Amidation of carboxy groups in TEMPO-oxidized cellulose for improving surface hydrophobization and thermal stability of TEMPO-CNCs.

Surface-hydrophobized cellulose nanomaterials (CNs) with high thermal degradation points are required for preparing various materials, such as epoxy nanocomposites, which possess high mechanical strength, optical transparency, and thermal stability. Amidation of carboxy groups in CNs is one possible chemical modification for hydrophilic CNs that contain abundant carboxy groups. However, achieving efficient amidation of high ratios of carboxy groups in CNs is highly challenging for industrial applications. In this study, carboxy group-containing fibrous wood pulp was subjected to amidation in heterogeneous solid/liquid systems to prepare products with high amidation ratios and high yields, while implementing cost-effective isolation and purification processes. Consequently, a partially acid-hydrolyzed wood pulp with abundant carboxy groups was first prepared. Subsequently, 88 % and 91 % of the carboxy groups in the pulp were successfully amidated using polyalkylene glycols-NH2 and octylamine, respectively. This was achieved by utilizing 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride and N-methylmorpholine as the condensation reagent and activator, respectively, in N,N-dimethylformamide (DMF) at approximately 23 °C for 16 h. The thermal degradation point increased from 224 °C for the acid-hydrolyzed pulp to over 250 °C after amidation. The amidated pulps were then converted into transparent dispersions, consisting of amidated cellulose nanocrystals, by homogenization in an epoxy monomer/DMF mixture using high-pressure homogenization.

Fabrication of stereocomplex-type poly(lactic acid) nanocomposites based on the selective nucleation of poly(vinyl acetate) modified cellulose nanocrystals.

The incorporation of biomass fillers into poly(lactic acid) (PLA) enantiomeric blends offers a novel strategy to promote stereocomplex (SC) crystallization while preserving the biodegradability of PLA. In this study, poly(vinyl acetate)-modified cellulose nanocrystals (CNC-PVAc) were prepared through a one-pot reaction and employed as nanofillers for PLA. The results indicate that CNC-PVAc enhances the crystallization of stereocomplex crystallites (SCs) while inhibiting the formation of homocrystallites (HCs). The selective nucleation induced by CNC-PVAc is closely associated with the enrichment of PVAc chains at the interface between CNCs and the PLA matrix. Due to the good miscibility between PVAc and PLA, PVAc enhances chain segment motility and suppresses the homocrystallization of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA), thereby facilitating the pairing and crystallization of PLA enantiomers into SCs. Furthermore, the nucleation and reinforcing effects of CNC-PVAc play a synergistic role in determining the properties of PLA based nanocomposites. The fabricated nanocomposites exhibit significant improvements in yield strength, Young's modulus, and heat distortion resistance, while maintaining the original biocompatibility and degradability of PLA. Overall, this study elucidates the nucleation mechanism of polymer-grafted CNCs on PLA SCs, and expanding the application potential of biobased fillers in biodegradable polymers.

Wetting and emulsification properties of cellulose nanocrystals modified with tannic acid and alkyl cellulose derivatives.

HYPOTHESIS: Cellulose nanocrystals (CNCs) are sustainable rod-like nanoparticles that can be used to stabilize oil-in-water emulsions and can create hydrophilic coatings. Modifying the surface of CNCs can improve emulsion properties and allow for adjustable wettability. EXPERIMENTS: This study explores the improvement of Pickering emulsion properties for various oils and the adjustability of coated surfaces through the physical modification of CNCs, without chemical functionalization. Bio-based additives, including antioxidant tannic acid (TA), methyl cellulose (MC), and ethyl cellulose (EC) were used as surface modifiers. The identification of optimal formulations involved varying the weight fraction of the alkyl cellulose derivatives. FINDINGS: The findings suggest that, akin to pure CNCs, Pickering emulsions stabilized by TA and/or MC-modified CNCs demonstrate comparably high stability. The introduction of MC at a low weight fraction enhances hydrophilicity, and AFM analysis reveals smooth surfaces, mitigating the potential influence of roughness. In contrast, EC-modified CNCs result in less stable emulsions but exhibit more hydrophobic surfaces. This translates to a broad spectrum of characteristics, ranging from quasi-superhydrophilic to nearly hydrophobic (with contact angles spanning from below 11° up to 68°), all controllable through a straightforward physical coating process. This facile preparation of coated CNCs provides a versatile approach to customizing the wetting and emulsification properties of nanomaterials.

