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The review aims at reporting on recent developments in nanocellulose-based materials and their applications in packaging with special focus on oxygen and water vapor barrier characteristics. Nanocellulose materials, including cellulose nanocrystals (CNC), nanofibrillated cellulose (NFC), and bacterial nanocellulose (BNC), have unique properties with the potential to dramatically impact many commercial markets including packaging. In addition to being derived from a renewable resource that is both biodegradable and non-toxic, nanocellulose exhibits extremely high surface area and crystallinity and has tunable surface chemistry. These features give nanocellulose materials great potential to sustainably enhance oxygen and water vapor barrier properties when used as coating, fillers in composites and as self-standing thin films. [ABSTRACT FROM AUTHOR]

[Display omitted] • Evaluated paper mill sludge waste conversion into value added packaging materials. • Enzymatic pretreatment enhanced micro- and nanofibrillated cellulose (MNFC) production. • Enzymatic hydrolysis and mechanical centrifugation showed a synergistic effect. • The presence of inorganics improves MNFC preparation and composite formation. • Sludge MNFC-derived packaging films showed high mechanical strength. The production of micro- and nano-fibrillated cellulose (MNFC) from paper mill sludge (PS) using simple enzymatic and mechanical treatments has been evaluated for their performance as value-added materials in packaging and other applications. Sludge from a US paper mill was analyzed for the viability of this conversion process. The enzymatic treatment was conducted at variable concentrations using an enzyme cocktail of exoglucanase and endoglucanase, followed by mechanical dual asymmetric centrifugation (DAC) treatment. The presence of inorganics and lignin facilitated the mechanical defibrillation of the fibers, making the MNFC production more energy-efficient. The prepared MNFC was characterized for fibrillation, charge, crystallinity, and surface morphology. Scanning electron microscopic (SEM) images show the highly fibrillated MNFC and the distribution of inorganic nanoparticles on the fiber surface. The X-ray diffractometric (XRD) analysis shows 44–65 % crystallinity. Furthermore, MNFC-based films derived from PS demonstrated excellent strength and flexibility, making them suitable for packaging and other applications. Overall, this conversion approach can save the paper industry millions of dollars in disposal costs while upcycling waste and reducing greenhouse gas (GHG) emissions associated with waste streams. [ABSTRACT FROM AUTHOR]

The technology of food packaging is responding to significant market dynamics such as the rapid growth in e-commerce and preservation of fresh food, a sector that accounts for over 40% of plastic waste. Further, mandates for sustainability and recent changes in national governmental policies and regulations that include banning single-use plastic products as observed in sweeping reforms in Europe, Asia, and several US States are forcing industries and consumers to find alternative solutions. This review highlights an ongoing shift of barrier coatings from traditional synthetic polymers to sustainable breakthrough materials for paper-based packaging and films. Advantages, challenges and adapting feasibility of these materials are described, highlighting the implications of selecting different materials and processing options. A brief description on progress in methods of coating technologies is also included. Finally, the end fate of the barrier materials is classified depending on the packaging type, coating materials used and sorting facility availability. Different types of coatings, such as water-based biopolymers, due to their greater environmental compatibility, are making inroads into more traditional petroleum-based wax and plastic laminate paperboard products for fresh food bakery, frozen food, and take-out containers applications. In addition, nano-biocomposites have been studied at an accelerating pace for developing active and smart packaging. Based on the momentum of recent developments, a strong pace of continuing developments in the field can be expected. [Display omitted] • Top trends in food packaging are driven by sustainability, e-commerce, and the end fate of the materials. • Recent developments in bio-based materials have the potential of replacing petro-based polymers. • High speed and specialized coating methods have emerged in the past few years for food packaging development. • Businesses are focused on the recycling of synthetic and biopolymers. [ABSTRACT FROM AUTHOR]

