Search

Widely employed petroleum-based food packaging materials have inflicted irreparable harm on ecosystems, primarily stemming from their non-biodegradable attributes and recycling complexities. Inspired by natural nacre with a layered aragonite platelet/nanofiber/protein multi-structure, we prepared high-barrier composite films by self-assembly of cellulose nanofibrils (CNF), cellulose nanocrystals (CNC), montmorillonite (MMT), polyvinyl alcohol (PVA) and alkyl ketene dimer (AKD). The composite films demonstrated outstanding barrier properties with oxygen vapor transmission of 0.193 g·mm·m -2 ·day -1 and water vapor transmission rates of 0.062 cm 3 ·mm·m -2 ·day -1 ·0.1 MPa -1 , which were significantly lower than those of most biomass-degradable packaging materials. Additionally, the impacts of mixing nanocellulose with various aspect ratios on the tensile strength and folding cycles of the films were examined. The exceptional resistance of the composite films to oil and water provides a novel and sustainable approach to reduce non-biodegradable plastic packaging., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Structural color is an eye-catching phenomenon in nature, which originates from the synergistic effect of cholesteric structure inside living organisms and light. However, biomimetic design and green construction of dynamically tunable structural color materials have been a great challenge in the field of photonic manufacturing. In this work, the new ability of L-lactic acid (LLA) to multi-dimensionally modulate the cholesteric structures constructed from cellulose nanocrystals (CNC) is revealed for the first time. By studying the molecular-scale hydrogen bonding mechanism, a novel strategy that electrostatic repulsion and hydrogen bonding forces jointly drive the uniform arrangement of cholesteric structures is proposed. Due to the flexible tunability and uniform alignment of the CNC cholesteric structure, different encoded messages were developed in the CNC/LLA (CL) pattern. Under different viewing conditions, the recognition information of different digits will continue to reversibly and rapidly switch until the cholesteric structure is destroyed. In addition, the LLA molecules facilitated the more sensitive response of the CL film to the humidity environment, making it exhibit reversible and tunable structural colors under different humidity. These excellent properties provide more possibilities for the application of CL materials in the fields of multi-dimensional display, anti-counterfeiting encryption, and environmental monitoring., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The charge plays an important role in cellulose nanocrystal (CNC) self-assembly to form liquid crystal structures, which has rarely been systematically explored. In this work, a novel technique combining atomic force microscopy force and atomistic molecular dynamics simulations was addressed for the first time to systematically investigate the differences in the CNC self-assembly caused by external positive and negative charges at the microscopic level, wherein sodium polyacrylate (PAAS) and chitosan oligosaccharides (COS) were used as external positive and negative charge additives, respectively. The results show that although the two additives both make the color of CNC films shift blue and eventually disappear, their regulatory mechanisms are, respectively, related to the extrusion of CNC particles by PAAS and the reduction in CNC surface charge by COS. The two effects both decreased the spacing between CNC particles and further increased the cross angle of CNC stacking arrangement, which finally led to the color variations. Moreover, the disappearance of color was proved to be due to the kinetic arrest of CNC suspensions before forming chiral nematic structure with the addition of PAAS and COS. This work provides an updated theoretical basis for the detailed disclosure of the CNC self-assembly mechanism.

The preparation of carboxylated cellulose nanocrystals (cCNCs) and their stabilization in oil-in-water (O/W) Pickering emulsions hold great potential for application and research value. In this work, a novel integrated oxidation strategy was proposed to prepare needle-like cCNCs by sodium periodate (NaIO 4 )/Fenton (SF-cCNCs) with considerable yield (58.58 %), plentiful carboxyl groups (1.28 mmol/g), and high crystallinity (83.3 %). The distinctive features of smaller size and high viscosity accelerated the as-prepared SF-cCNCs to be used in stabilizing Pickering emulsion. Moreover, the effects of oil-water ratio (OWR), SF-cCNCs content, pH, and sodium chloride (NaCl) content on the stability of SF-cCNCs-stabilized Pickering emulsions were also investigated systematically. Interestingly, the stability of the as-obtained emulsions was dependent on pH and salt. Afterwards, the rheological behaviors validated that the emulsion viscosity increased rapidly after adding NaCl, which was dominated by the elastic behavior. Finally, the main stabilization mechanism was confirmed to be interfacial adsorption of SF-cCNCs rather than the formation of spatial network structures between droplets. This study reports a synthetic strategy to efficiently prepare SF-cCNCs, endowing the SF-cCNCs stabilized Pickering emulsion with environmentally friendly, long-term stable and highly anti-agglomeration abilities for cosmetics and food products., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

As a nanoscale renewable resource derived from lignocellulosic materials, cellulose nanocrystals (CNCs) have the features of high purity, high crystallinity, high aspect ratio, high Young's modulus, and large specific surface area. The most interesting trait is that they can form the entire films with bright structural colors through the evaporation-induced self-assembly (EISA) process under certain conditions. Structural color originates from micro-nano structure of CNCs matrixes via the interaction of nanoparticles with light, rather than the absorption and reflection of light from the pigment. CNCs are the new generation of photonic liquid crystal materials of choice due to their simple and convenient preparation processes, environmentally friendly fabrication approaches, and intrinsic chiral nematic structure. Therefore, understanding the forming mechanism of CNCs in nanoarchitectonics is crucial to multiple fields of physics, chemistry, materials science, and engineering application. Herein, a timely summary of the chiral photonic liquid crystal films derived from CNCs is systematically presented. The relationship of CNC, structural color, chiral nematic structure, film performance, and applications of chiral photonic liquid crystal films is discussed. The review article also summarizes the most recent achievements in the field of CNCs-based photonic functional materials along with the faced challenges., (© 2021 Wiley-VCH GmbH.)