Submillisecond Electric Field Sensing with an Individual Rare-Earth Doped Ferroelectric Nanocrystal.

Understanding the dynamics of electrical signals within neuronal assemblies is crucial to unraveling complex brain functions. Despite recent advances in employing optically active nanostructures in transmembrane potential sensing, there remains room for improvement in terms of response time and sensitivity. Here, we report the development of such a nanosensor capable of detecting electric fields with a submillisecond response time at the single-particle level. We achieve this by using ferroelectric nanocrystals doped with rare-earth ions that produce upconversion (UC). When such a nanocrystal experiences a variation of surrounding electric potential, its surface charge density changes, inducing electric polarization modifications that vary, via a converse piezoelectric effect, the crystal field around the ions. The latter variation is finally converted into UC spectral changes, enabling optical detection of the electric potential. To develop such a sensor, we synthesized erbium and ytterbium-doped barium titanate crystals of ≈160 nm in size. We observed distinct changes in the UC spectrum when individual nanocrystals were subjected to an external field via a conductive atomic force microscope tip, with a response time of 100 µs. Furthermore, our sensor exhibits a remarkable sensitivity of 4.8 kV/cm/Hz, enabling time-resolved detection of a fast-changing electric field of amplitude comparable to that generated during a neuron action potential.

Multitwinned Ice Nanocrystals.

Multitwinned nanocrystals are commonly found in substances that preferentially adopt tetrahedral local arrangements, but not yet in water crystals. Ice nanocrystals are pivotal in cloud microphysics, and their surfaces become increasingly prominent in determining structure as crystal size decreases. Nevertheless, discussions on nanocrystal structures have predominantly centered on ice polymorphs observed in bulk: hexagonal (Ih), cubic (Ic), and stacking-disordered (Isd) ices. Here, we demonstrate, through molecular dynamics (MD) simulations, that decahedral and icosahedral nanocrystals form from liquid water droplets of a few nanometers in size without violating the ice rule. The brute force spontaneous crystallization is conducted using the mW model, and the thermodynamic stability is examined using the TIP4P/Ice model. During the crystallization process, the formation of twin boundaries precedes the emergence of centers exhibiting 5-fold and icosahedral symmetry. The free energy calculation suggests the icosahedron has comparable stability with ice Ih nanocrystal. The frequent occurrence of these unreported ice nanocrystals aligns with the fact that natural polycrystalline snow crystals predominantly display a 70.5-degree angle between the Ih c-axes of adjacent branches. Moreover, we show that the formation of multitwinned ice nanocrystals is enhanced within a fullerene, providing a potential avenue for experimental observations.

Mechanical Performance of Cellulose Nanocrystal and Bioceramic-Based Composites for Surgical Training.

This study evaluated the mechanical performance of a cellulose nanocrystal (CNC)-based composite, consisting of hydroxyapatite and natural fibers, mimicking the mechanical properties of real bone. The effect of natural nanofibers on the cutting force of the composite was evaluated for suitability in surgical training. Although hydroxyapatite has been extensively studied in bone-related applications, the exploration of epoxy-based composites incorporating both hydroxyapatite and CNC represents a novel approach. The evaluation involved a load cell with an oscillating saw. The uniform distribution of CNCs within the composite was assessed using 3D X-ray imaging. The cutting force was found to be 4.005 ± 0.5469 N at a feed rate of 0.5 mm/s, comparable to that required when cutting real bone with the osteon at 90°. The 90-degree orientation of the osteon aligns with the cutting direction of the oscillating saw when performing knee replacements on the tibia and femur bones. The addition of CNCs resulted in changes in fracture toughness, leading to increased material fragmentation and surface irregularities. Furthermore, the change in the cutting force with depth was similar to that of real bone. The developed composite material enables bone-cutting surgeries using bioceramics and natural fibers without the risks associated with cadavers or synthetic fibers. Mold-based computed tomography data allows for the creation of various bone forms, enhancing skill development for surgeons.