Optimizing drying energy in the forest products industry is critical for integrating lignocellulosic feedstocks across all manufacturing sectors. Despite substantial efforts to reduce thermal energy consumption during drying, further enhancements are possible. Cellulose, the main component of forest products, is Earth's most abundant biopolymer and a promising renewable feedstock. This study employs all-atom molecular dynamics (MD) simulations to explore the structural dynamics of a small I β -cellulose microcrystallite and surrounding water layers during drying. Molecular and atomistic profiles revealed localized water near the cellulose surface, with water structuring extending beyond 8 Å into the water bulk, influencing solvent-accessible surface area and solvation energy. With increasing temperature, there was a ∼20 % reduction in the cellulose surface available for interaction with water molecules, and a ∼22 % reduction in solvation energy. The number of hydrogen bonds increased with thicker water layers, facilitated by a "bridging" effect. Electrostatic interactions dominated the intermolecular interactions at all temperatures, creating an energetic barrier that hinders water removal, slowing the drying processes. Understanding temperature-dependent cellulose-water interactions at the molecular level will help in designing novel strategies to address drying energy consumption, advancing the adoption of lignocellulosics as viable manufacturing feedstocks. [Display omitted] [ABSTRACT FROM AUTHOR]

Climate changes, emerging species of plant pests, and deficits of clean water and arable land have made availability of food to the ever-increasing global population a challenge. Excessive use of synthetic pesticides to meet ever-increasing production needs has resulted in development of resistance in pest populations, as well as significant ecotoxicity, which has directly and indirectly impacted all life-forms on earth. To meet the goal of providing safe, sufficient, and high-quality food globally with minimal environmental impact, one strategy is to focus on targeted delivery of pesticides using eco-friendly and biodegradable carriers that are derived from naturally available materials. Herein, we discuss some of the recent approaches to use biodegradable matrices in crop protection, while exploring their design and efficiency. We summarize by discussing associated challenges with the existing approaches and future trends that can lead the world to more sustainable agricultural practices. Image 1 • Providing food safety and security is critical for the growing global population. • Crop yield is affected by various biotic and abiotic factors. • Targeted/sustained delivery of agrochemicals reduces excessive use of pesticides. • Nature-derived biodegradable materials curtail plant health and environmental harm. • Biodegradable matrices hold promise for sustainable crop protection. [ABSTRACT FROM AUTHOR]

Water removal during paper manufacturing is of primary importance to production rate and cost efficiency for the pulp and paper industry. It is crucial to develop methods to reduce energy consumption by increasing the percent solids in the paper web entering the dryers from the presses. This research aimed to develop a fundamental understanding of the effect of bio-chemo-mechanical pretreatments on a bleached softwood fiber matrix and evaluate the impact on the percent solids of the paper web after pressing. Experiments included enzymatic, refining, and cationic polymer pretreatments on the bleached softwood pulps, followed by laboratory papermaking and determining the equilibrium moisture content (EMC) after pressing and the pulp and paper properties. The combined effect of mild refining, controlled enzymatic pretreatments, and cationic strength aids proved to enhance the water removal during wet pressing (up to 35 % reduction) and increase paper strength (up to 60 % increase). The results of increased solids after pressing were used to calculate the potential reduction in drying energy during paper manufacturing. Energy savings of around 10 % for paper drying could be achieved through fiber matrix modification by bio-chemo-mechanical pretreatment. Enzymatic pretreatments have previously been conventionally applied before refining as an energy-saving method. However, this research shows that synergistic actions of enzymes added after refining modify the fibers and create the optimal conditions for enhancement in drainage, press dewatering, and paper properties. [Display omitted] • Enzyme-assisted fiber modifications improve press dewatering and paper strength. • Enzyme blends can enhance fiber cell wall flexibility and fibrillation. • Synergistically, enzymes increased ∼35% press dewatering and ∼60% tensile strength. • Enzymes, mild refining, and cationic biopolymers enhance paper process efficiency. • This research introduces alternative methods for decarbonizing the paper industry. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Developed Poly(N-Isopropylacrylamide)-Cellulose Nanocrystal hydrogel films. • Achieved unique thermo-responsivity and tunable optical performance. • Developed a hybrid materials system to modulate LCST and moisture content for thermo-responsivity and optical tunability. • Demonstrated a ∼ 15 °C reduction of the LCST relative to pure PNIPAm hydrogel films. • Below the LCST, PNIPAm/CNC hydrogel films exhibit transparency or semi-transparency. Abstract A hybrid materials system to modulate lower critical solution temperature (LCST) and moisture content for thermo-responsivity and optical tunability was strategically developed by incorporating cellulose nanocrystals (CNCs) into a poly(N -isopropylacrylamide) (PNIPAm) hydrogel matrix. The PNIPAm/CNC hydrogel films exhibit tunable optical properties and wavelength bandpass selectivity as characterized by PROBE Spectroscopy and Dynamic Light Scattering (DLS). Importantly, the micro/nano structures of the PNIPAm/CNC hydrogel films were completely different when dried below and above the LCST. Below the LCST, PNIPAm/CNC hydrogel films exhibit transparency or semi-transparency due to the uniform bonding of hydrophilic PNIPAm and CNC through hydrogen bonds. Above the LCST, the hydrogel films engage in both hydrophobic PNIPAm and hydrophilic CNC interactions due to changes in PNIPAm conformation which lead to light scattering effects and hence opacity. Furthermore, the incorporation of CNC induces a ∼ 15 °C reduction of the LCST relative to pure PNIPAm hydrogel films. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A new pathway for sustainable packaging materials was engineered by formulating multilayer CNF/CNC barrier coatings. • CNF and CNC synergistically enabled high oil and grease resistance (a kit rating of 11) comparable to fluorochemicals. • A significant reduction in oxygen transmission rate was demonstrated (∼by a factor of about 260) compared to uncoated paper. • Sustainable biomaterials are relevant to society's ongoing efforts to improve health, safety, and environmental stewardship. Abstract Cellulose derivatives such as cellulose nanofibers (CNF) and cellulose nanocrystals (CNC) have enormous potential to reduce or replace petroleum and fluorochemicals for food and other packaging applications. CNFs have been studied for their excellent oxygen and gas barrier properties; however, their performance rapidly decreases in the presence of moisture and higher humidity. CNCs are less sensitive to moisture due to their highly crystalline nature; however, coatings and films made of CNCs are much more prone to fracture due to their high brittleness. Our work demonstrates a unique composite barrier coating system of CNF and CNC that synergistically enables oil and grease resistance (a kit rating of 11) comparable to fluorochemicals. It also demonstrates a significant increase in air resistance (∼by a factor of about 300), and a reduction in oxygen transmission rate (∼by a factor of about 260) compared to uncoated paper. The improvements in oil and gas barrier properties were evaluated with respect to the molecular, chemical, and structural properties of the developed coatings. [ABSTRACT FROM AUTHOR]

