welcome in the advanced anti‐counterfeit areas, with the features of lossless and long‐time useful. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystal (CNC), as a typical natural photonic crystal material with outstanding advantages, has attracted increasing interests to develop stimulus‐responsive materials with vivid structural colors and circularly polarized light manipulators with high dissymmetry factors for widespread applications. However, limited by its spontaneous left‐handed cholesteric phase and absent right‐handed helical structure, current CNC‐based optical materials mainly achieve the selective reflection of left‐handed circularly polarized light (L‐CP) and the transmission of right‐handed circularly polarized light (R‐CP). Opposite to all reported intrinsic chirality in CNC assemblies, here first prominent twisted right‐handed helix in solid CNC film is found which is prepared through dynamically rotational self‐assembly. The dynamic rotation drives CNC particles to form a right‐handed helix with pitches of sub‐micron level regardless of rotary direction, realizing an ambidextrous reflection of both L‐CP and R‐CP for CNC film with maintained intrinsic structural color, and the first example of inversed right‐handed helix in CNC is further demonstrated. Moreover, the CNC films highly depend on the light propagation direction in term of apparent circular dichroism signals, presenting an exciting prospect for developing quantum transduction. This work is believed a breakthrough on chiral CNC photonic materials, providing new insights and application prospects for chiral CNC materials. [ABSTRACT FROM AUTHOR]

Polypropylene carbonate (PPC) is a biodegradable polyester with excellent toughness and ductility that may be employed as carbon fixation materials in biomedicine, agriculture, and environmental engineering. However, relatively lower strength and poor dimensional stability hinder its extensive application. In this study, nanofibrillated cellulose (NFC) and chitosan (CS) were introduced as biobased reinforcements into PPC without compromising its biodegradability. Notably, the composites not only had improved strength but also enhanced toughness after the addition of NFC and CS. The tensile strength and Young's modulus were increased by 25% and 58% in the composites with 3 wt% NFC and 2 wt% CS additions compared to pure PPC. Interestingly, the PPC/NFC/CS composites exhibited superior dimensional stability and antibacterial property. Upon the addition of 3 wt% NFC and 2 wt% CS, the composites took 3 s recovering from 0° to 137°. Additionally, NFC and CS contribute to the hydrophilicity of PPC composites. These findings offer valuable insights into experimental data and preparation techniques to the utilization of PPC in engineering fields. Highlights: The developed composites achieved maximum tensile strength (13.5 MPa).The composites with 2 wt% chitosan had effective antibacterial properties.All reinforced composites showed excellent dimensional stability.Nanofibrillated cellulose and chitosan had toughening and enhancing effect.The developed composites showed good hydrophilicity. [ABSTRACT FROM AUTHOR]

In order to contribute to the demanded sustainability transparent poly(methyl methacrylate) (PMMA) composites with cellulose nanocrystals (CNC) up to high shares of 50 wt% were prepared by in situ radical polymerization in green solvent Cyrene. The weight average molecular weights of PMMA were in the range from 144,000 to 160,000 g mol−1 and the dispersity was in the range of 1.49 to 1.89 with high conversion of monomer to polymer. The DSC thermal analysis showed that the glass transition temperature of pure PMMA was at 99°C while in composites increased from 103°C up to 129°C with the increase of CNC from 1 wt% to 50 wt%. TGA shows that the addition of CNC does not have a significant effect on the thermal stability of PMMA. In composites Young's modulus increases with the increasing CNC ratio and composites with 50 wt% of CNC showed more than twice the modulus of the PMMA matrix. The SEM images indicate uniform distribution of CNC in polymer matrix. The transparent and semitransparent PMMA/cellulose composites of improved sustainability with higher modulus of elasticity and glass transition temperature can be used as lightweight materials for a wide range of technical and everyday applications as well as optical lenses or acoustic lenses for ultrasound transducers and other devices. Highlights: Cellulose nanocrystals/PMMA composites fabricated by a green in situ process.Synthesized PMMA matrices have high molecular weights.Improved elastic modulus and glass transition temperature were achieved.Prioritizing eco‐friendly chemicals for a greener production approach. [ABSTRACT FROM AUTHOR]

Conventional colored radiative cooling (ColPRC) has a single color and limited reflection of visible light bands, which affects its radiative cooling effect, and the introduction of multiple photonic crystal structures can improve its radiative cooling performance. Therefore, in this study, a composite film was established by cross‐linking cellulose nanocrystals (CNC) with CO2‐based waterborne polyurethane (WPU) to obtain multistage structural colors. X‐ray diffraction pattern, thermogravimetric analysis, scanning electron microscopy, spectral analysis, and so on were used to examine the structure and properties of the films. The results showed that with the increase of CNC content, the color shifted blue, the crystallinity increased, the flame retardancy increased, but the thermal stability decreased; the addition of WPU assists in resisting moisture; the reflectivity of the multistage structured films is improved in the VIS–NIR range compared with the monochromatic films (an average increase of 5%), which helps to reduce solar irradiation in the visible wavelengths; high emissivity (≈90%) in the atmospheric window, which facilitates deep‐space heat exchange. The maximum temperature difference of the multistage structural color film can reach 6°C under strong solar irradiation. This research can be applied in photovoltaic devices or outdoor thermal management to provide new ways to address human energy efficiency. [ABSTRACT FROM AUTHOR]