Crosslinkable Ligands for High-Density Photo-Patterning of Perovskite Nanocrystals.

Perovskite nanocrystals (PNCs) are promising luminescent materials for electronic color displays due to their high luminescence efficiency, widely-tunable emission wavelengths, and narrow emission linewidth. Their application in emerging display technologies necessitates precise micron-scale patterning while maintaining good optical performance. Although photolithography is a well-established micro-patterning technique in the industry, conventional processes are incompatible with PNCs as the use of polar solvents can damage the ionic PNCs, causing severe luminescence quenching. Here, we report the rational design and synthesis of a new bidentate photo-crosslinkable ligand for the direct photo-patterning of PNCs. Each ligand contains two photosensitive acrylate groups and two carboxylate groups, and is introduced to the PNCs via an entropy-driven ligand exchange process. In a close-packed thin film, the acrylate ligands photo-polymerize and crosslink under ultraviolet light, rendering the PNCs insoluble in developing solvents. A high-density crosslinked PNC film with an optical density of 1.1 is attained at 1.4 µm thickness, surpassing industry requirements on the absorption coefficient. Micron-scale patterning is further demonstrated using direct laser writing, producing well-defined 20 µm features. This study thus offers an effective and versatile approach for micro-patterning PNCs, and may also be broadly applicable to other nanomaterial systems.

Efficient Isolation of Cellulose Nanocrystals from Seaweed Waste via a Radiation Process and Their Conversion to Porous Nanocarbon for Energy Storage System.

This article presents an efficient method for isolating cellulose nanocrystals (CNcs) from seaweed waste using a combination of electron beam (E-beam) irradiation and acid hydrolysis. This approach not only reduces the chemical consumption and processing time, but also improves the crystallinity and yield of the CNcs. The isolated CNcs were then thermally annealed at 800 and 1000 °C to produce porous nanocarbon materials, which were characterized using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy to assess their structural and chemical properties. Electrochemical testing of electrical double-layer capacitors demonstrated that nanocarbon materials derived from seaweed waste-derived CNcs annealed at 1000 exhibited superior capacitance and stability. This performance is attributed to the formation of a highly ordered graphitic structure with a mesoporous architecture, which facilitates efficient ion transport and enhanced electrolyte accessibility. These findings underscore the potential of seaweed waste-derived nanocarbon as a sustainable and high-performance material for energy storage applications, offering a promising alternative to conventional carbon sources.

Integrating an antimicrobial nanocomposite to bioactive electrospun fibers for improved wound dressing materials.

This study investigates the fabrication and characterization of electrospun poly (ε-caprolactone)/poly (vinyl pyrrolidone) (PCL/PVP) fibers integrated with a nanocomposite of chitosan, silver nanocrystals, and graphene oxide (ChAgG), aimed at developing advanced wound dressing materials. The ChAgG nanocomposite, recognized for its antimicrobial and biocompatible properties, was incorporated into PCL/PVP fibers through electrospinning techniques. We assessed the resultant fibers' morphological, physicochemical, and mechanical properties, which exhibited significant enhancements in mechanical strength and demonstrated effective antimicrobial activity against common bacterial pathogens. The findings suggest that the PCL/PVP-ChAgG fibers maintain biocompatibility and facilitate controlled therapeutic delivery, positioning them as a promising solution for managing chronic and burn-related wounds. This study underscores the potential of these advanced materials to improve healing outcomes cost-effectively, particularly in settings plagued by high incidences of burn injuries. Further clinical investigations are recommended to explore these innovative fibers' full potential and real-world applicability.