Hornification are usually occurred in cellulosic fibers and even in nanocellulose fibrils during dehydration process but their mesoscopic structural changes is not fully understood. Here we investigated the structural features of cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNF) with different solid content. In order to avoid the effect of drying, liquid AFM mode was carried out in this work. The different water contents of nanocellulose were quantified by Differential Scanning Calorimetry (DSC). We showed evidence of extreme growth in radial direction in the redispersed nanocelluloses, analyzed by statistics of contours from microscopy images. The amount of free water, freezing bound water, and non-freezing bound water decreased gradually during water evaporation and were completely removed in sequence. In addition, the hydroxyl accessibility of both redispersed CNCs and CNF were reduced by 83.33% and 81.96% via evaluating the uptake of fluorescent dyes., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Given the widespread prevalence of viruses, there is an escalating demand for antimicrobial composites. Although the composite of dialdehyde cellulose and silver nanoparticles (DAC@Ag1) exhibits excellent antibacterial properties, its weak mechanical characteristics hinder its practical applicability. To address this limitation, cellulose nanofibers (CNFs) were initially ammoniated to yield N-CNF, which was subsequently incorporated into DAC@Ag1 as an enhancer, forming DAC@Ag1/N-CNF. We systematically investigated the optimal amount of N-CNF and characterized the DAC@Ag1/N-CNF using FT-IR, XPS, and XRD analyses to evaluate its additional properties. Notably, the optimal mass ratio of N-CNF to DAC@Ag1 was found to be 5:5, resulting in a substantial enhancement in mechanical properties, with a 139.8% increase in tensile elongation and a 33.1% increase in strength, reaching 10% and 125.24 MPa, respectively, compared to DAC@Ag1 alone. Furthermore, the inhibition zones against Escherichia coli and Staphylococcus aureus were significantly expanded to 7.9 mm and 15.9 mm, respectively, surpassing those of DAC@Ag1 alone by 154.8% and 467.9%, indicating remarkable improvements in antimicrobial efficacy. Mechanism analysis highlighted synergistic effects from chemical covalent bonding and hydrogen bonding in the DAC@Ag1/N-CNF, enhancing the mechanical and antimicrobial properties significantly. The addition of N-CNF markedly augmented the properties of the composite film, thereby facilitating its broader application in the antimicrobial field. [ABSTRACT FROM AUTHOR]

A novel strategy for spraying nanosized soil particles on steel mesh to prepare the superlyophobic soil mesh by a facile surface treatment technology, and successfully apply it to various immiscible liquids separation. [Display omitted] • A multifunctional, sustainable material for immiscible liquid mixtures separation. • Under nonpolar (polar) liquid superlyophobicity of polar (nonpolar) liquid. • Used chemical properties-structure relationships to give material performance. • Low cost manufacturing, environment friendly, dimplicity of operator. • Good corrosion resistance in acidic, alkaline and high salt environment. Immiscible liquids separation has recently become a worldwide challenge due to the expanding industrial activity. It is still thorny to put forward a universal strategy for constructing multi-superlyophobic surfaces in immiscible liquids systems due to a thermodynamic contradiction. Herein, a low-cost, environmentally friendly pre-wetted nanosized soil coated-mesh (NSCM) was prepared, which shows the property of under-nonpolar-liquid superlyophobic to polar liquid, or under-polar-liquid superlyophobic to nonpolar liquid. The NSCM was fabricated in aqueous solutions by spraying melamine formaldehyde resin modified nanosized soil particles on a stainless-steel mesh for selective immiscible liquid separation. After the NSCM is prewetted with heavy liquid, heavy liquid can be removed from the light immiscible liquid mixtures by gravity. The as-prepared NSCM showed a high separation efficiency of above 99% for a series of immiscible liquids mixtures, even after 60 separation cycles. More importantly, the electrochemical tests indicated that the NSCM exhibited the outstanding durability after being immersed in alkali (pH = 10.0, NaOH), acidic (pH = 4.0, HCl) and high-concentrated salt solutions (3.5 wt% NaCl) for 30 days. The calculated R t values were approximately 1.04 × 107, 2.65 × 106 and 7.59 × 105 Ω·cm2, respectively. And the corresponding corrosion rates were 0.013712, 0.96438, and 2.5818 μm/year, respectively. These excellent performances of the NSCM make it an ideal candidate material for separation, and even in a wider field of sea wastewater treatment. [ABSTRACT FROM AUTHOR]