With the implementation of the "plastic restriction order" and the demand for sustainable society development, biodegradable coatings derived from biomass materials have garnered significant interest. This study presents the synthesis of a double‐salt bio‐based waterborne polyurethane (PLA‐WPU) by utilizing poly(lactic acid) polyol (PLA) and isophorone diisocyanate (IPDI) as the main raw materials, along with 2,2‐dihydroxymethylpropionic acid (DMPA) and sodium ethylenediamine ethanesulfonate (A‐95) as a hydrophilic chain extender. Synergistic reinforcement of PLA‐WPU using hydrophobically modified cellulose nanocrystals (M‐CNC) and polycarbonate diimide (PDCDA). At an M‐CNC content of 3% relative to the effective mass of PLA‐WPU, the tensile strength reached 36.12 MPa. After 8 days a lipase PBS solution, the degradation rate reached 54%. Excellent waterproof performance was observed, exhibiting a contact angle of 143.5°. When applied as a surface coating on kraft paper, the Cobb 60 value decreased from 74.0 to 28.6 g/m2, while increasing the tensile strength by 451.3%. Importantly, the kraft paper maintained excellent waterproofing, mechanical strength, and high barrier properties even after repeated folding, high and low‐temperature conditions, and exposure to varying pH solutions. It proved to be both degradable and recyclable, making it a promising alternative to liner paper or plastic membrane, especially in food packaging. [ABSTRACT FROM AUTHOR]

Shape memory polymers (SMPs) capable of generating various deformations from anisotropic temporary shapes to permanent shapes have been emerging as soft robots. However, traditional SMPs cannot imitate the antagonistic movement of human skeletal muscles due to their modulus limitations in shape programming and recovery process. Herein, hydration programmable shape memory polymer (HP‐SMP)‐based fibers that can undergo reversible actuation by assembling antagonistic pairs are reported, where the shape programming of the antagonist muscle relies on the contraction of agonist muscle. HP‐SMP fibers are composed of tunicate cellulose nanocrystals (TCNCs) reinforced semi‐interpenetrating polymer networks. Leveraging their distinctive structure and hydration programmability, the HP‐SMP fibers exhibit large actuation strain (−60%) and high work capacity (751 J kg−1), allowing for reversible actuation under constant stress. Most significantly, the continuous antagonistic movements of HP‐SMP fibers assembled into artificial limbs are demonstrated to realize humanoid motion. This work provides new possibilities for replicating a series of lifelike human movements through the biomimetic design of antagonistic pairs of artificial muscles, utilizing renewable and sustainable biosourced materials. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop functional composite edible films or coatings for fruit preservation by the addition of bioactive components in combinations that have not yet been thoroughly studied, according to the relevant literature. Edible films were initially composed of (i) chitosan (CH), cellulose nanocrystals (CNC) and beta-cyclodextrin (CD) (50%-37.5%-12.5% ratio), and (ii) hydroxypropyl methylcellulose (HPMC), cellulose nanocrystals (CNC) and beta-cyclodextrin (CD) (50%-37.5%-12.5% ratio). The bioactive components incorporated (5, 10 and 15% v/v) were as follows: (i) pomace oil-based nanoemulsion (NE) aiming to enhance barrier properties, and (ii) caffeine (C), aiming to enhance the antioxidant activity of films, respectively. Indeed, NE addition led to very high barrier properties (low oxygen and water vapor permeability), increased flexibility and reduced color. Furthermore, the contribution of these coatings to fresh strawberries' preservation under cold storage was investigated, with very promising results concerning weight loss, color difference, and preservation of fruit moisture and quantity of O2 and CO2 inside the packages. Additionally, C addition led to very high antioxidant activity, reduced color and improved barrier properties. Finally, the contribution of these coatings to avocado's preservation under cold storage was investigated, with very encouraging results for color difference, hardness and peroxide value of the fruit samples. [ABSTRACT FROM AUTHOR]