Cellulose Nanocrystal-in-Solvent Processing for Efficient One-Pot Upcycling of Commercial Polymeric PFAS.

Upcoming regulations aim to ban per- and polyfluoroalkyl substances (PFAS), including commercial polymeric PFAS, or fluoropolymers, such as poly(tetrafluoroethylene) (PTFE) and poly(vinylidene fluoride) (PVDF), due to their environmental and toxicological impacts. However, fluoropolymers also provide crucial properties for clean energy transitions, and their regulation may hinder further technological advancements. Therefore, a facile one-pot recycling-upcycling strategy for fluoropolymers using inexpensive biomass, such as cellulose nanocrystals (CNCs), as absorbents and cocomponents for fluoro-functionalized composites could align with global sustainability goals and technological demands. Herein, we present a closed-loop CNC-in-solvent (CiS) processing system, which involves stirring fluoropolymers and CNCs in only low-polarity solvents like toluene (CiS-T). Our study reveals that CiS-T is a two-step process where the CNC-solvent interaction exposes CNCs' reducing end aldehyde protons due to solvent polarity and promotes H-F bond formation. The solvent used was recollected and reused. Additionally, we demonstrate the practical application of PTFE- and PVDF-CNC hybrids, byproducts of the CiS-T process, as performance-enhancing agents in green-energy-harvesting devices such as triboelectric nanogenerators. Our findings not only offer a sustainable method to overcome challenges from regulations against commercial fluoropolymers but also offer insights into developing an efficient, solvent-mediated CNC functionalization process that addresses forthcoming challenges in key industries.

Heralded Generation of Correlated Photon Pairs from CdS/CdSe/CdS Quantum Shells.

Quantum information processing demands efficient quantum light sources (QLS) capable of producing high-fidelity single photons or entangled photon pairs. Single epitaxial quantum dots (QDs) have long been proven to be efficient sources of deterministic single photons; however, their production via molecular-beam epitaxy presents scalability challenges. Conversely, colloidal semiconductor QDs offer scalable solution processing and tunable photoluminescence, but suffer from broader linewidths and unstable emissions. This leads to spectrally inseparable emission from exciton (X) and biexciton (XX) states, complicating the production of single photons and triggered photon pairs. Here, we demonstrate that colloidal semiconductor quantum shells (QSs) achieve significant spectral separation (∼75-80 meV) and long temporal stability of X and XX emissive states, enabling the observation of exciton-biexciton bunching in colloidal QDs. Our low-temperature single-particle measurements show cascaded XX-X emission of single photon pairs for over 200 s, with minimal overlap between X and XX features. The X-XX distinguishability allows for an in-depth theoretical characterization of cross-correlation strength, placing it in perspective with photon pairs of epitaxial counterparts. These findings highlight a strong potential of semiconductor quantum shells for applications in quantum information processing.

Size-Resolved Shape Evolution in Inorganic Nanocrystals Captured via High-Throughput Deep Learning-Driven Statistical Characterization.

Precise size and shape control in nanocrystal synthesis is essential for utilizing nanocrystals in various industrial applications, such as catalysis, sensing, and energy conversion. However, traditional ensemble measurements often overlook the subtle size and shape distributions of individual nanocrystals, hindering the establishment of robust structure-property relationships. In this study, we uncover intricate shape evolutions and growth mechanisms in Co3O4 nanocrystal synthesis at a subnanometer scale, enabled by deep-learning-assisted statistical characterization. By first controlling synthetic parameters such as cobalt precursor concentration and water amount then using high resolution electron microscopy imaging to identify the geometric features of individual nanocrystals, this study provides insights into the interplay between synthesis conditions and the size-dependent shape evolution in colloidal nanocrystals. Utilizing population-wide imaging data encompassing over 441,067 nanocrystals, we analyze their characteristics and elucidate previously unobserved size-resolved shape evolution. This high-throughput statistical analysis is essential for representing the entire population accurately and enables the study of the size dependency of growth regimes in shaping nanocrystals. Our findings provide experimental quantification of the growth regime transition based on the size of the crystals, specifically (i) for faceting and (ii) from thermodynamic to kinetic, as evidenced by transitions from convex to concave polyhedral crystals. Additionally, we introduce the concept of an "onset radius," which describes the critical size thresholds at which these transitions occur. This discovery has implications beyond achieving nanocrystals with desired morphology; it enables finely tuned correlation between geometry and material properties, advancing the field of colloidal nanocrystal synthesis and its applications.