The 3D freeze printing (3DFP) of nanocellulose aerogels are demonstrated with large‐scale aligned pore orientations as a sustainable alternative to current acoustical materials. In contrast with the unidirectional pore network orientations obtained from current 3DFP techniques, a bidirectional orientation is achieved by using an inhomogeneous printing substrate to alter the thermal gradient within the print volume. The microstructural morphology shows that bidirectional printing results in a 2D pore orientation, with comparatively thinner pore walls and larger pore widths. Acoustic measurements reveal that altering the pore network characteristics significantly affects the acoustical behavior of the printed CNC aerogels; the wider pores allow the bidirectional CNC aerogels to provide higher sound absorption performance at lower frequencies than the unidirectional samples. Notably, both 3D Freeze printed CNC aerogels provide substantially higher sound transmission loss performance as compared to current acoustical materials. The unidirectional pore structure results in CNC aerogels with higher stiffness and improved energy absorption performance, with both 3D freeze printed CNC aerogels outperforming other CNC aerogel materials in their stiffness‐to‐density ratios. The ability to simultaneously control their pore orientation and macrostructural geometry paves the way for printing complex shaped CNC aerogel structures for multifunctional noise control applications. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals are an important class of bio‐based crystalline nanostructures, finding application in several technological fields, including paper and textile coating, biocomposite engineering, biocatalysts immobilization, etc. This study explores enzymatic hydrolysis of Avicel, using endoglucanase from Aspergillus niger, to find an environmentally friendly method to extract cellulose nanocrystals from cellulose sources. Enzymatic hydrolysis has the advantage of reduced energy consumption and higher environmental friendliness compared to acid hydrolysis. In this work, we report for the first time very high nanocrystals yield by combining mechanical pretreatment of the cellulose starting material with a ball miller and endoglucanase hydrolysis, as a result of an extensive optimization of reaction conditions. In particular, a ball milling pretreatment carried out for 50 minutes at 3 Hz, allowed to isolate enzymatic CNCs with 76 % yield and with crystallinity as high as 75 %. The materials were characterized by X‐Ray diffractometry, attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, dynamic light scattering, zeta potential and field emission scanning electron microscopy (FE‐SEM). Their characteristics were compared with the properties of sulfated CNCs, prepared from Avicel by sulfuric acid hydrolysis. Our results are technologically relevant, as they contribute to the accessibility and sustainability of CNCs for a wide range of applications in various industries. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the biodegradation behaviour of starch/nanocellulose/black tea extract (SNBTE) films in a 30-day soil burial test. The SNBTE films were prepared by mixing commercial starch, nanocellulose (2, 4, and 6%), and an aqueous solution of black tea extract by a simple mixing and casting process. The chemical and morphological properties of the SNBTE films before and after biodegradation were characterized using the following analytical techniques such as field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and fourier transform infrared (FTIR). The changes in soil composition, namely pH, electrical conductivity (EC), moisture content, water holding capacity (WHC), soil respiration, total nitrogen, weight mean diameter (MDW), and geometric mean diameter (GMD), as a result of the biodegradation process, were also estimated. The results showed that the films exhibited considerable biodegradability (35–67%) within 30 days while increasing soil nutrients. The addition of black tea extract reduced the biodegradation rate due to its polyphenol content, which likely resulted in a reduction in microbial activity. The addition of nanocellulose (2–6% weight of starch) increased the tensile strength, but decreased the elongation at break of the films. These results suggest that starch nanocellulose and SNBTE films are not only biodegradable under soil conditions but also positively contribute to soil health, highlighting their potential as an environmentally friendly alternative to traditional plastic films in the packaging industry. [ABSTRACT FROM AUTHOR]

This work aims to recycle peanut shells (residues) to use them as raw materials to produce nanocrystal cellulose. Two methods were used to synthesis zinc oxide nanoparticles (ZnO NPs) on cellulose nanocrystals (CNCs), in order to form the cellulose/zinc oxide nanoparticles (CNC/ZnO NPs). According to the results, Fourier transform infrared, X-ray diffraction, UV–visible, scanning electron microscopy, and energy-dispersive X-ray analysis characterized the CNC/ZnO NPs. UV-Visble spectra showed maximum absorption at 366 nm related to the zinc oxide. Fourier transform infrared spectra exhibit a weak peak at 432 cm−1 attributed to zinc oxide vibration, confirming the formation of zinc oxide nanoparticles on cellulose nanocrystals. X-ray diffraction confirmed the crystalline nature of cellulose/zinc oxide nanoparticles with an average size between 20 and 28 nm. Scanning electron microscopy survey shows that the obtained nanoparticles have a lattice shape of rods surrounded by zinc oxide nanoparticles with a hexagonal wurtzite structure, as established by energy-dispersive X-ray analysis to confirm the presence of carbon, zinc, and oxygen. These cellulose/zinc oxide nanoparticles were tested against human pathogenic bacteria (Escherichia coli ATCC25922, Klebsiella pneumoniae ATCC 10,031, Staphylococcus aureus ATCC 25,923) and a fungus (Candida albicans ATCC 14,053). The obtained results revealed that these cellulose/zinc oxide nanoparticles synthesized from peanut shells have the effectiveness of an antibacterial activity against Gram (+) and Gram (−) bacteria together, and it shows excellent antifungal activity against Candida albicans; it seems to have an immense potential as the source of antibacterial and antifungal compounds. These results indicate that these newly fabricated cellulose/zinc oxide nanoparticle bio-nanocomposites by both methods contain potential antimicrobial components that may be of great benefit in the development of antimicrobial pharmaceutical industries and can be used as a treatment against various diseases caused by these organisms. It can also be employed in food systems as a novel preservative to inhibit microbial growth and repress the synthesis of exotoxins or control the growth of spoilage and disease-causing microorganisms. [ABSTRACT FROM AUTHOR]

The global water crisis demands immediate attention, and atmospheric water harvesting (AWH) provides a viable alternative. However, studying the real‐time subtle relationship between water absorption, diffusion, and internal structure for hygroscopic materials is challenging. Herein, a dynamic visualization technique is proposed that utilizes an in situ electrical impedance tomography (EIT) system and a precise reconstruction algorithm to achieve real‐time monitoring of the water sorption process within aerogels from an internal microstructural perspective. These results can be inferred that composites' pore sizes affecting the kinetics of their moisture absorption. In addition, the diffusion path of moisture absorption and the distribution of stored moisture inside aerogels exhibit intrinsic self‐selective behavior, where the fiber skeleton of the aerogel plays a crucial role. In summary, this work proposes a generic EIT‐based technique for the in situ and dynamic monitoring of the hygroscopic process, pointing to an entirely new approach regarding research on AWH materials. [ABSTRACT FROM AUTHOR]

The exceptional benefits of structural defects and doped atoms in carbon network regarding electromagnetic properties inspire the design of advanced carbon‐based microwave absorption (MA) materials. However, excessive structural defects decline the physical properties of materials, especially their conductivity. Therefore, it is a great challenge to balance structural defects and doped atoms to optimize conductive behavior for carbon‐based MA materials. The spiral carbon nanocoil (CNC), with coexisting amorphous and polycrystalline carbon structures and moderate conductivity, has significant MA properties but lacks pores and doped atoms. Herein, the amorphous carbon parts with relatively weak C─C bond energies are preferentially oxidized at 500 °C in air atmosphere to create pores and combine O atoms in the bodies of CNCs. Furthermore, the mechanism prioritizing the formation of O doping over defects is discovered. Benefiting from the synergistic interplay of structural defects and O dopants, the O‐enriched porous CNCs demonstrate enhanced conduction and polarization losses than the pure CNCs, realizing a wide effective absorption bandwidth of 7.3 GHz at a filling ratio of only 3 wt.%. Theoretical calculations further support these experimental results. The combination of structural defects and doped atoms may serve as an effective pathway for unlocking tunable dielectric properties of carbon‐based materials. [ABSTRACT FROM AUTHOR]

Nowadays, the development of sustainable materials using chemical routes that are less harmful to the environment, adding social and economic viability to developed countries is a significant challenge. In this context, the present study extracted cellulose nanocrystals (CNC) based on two different chemical routes (H2SO4 and H2SO4/HCl) using a sub-wear out fiber from a natural resource in the semiarid Brazilian region with proposal of social and economically promoting this area and produce low-cost CNC. The two CNC (CNC H2SO4 and CNC H2SO4/HCl) were extensively characterized by spectroscopic analysis (FTIR, XPS, UV-Vis), X-ray diffraction, and morphological analysis (SEM, TEM). In addition, morphological analysis was performed after heat treatment to analyze the dependence on the thermodynamic kinetic in nucleation and growth of nanocrystals. The CNC biocompatibility was tested using a Resazurin assay. The results showed differences in morphologies, crystalline structures and chemical groups in the CNC depending on the chemical route. The sizes of CNC H2SO4 and H2SO4/HCl were 30 and 50 nm, respectively. The cytotoxicity studies were statistically similar showing biocompatibility (approximately 90%). Thus, these results indicated the potential to the possibility to improve social and economic conditions in the semiarid Brazilian region using a sub-wear-out waste as source producing a final product with aggregate value to the market. [ABSTRACT FROM AUTHOR]

Highlights Currently, toughening poly(lactic acid) (PLA) without reducing its strength and modulus is still challenging. Fortunately, this problem could be addressed by incorporating cellulose nanocrystals grafted with epoxidized soybean oil (CNCs‐g‐ESO) into the PLA matrix. The percolation threshold for uniform dispersion of the CNCs‐g‐ESO in the PLA matrix was about 0.8 wt%. The loading made the elongation at break and tensile fracture energy of the PLA composite film increase to 26.5 and 11.26 from 3.7% and 0.96 MJ.m−3, respectively, concerning the neat PLA. Meanwhile, it also resulted in a 4.7% and 12.4% increase in the tensile strength and Young's modulus, respectively. Additionally, the initial decomposition temperature (T5%) of the PLA composite increased to 334.9 from 316.1°C after incorporating the CNCs‐g‐ESO. Therefore, the CNCs‐g‐ESO, acting as an ESO‐like plasticizer and a CNCs‐like nucleating agent, is a potential nanofiller for reinforcing and toughening PLA. Cellulose nanocrystal grafted with epoxidized soybean oil (CNCs‐g‐ESO) The CNCs‐g‐ESO acting as both plasticizer and nucleating agent The CNCs‐g‐ESO decreasing the spherulite size, but increasing the CrI of PLA The CNCs‐g‐ESO enlarging the window for thermal process of PLA Simultaneous reinforcement and toughness of PLA [ABSTRACT FROM AUTHOR]