Optimizing the Production of Bacterial Cellulose Nanofibers and Nanocrystals Through Strategic Fiber Pretreatment.

Bacterial cellulose (BC) has unique properties such as high tensile strength, high crystallinity, and high purity. The fiber length of BC causes different attributes. Therefore, the degradation of BC has been studied extensively. In this study, the fibers of BC were rearranged via a DMAc-LiCl solvent and BC was degraded in the wet state. Two different degradation methods were applied: milling with liquid nitrogen and autoclave treatment. The degraded BCs were characterized by FTIR, TEM, AFM, TGA, and XRD. The solvent helps to align the fibers, making them more crystalline. The degraded BCs had a lower crystalline ratio than untreated BC, due to increased hydrogen bonding during degradation in the wet state. Degradation with an autoclave produced two different degraded BCs: nanofibrils and spherical nanocrystals, with and without solvent pretreatment, respectively. The nanofibril lengths were between 312 and 700 nm depending on the applied method, and the spherical nanocrystal size was 56 nm. The rearrangement via solvent causes an important difference in the degradation of BC. Nanofibrils and nanocrystals can be obtained, depending on the rearrangement of fibers before the degradation process.

Colloidal Ag2SbBiSe4 nanocrystals as n­type thermoelectric materials.

Materials with low intrinsic thermal conductivity are essential for the development of high-performance thermoelectric devices. At the same time, the solution processing of these materials may enable the cost-effective production of the devices. Herein, we detail a high-yield and scalable colloidal synthesis route to produce Ag2SbBiSe4 nanocrystals (NCs) using amine-thiol-Se chemistry. The quaternary chalcogenide material is consolidated by a rapid hot-press maintaining the cubic crystalline structure. Transport measurements confirm that n-type Ag2SbBiSe4 exhibits an inherently ultralow lattice thermal conductivity of ca. 0.34 W m-1K-1 at 760 K. Moreover, a modulation doping strategy based on the blending of semiconductor Ag2SbBiSe4 and metallic Sn NCs is demonstrated to control the charge carrier concentration in the final composite material. The introduction of Sn nanodomains additionally blocks phonon propagation thus contributing to reducing the thermal conductivity of the final material. Ultimately, a peak thermoelectric figure of merit value of 0.64 at 760 K is achieved for n-type Ag2SbBiSe4-Sn nanocomposites that also demonstrate a notable Vickers hardness of 185 HV.

Enhancement of therapeutic efficacy of Brinzolamide for Glaucoma by nanocrystallization and tyloxapol addition.

BACKGROUND: Brinzolamide (BRI) suspensions are used for the treatment of glaucoma; however, sufficient drug delivery to the target tissue after eye drop administration is hampered by poor solubility. To address this issue, we focused on nanocrystal technology, which is expected to improve the bioavailability of poor-solubility drugs, and investigated the effect of BRI nanocrystal formulations on corneal permeability and intraocular pressure (IOP)-reducing effect. METHODS: BRI nanocrystal formulations were prepared by the wet-milling method with beads and additives. The particle size was measured by NANOSIGHT LM10, and the morphology was determined using a scanning probe microscope (SPM-9700) and a scanning electron microscope (SEM). Corneal permeability was evaluated in vitro using a Franz diffusion cell with rat corneas and in vivo using rabbits, and the IOP-reducing effect was investigated using a rabbit hypertensive model. RESULTS: The particle size range for prepared BRI nanocrystal formulation was from 50 to 300 nm and the mean particle size was 135 ± 4 nm. The morphology was crystalline, and the nanoparticles were uniformly dispersed. In the corneal permeability study, BRI nanocrystallization exhibited higher corneal permeability than non-milled formulations. This result may be attributed to the increased solubility of BRI by nanocrystallization and the induction of energy-dependent endocytosis by the attachment of BRI nanoparticles to the cell membrane. Furthermore, the addition of tyloxapol to BRI nanocrystal formulation further improved the intraocular penetration of BRI and showed a stronger IOP-reducing effect than the commercial product. CONCLUSIONS: The combination of BRI nanocrystallization and tyloxapol is expected to be highly effective in glaucoma treatment and a useful tool for new ophthalmic drug delivery.