In the present study, a multilayer, high-barrier, thin blown film based on a polybutylene adipate terephthalate (PBAT) blend with polyhydroxyalkanoate (PHA), and composed of four layers including a cellulose nanocrystal (CNC) barrier layer and an electrospun poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) hot-tack layer, was characterized in terms of the surface roughness, surface tension, migration, mechanical and peel performance, barrier properties, and disintegration rate. The results showed that the film exhibited a smooth surface. The overall migration tests showed that the material is suitable to be used as a food contact layer. The addition of the CNC interlayer had a significant effect on the mechanical properties of the system, drastically reducing the elongation at break and, thus, the flexibility of the material. The film containing CNCs and electrospun PHBV hot-tack interlayers exhibited firm but not strong adhesion. However, the multilayer was a good barrier to water vapor (2.4 ± 0.1 × 10−12 kg·m−2·s−1·Pa−1), and especially to oxygen (0.5 ± 0.3 × 10−15 m3·m−2·s−1·Pa−1), the permeance of which was reduced by up to 90% when the CNC layer was added. The multilayer system disintegrated completely in 60 days. All in all, the multilayer system developed resulted in a fully compostable structure with significant potential for use in high-barrier food packaging applications. [ABSTRACT FROM AUTHOR]

The combination of cellulose nanocrystals (CNCs) with synthetic polymers like polypropylene (PP) offers the opportunity to create advanced nanocomposites with significant advantages in terms of mechanical properties, improved thermal stability, enhanced barrier properties, and sustainability. However, a major drawback for incorporation of CNCs in polymer matrices is their poor dispersion and incompatibility with industrial processing of many composites. This work aims to improve the dispersion of hydrophilic CNCs in a hydrophobic matrix using a method which could be adapted for the industrial level. CNCs are extracted from Ampelodesmos mauritanicus (El Diss plant) (CNCD) and incorporated in a polypropylene matrix using the masterbatch method. A first nanocomposite (PP/CNC-Gr) was prepared by adding maleic anhydride (MA) to a CNCD/PP suspension, while the second nanocomposite (PP/CNC-Co) was achieved by using a MA-grafted PP (PP-g-MA) as a third component. Concentrated masterbatch underwent solution casting followed by homogenization in a Brabender mixer. Mechanical properties comparison showed that PP/CNC-Co nanocomposites exhibited greater resistance relatively to PP/CNC-Gr nanocomposites. Moreover, PP/CNC-Co nanocomposites revealed an improved thermal stability and a higher complex viscosity, particularly with 3% of CNCD. Properties enhancements are attributed to the reaction between MA groups grafted to PP chains and hydroxyl groups of CNCDs, which enables an improved interfacial adhesion, leading to more continuous materials, as perceived from the increase in viscosity and morphology observation. On the other hand, MA reaction with PP chains and CNCD induced only a partial coverage of CNCDs during nanocrystals treatment, conferring relatively lower properties to PP/CNC-Gr nanocomposites. [ABSTRACT FROM AUTHOR]

Nanocellulose (NC)/graphene oxide (GO) composites are attractive materials with a range of unique features obtained from the integration of NC and GO. These materials have high potential use in various sectors such as biomedicine, wastewater remediation, sensor/biosensor technology, and energy storage/conversion. The simple functionalization and modification of NC or GO afford an opportunity for tailoring these materials for anticipated applications. In wastewater treatment applications, they can be employed as reliable adsorbents for the removal of different pollutants, such as metals, dyes, oils, and pesticides as well as sensors for the detection and monitoring of these pollutants. Besides that, NC/GO composites can be applied as catalysts for catalytic degradation for a wide variety of pollutants. These materials have been also reported to be applicable in biomedical applications such as drug delivery, antibacterial and biosensing. Energy storage applications such as supercapacitors NC/GO-based materials were also utilized. This review summarizes NC/GO hybrid fabrication, characterization, and their application in different fields, i.e. sensing, energy storage, and wastewater remediation. It also covered a broad overview of the status of integrating GO with nanocellulose materials, i.e. bacterial cellulose, cellulose nanofibrils, and cellulose nanocrystals. We concluded with the challenges and outlook for NC/GO-based composites. [ABSTRACT FROM AUTHOR]

The use of fillers based on natural resources in composite materials represents a massive potential for biomedical applications. However, up to this date, the use of natural resources for materials reinforcement in dental field is still lacking. Thus, the suitability of using kenaf cellulose nanocrystals as a co-filler treated via silane hybridization was assessed by means of thermal stability and mechanical strength of rice husk nanohybrid dental composite. Kenaf cellulose nanocrystals (CNCs) were surface-modified and treated with silane hybridization at varying ratios of γ-methacryloxypropyltrimethoxysilane and tetraethyl orthosilicate sol–gel (0:1, 1:1, 1:2, and 1:3). Following chemical and thermal analysis, the treated kenaf CNCs were incorporated into the nanohybrid rice husk dental composites (K00, K01, K11, K12, and K13). The prepared samples were sent for flexural and compressive strength tests. The Fourier transform infrared spectroscopy spectra detected the formation of chemical bonds between kenaf CNCs and γ-MPS/TEOS hybridized silane. For thermogravimetric analysis, the untreated kenaf CNCs recorded the highest decomposition temperature compared to silane-treated kenaf CNCs. The K13 composite (silane-treated kenaf CNCs with γ-MPS:TEOS of 1:3) demonstrated an enhanced flexural strength of 31% and compressive strength of 38% compared to the non-fiber-reinforced composite. In conclusion, optimal surface treatment hybridization of kenaf CNCs with silane at γ-MPS:TEOS of 1:3 significantly enhanced the mechanical properties of the rice husk nanohybrid dental composite and insignificantly influenced the thermal stability of the composite. [ABSTRACT FROM AUTHOR]