Liquid crystal phase behavior of oxalated cellulose nanocrystal and optical films with controllable structural color induced by centripetal force.

Cellulose nanocrystal (CNC) is a sustainable bio-nanomaterial. The distinctive left-handed polarization properties render cellulose nanocrystal a promising candidate for optical film. Due to eco-friendliness, reliability, mildness and simplicity, the oxalate hydrolysis method stands out among various preparation methods for CNC. This study delved into the liquid crystal phase behavior of oxalated cellulose nanocrystal derived from pulp, and discovered the influences of CNC concentration and pH on suspension stability and phase transition, and evaluated its optical properties. The results demonstrated that oxalated CNC presented two different liquid crystal phases, the nematic phase and the cholesteric phase. The stability mechanism of CNC suspension and the regulatory principle of the liquid crystal phase transition were revealed. A novel CNC film-forming technology, the multilayer spin-coating technique, was developed for cellulose nanocrystal optical films. Driven by centrifugal force, cellulose nanocrystals were induced to self-assembly and formed the optical film with circular dichroism and structural color. This simple and efficient film-forming technology promised rapid processing (1 h) and controllable film structure and optical properties compared to traditional technologies. This work provided a theoretical understanding and practical prospects for integrating oxalated cellulose nanocrystal into sustainable advanced optical film materials.

High performances of cellulose nanocrystal based bicomponent supramolecular hydrogel lubricant.

To improve the limitations of water-based lubricants, a novel cellulose nanocrystal based supramolecular hydrogel (CNC/x-DG/y) was prepared by mixing cellulose nanocrystal (CNC) and diglycerol (DG) into deionized water (DW). The hydrogel was characterized to determine its material ratio and gelation mechanism. When DW was fixed at 1 mL, CNC content should be no <2.4 wt% and DG content 0.1-1.3 mL. The gelification was driven by the multiple H-bond network between CNC and DG, which immobilized water molecules. The rheological performances, the anti-rust property and the volatilization behaviour of the hydrogel were further studied. The results showed that the hydrogel had satisfactory viscoelasticity, excellent thermal stability, strong creep recovery, high anti-rust performance and low volatilization rate, which were exactly its advantages for use as lubricant. A typical representative of the hydrogel, namely CNC/2.4-DG/0.1, was selected to evaluate the tribological performances, and the resulting worn surfaces were analyzed. CNC/2.4-DG/0.1 exhibited a lower friction coefficient of 0.059 and a smaller wear volume of 0.81 × 10-3 mm3, compared to DW(1 mL) + CNC(2.4 wt%) and DW(1 mL) + DG(0.1 mL). The outstanding tribological performances of CNC/2.4-DG/0.1 were reasonably attributed to the synergistic mending effect of CNC and DG and the dissipative effect of H-bonds between the two.

Effect of Chrysin and Chrysin Nanocrystals on Chlorpyrifos-Induced Dysfunction of the Hypothalamic-Pituitary-Testicular Axis in Rats.