This study systematically investigates the flow birefringence of cellulose nanocrystal (CNC) suspensions. The aim is to clarify the importance of the stress component along the camera's optical axis in the stress-optic law (SOL), which describes the relationship between birefringence, the retardation of transmitted polarized light, and the stress field. More than 100 datasets pertaining to the retardation of CNC suspensions (concentrations of 0.1, 0.3, 0.5, and 1.0 wt%) in a laminar flow field within a rectangular channel (aspect ratios of 0.1, 1, and 3) are systematically obtained. The measured retardation data are compared with the predictions given by the conventional SOL excluding the stress component along the camera's optical axis and by the SOL including these components as second-order terms (2nd-order SOL). The results show that the 2nd-order SOL gives a significantly better agreement with the measurements. Based on the 2nd-order SOL, the retardation at the center of the channel, where the effect of the stress component along the camera's optical axis is most pronounced, is predicted to be proportional to the square of the flow rate, which agrees with the experimental data. The results confirm the importance of considering the stress component along the camera's optical axis in the flow birefringence of CNC suspensions at high flow rates, even for quasi-two-dimensional channel flow. [ABSTRACT FROM AUTHOR]

The broad applications of cellulose nanocrystal (CNC) films are restricted by their low resistance against water and brittleness. In this study, high barrier transparent films composed of CNCs and maltitol, used as a bio-plasticizer (at up to 30% weight), were prepared by spray deposition. Addition of plasticizer increased the optical transmittance of the films. It also improved elongation at break and flexibility of the films, while reducing Young's modulus and tensile strength. The barrier properties of CNC films plasticized with maltitol were significantly improved over CNC. In particular, films containing 30 wt.% maltitol showed a water vapor permeability of 3.67 × 10–12 (g/Pa.s.m) and oxygen permeability of 4.75 (cm3.µm/m2.day.Pa) corresponding to 94% and 78% reductions over CNC films, respectively. This remarkable barrier improvement is attributed to a combination of decreased porosity and the interaction of hydroxy groups of maltitol and CNCs. This interaction led to a reduction of the free hydroxy groups available to interact with the water molecules diffusing in the nanocomposite films, as confirmed by dynamic vapor sorption measurements. This study presents maltitol as a green plasticizer significantly improving the CNC film properties and enabling new barrier applications. [ABSTRACT FROM AUTHOR]

To realize high value recovery of waste cotton fabric, cellulose nanocrystals (CNCs) were prepared from waste cotton fabric by sulfuric acid hydrolysis, and the prepared CNCs were analyzed from morphology, size and physicochemical property by various characterization methods. The enhancement effect of CNCs on mechanical property of PVA films were explored. The results showed that the prepared CNCs presented a short rod-like structure, with length 168 nm±71 nm and diameter 19 nm±11 nm, and the yield was 54. 2%. The Zeta potential value of CNCs was -31. 8 mV and its dispersion stability was better, the thermal stability of CNCs showed a decrease compared to cotton fabric. The CNCs remained cellulose type I structure with crystallinity of 80.8%. When the mass fraction of CNCs was 5%, compared with PVA film, the tensile strength and breaking elongation rate of PVA composite film were increased 37.8% and 32.7% respectively. It is considered that properties of the prepared CNCs from waste cotton fabric by sulfuric acid hydrolysis are excellent, the mechanical properties of PVA composite film are significantly reinforced, which widen the way of recycling utilization of waste cotton fabric. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs) are commercially available materials derived from cellulose, the most abundant biopolymer on our planet. Due largely to their high strength, high surface area‐to‐volume ratio, tailorable surface chemistry, and the abundance of biomass feedstocks with which to produce them, CNCs have attracted significant interest in applications spanning the paints and coatings, composites, packaging, and biomedical sectors. However, and perhaps most interestingly, CNCs will self‐assemble (or, as I've teased in the title, organize) to form highly ordered chiral nematic liquid crystal phases when concentrated in suspension. Upon complete solvent evaporation, this chiral nematic order is 'locked', yielding films with structural colour—colour arising not due to chemical pigments, but rather due to the physical structure of a material itself. In the pursuit of novel multi‐functional materials, research interest has shifted recently towards the incorporation of functional additives to form composite chiral nematic films. Along with introducing the basics of liquid crystals and self‐assembly, this review discusses the main approaches used in order to form CNC‐based composite films: co‐assembly, templating, and post‐processing, and highlights exceptional examples in each case. Finally, I give my uniquely Canadian perspective on the current status, future prospects, and major challenges associated with the development of CNC‐based chiral nematic composite materials. [ABSTRACT FROM AUTHOR]

The application of hydrogels in the field of wearable flexible sensors has been widely discussed. However, most hydrogels have certain limitations in their mechanical properties, stability and self-recovery, which greatly limits their application in flexible sensors. In this paper, carbon nanotube composite hydrogels with good stability and high tensile properties were prepared by using acrylamide (AM), cellulose nanocrystals (CNC) and multi-walled carbon nanotubes (MWCNTs) as raw materials in water/glycerol by using a one-pot method. The composite hydrogels were characterized by using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy, and their mechanical properties, conductivity and stability were tested. The results show that the composite hydrogel has a higher elongation at break (596.02%) and a higher tensile strength (0.26 MPa) when the content of cellulose nanocrystals (CNC) is 1 wt%. This is due to the presence of hydrogen bonds and the electrical conductivity of the composite hydrogels can be improved by adding carbon nanotubes (MWCNTs). When 0.06 g carbon nanotubes (MWCNTs) were added, the conductivity of the composite hydrogel reached 0.244 S m−1, showing good conductivity. In addition, the wearable flexible sensor based on the composite hydrogel had a measurement coefficient of 7.20 (400% strain), and the response time and recovery time of the hydrogel were both 150 ms, which is a short response time and can detect human movement. In addition, flexible sensors based on hydrogels can successfully detect finger and wrist movement changes and show good stability. Therefore, carbon nanotube composite hydrogels with good stability and high tensile properties have broad application prospects in the field of wearable flexible sensors. [ABSTRACT FROM AUTHOR]

Understanding the percolation threshold is essential for determining the performance of particle‐reinforced polymer composites. Spray‐dried cellulose nanocrystals (SDCNC) of micrometer size reinforced homopolymer polypropylene (HPP) composites at 20, 30, 40, and 50 wt.% were prepared to investigate the percolation threshold of SDCNC particles in HPP. The effect of a compatibilizer (maleic anhydride polypropylene (MAPP)) at 3, 5, and 7 wt.%, on the SDCNC percolation networks and composites performance were also studied. The results indicated that SDCNC particle percolation networks in HPP were established between 30 and40 wt.%. For composites without MAPP, the impact strength significantly increased by up to 23% below the percolation threshold and declined beyond it. The peak crystallization temperature of HPP was steadily increased until 30 wt.% SDCNC particles were added due to the SDCNC saturated nucleation function at the threshold. Introducing MAPP significantly improved tensile strength (58%), tensile strain (61%), flexural strength (45%), and impact strength (91%) compared with the corresponding composites without MAPP, attributed to the enhanced interfacial adhesion between the SDCNC particles and HPP. Water absorption results indicated that adding MAPP changed the SDCNC particle distribution networks within the matrix above the percolation threshold but did not change it below the threshold. [ABSTRACT FROM AUTHOR]

A bio‐based nanocomposite optical film was obtained through a simple sol‐gel process and solution casting. The dispersion effect of cellulose nanocrystals (CNCs) gel and the optical properties, mechanical performance and thermal stability of CNC‐doped cellulose triacetate (TAC) films (TAC−X) were systematically evaluated. The results show that CNCs can be well dispersed in hydrophobic organic solvents and TAC matrices through the sol‐gel process. TAC−X film has excellent optical properties, its light transmittance is above 92 %, its haze value and birefringence are low, ranging from 0.21±0.01 % to 0.38±0.02 %, and (1.64±0.26)×10−6 to (2.49±0.50)×10−6 respectively. When doped with 2 wt % CNCs, the tensile strength and Young's modulus of the TAC‐2 film were 33.0 % and 30.1 % higher than those of the pure TAC film, separately. At the same time, the TAC−X film also maintains good thermal stability, with its glass transition temperature and maximum decomposition temperature falling between 215–216 °C and 366–368 °C respectively. The simple sol‐gel process provides a convenient and efficient way to use CNCs doping to enhance the physical and mechanical properties of TAC optical films. [ABSTRACT FROM AUTHOR]

Integrating photonic crystals (PCs) into the design of a photocatalyst can significantly enhance its light‐harvesting capability. PCs can manipulate the propagation of light uniquely within a material and reduce its group velocity, thereby enhancing the absorption factor for photocatalysts. However, the slow photon effect in photoactive films with chiral nematic structures has not been reported yet, especially at the blue edge of the photonic bandgap. This work proposes a straightforward one‐pot method to fabricate various photonic films with chiral nematic, namely g‐C3N4/SiO2, TiO2/SiO2, and g‐C3N4/TiO2/SiO2. The sol‐gel biotemplating formulation using cellulose nanocrystals successfully leads to the elaboration of films exhibiting variable iridescent colors with photonic bandgap from UV to visible range. The tunable wavelength of the Bragg peak reflection offers the opportunity to access a region with a slow photonic effect, which directly impacts the light‐harvesting properties of the photoactive material. It is demonstrated that the H2 generation is significantly enhanced when the blue edge of the photonic bandgap position overlapped with the absorbance band of the photocatalyst. These results offer the opportunity to design photonic materials with chiral nematic structure and optimize the photocatalytic performance for energy application. [ABSTRACT FROM AUTHOR]