AIMS AND BACKGROUND: The escalating global concerns regarding reproductive health underscore the urgency of investigating the impact of environmental pollutants on fertility. This study aims to focus on Chlorpyrifos (CPF), a widely-used organophosphate insecticide, and explores its adverse influence on the hypothalamic-pituitary-testicular axis in Wistar male rats. This study explores the potential protective effects of chrysin nanocrystal (CHN), a flavonoid with known antioxidant and anti-inflammatory properties, against CPF-induced impairments in male Wistar rats. METHODS: Chrysin nanocrystals were prepared using a solvent precipitation method. Six sets of male Wistar rats were subjected to 30 days of treatment, comprising a control group, a group treated solely with CPF, groups treated with CHN at doses of 5 mg/kg and 10 mg/kg, and groups co-treated with CPF and CHN. Serum levels of reproductive hormones, enzyme biomarkers of testicular function, oxidative stress, and inflammatory biomarkers were assessed. Additionally, histological examinations were conducted on the hypothalamus, testes, and epididymis. RESULTS: CHN exhibited antioxidant and anti-inflammatory properties, effectively counteracting CPF-induced reductions in Luteinizing Hormone (LH), serum testosterone, Follicle-Stimulating Hormone (FSH), and testicular enzyme biomarkers. Moreover, CHN enhanced antioxidant defenses, as evidenced by decreased malondialdehyde (MDA) and increased glutathione (GSH) levels in the hypothalamus, and testes, epididymis. Inflammatory markers, including nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α), were significantly reduced in CHN co-treated groups compared to the CPF-only group. Histopathological analyses confirmed the protective effects of CHN on tissue integrity. CONCLUSION: Chrysin nanocrystal demonstrated promising potential in mitigating CPF-induced reproductive deficits in male rats through its anti-inflammatory and antioxidant properties. This study provides valuable insights into therapeutic interventions against environmental toxin-induced reproductive toxicity, emphasizing the potential of chrysin nanocrystals as a protective agent in the context of CPF exposure.

Twist elastic constant of chiral nematic cellulose nanocrystals determined by tactoid reconfiguration in electric field.

Lyotropic chiral nematic cellulose nanocrystals (CNCs) have attracted significant attention and great progress has been made. Investigating their physical parameters, especially the twist elastic constant (K22), is pivotal for advancing our comprehension of fundamental viscoelastic property of chiral nematic phase. In this study, we demonstrate a straightforward method to simultaneously estimate K22 and helical twisting power (Kt) of chiral nematic CNCs. This method involves analyzing rheology properties and electro-response of CNCs, focusing on the rotational dynamics and structural reconfiguration of CNC tactoids under an electric field. By examining the rotation dynamics of CNC tactoids under an electric field, together with the viscosity characterization, the anisotropic dielectric susceptibility (∆χ) of chiral nematic CNC along the helix axis was determined. Subsequently, K22/∆χn was extracted by analyzing CNC tactoid pitch evolution under an electric field, employing the de Gennes model. The K22 for different concentrated CNCs is finally estimated by integrating experimental results and theory. It is shown that the chiral nematic CNCs present concentration-dependent K22, ranging from 0.05 to 0.14 pN, while Kt spans from 0.06 to 0.14 pN/µm. This study offers a comprehensive understanding of the CNC fundamental viscoelastic property and opens up new avenues for K22 measurement in other lyotropic liquid crystals.

Hierarchical Interfacial Construction by Grafting Cellulose Nanocrystals onto Carbon Fiber for Improving the Mechanical Performance of Epoxy Composites.

Carbon fiber-reinforced composites have been widely used in the aerospace industry because of their superior comprehensive performance, including high strength, low density, fatigue resistance, long service life, etc. The interface between the fiber reinforcement and the matrix is one of the key factors that determines the performance of the composites. The construction of covalent bonding connections between the components has proven to be an effective strategy for improving the interfacial bonding strength but always reduces the toughness. In this work, dual silane coupling agents are applied to covalently connect cellulose nanocrystals (CNCs) onto carbon fibers, constructing hierarchical interfacial connections between the fibers and the epoxy matrix and significantly improving the interfacial bonding strength. As a result, the tensile strength of the epoxy composites increased from 519 MPa to nearly 900 MPa, which provides a potential approach for significantly improving the mechanical performance of composites.