Polyethylene glycol (PEG) / Cellulose nanocrystal (CNC) structural colored films with good flexibility and humidity sensitive were prepared by using the evaporation-induced self-assembly method. The influence of PEG's molecular weight and content on the change of structural color, toughening and humidity-sensitive of CNC films were systematically investigated through optical properties, morphologies, mechanical properties, and humidity responsiveness. Optical measurement results showed that the structural color and the maximum reflected light wavelength (λmax) of CNC films were red-shifted by adding PEG. The higher the PEG molecular weight and content, the more obvious the red-shift was. Morphology characterization demonstrated the red-shift was attributed to the increasing pitch of the chiral nematic phase structure. Mechanical results showed that adding PEG significantly improved the toughness of CNC films, the higher the PEG molecular weight and content, the higher toughening effect. The toughness enhancement can be attributed to PEG being soft and having good interaction with CNCs, can be regarded as an energy dissipating binding phase which increased the energy dissipation during CNCs movement. Humidity responsiveness showed that the humidity sensitivity of CNC film was improved with PEG concentration increasing, but was independence of PEG molecular weight. Furthermore, the rheological behavior and thixotropy recovery were studied to explain the influence of PEG on the self-assembly behavior of CNCs in suspension. This study provides a foundation for regulation of CNC structural colored films with good toughness and humidity-sensitive. [ABSTRACT FROM AUTHOR]

The demand for thermally insulating, ultraviolet (UV) shielding materials derived from natural resources to meet sustainable societal development is of utmost importance due to increased energy consumption and environmental concerns. Cellulose nanocrystals (CNCs) are currently regarded as one of the most intriguing green nanomaterials with tremendous application potential, owing to their availability, renewability, biodegradability and intrinsic biocompatibility. This work presents an efficient approach for the eco-friendly utilization of wastepaper (WP) through the extraction of CNCs from it. Also, the practical applicability of CNCs is explored through the investigation of thermal properties such as thermal diffusivity and thermal conductivity via a dual-beam mode mismatched thermal lensing (TL). The thermal diffusivity values of the dispersion of CNCs in water and ethanol are found to be 5.741 × 10–8 to 4.271 × 10–8 m2s−1 and 7.909 × 10–8 to 5.507 × 10–8 m2s−1, respectively. The results of the current study are expected to pave a new path for the development of forthcoming thermal insulation materials derived from environmentally benign and sustainable CNCs. [ABSTRACT FROM AUTHOR]

The present study discusses the effect of symmetric and asymmetric grafting on the surface of CNCs (cellulose nanocrystals) on their dispersion properties using dialkyl azetidinium salts. Three dialkylamine of different size and chain length were successfully grafted to the sulfate groups on the surface of CNCs by conjugation of azetidinium salts. The coupling process resulted in the formation of 2-hydroxypropyl-N-dialkylamine conjugated to the CNC sulfate groups abbreviated as C n -N-C m -Prop-2-OH-CNC, where m, n are the number of carbons in the alkyl groups, each with a total of m + n = 12 , with (m , n) = (11 , 1) ; (9 , 3) ; (6 , 6) . Molecular dynamics simulations were used to assess the probable morphology of the grafted chains and the interaction potential between CNCs. Steady shear simultaneously combined with polarized light imaging and oscillatory shear rheological measurements were used to evaluate for the first time the impact of the CNC surface modifications on their dispersion flow and optical properties. Overall, the results show that the different linker topologies could effectively promote different types of aggregation morphologies based on the size of the linker, their flexibility and their most probable conformation. [ABSTRACT FROM AUTHOR]

Adhesives are widely used in daily life. However, during their preparation or application, traditional adhesives easily release toxic gases, which adversely affect the human body and the environment. Herein, a physically crosslinked tannic acid (TA)-based adhesive is prepared by forming hydrogen bonding between cellulose nanocrystals (CNCs), polyacrylamide (PAM), and TA. Different characteristics of the prepared adhesives, including morphology, water content, biocompatibility, curing time, and adhesion properties, were investigated. Lap shear strength of the adhesive depends on the water content and curing time, reaching a maximum at a curing time of 48 h. The addition of CNCs enhances the lap shear strength, with the adhesive sample with 6.0 g CNCs exhibiting a high lap shear strength of 5.5 MPa on wood, which is 34% higher than that of the PAM/TA adhesive. Moreover, TA-based adhesives have excellent biocompatibility. These CNC/PAM/TA adhesives have excellent potential for application in the furniture, construction, and building industries. [ABSTRACT FROM AUTHOR]