Flexible-hybrid printed electronics (FHPE) is a rapidly growing discipline that may be described as the precise imprinting of electrically functional traces and components onto a substrate such as paper to create functional electronic devices. The mass production of low-cost devices and components such as environmental sensors, bio-sensors, actuators, lab on chip (LOCs), radio frequency identification (RFID) smart tags, light emitting diodes (LEDs), smart fabrics and labels, wallpaper, solar cells, fuel cells, and batteries are major driving factors for the industry. Using renewable and bio-friendly materials would be advantageous for both manufacturers and consumers with the increased use of (FHPE) electronics in our daily lives. This review article describes recent developments in cellulose and nanocellulose-based materials for FHPE, and the necessary developments required to propagate their use in commercial applications. The aim of these developments is to enable the creation of FHPE devices and components made almost entirely of cellulose materials. [ABSTRACT FROM AUTHOR]

Cellulosic fiber collapse is a phenomenon of fundamental importance for many technologies that include tissue/hygiene to packaging because it governs their essential materials properties such as tensile strength, softness, and water absorption; therefore, we elaborate cellulose fiber collapse from water interactions. This is the first attempt to directly correlate fiber collapse and entrapped or hard-to-remove (HR) water content through DSC, TGA and SEM. Freeze-drying and oven drying were individually investigated for influence on collapse. SEM of the fibers at different moisture contents show that irreversible collapsing begins as entrapped water departs the fiber surface. The removal of HR water pulls cell walls closer due to strong capillary action which overwhelms the elastic force of the fiber lumen which results in partially or fully irreversible collapse. The initial moisture content and refining intensity were found to regulate HR water content and consequently played a vital role in fiber collapsing. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Extraction of lignin-containing cellulose nanofibers (LCNF) from hemp hurds waste. • Development of LCNF coatings/films with reduced polarity and low hydrophilicity. • Elucidation of the role of lignin content and distribution on barrier properties. • Significantly higher water contact angle with LCNF coatings and films. • LCNF-based coatings/films can contribute to a circular economy and sustainability. Residual hemp (Cannabis sativa) hurd fibers obtained from hydrothermal, carbonate, and kraft treatments were the resources used to obtain lignocellulosic nanofibers (LCNF) by using an ultra-fine friction grinder. The morphological, crystallinity, and chemical characteristics of the nanocellulose films were carried out using SEM, XRD, EDX and ToF-SIMS. Water barrier properties of the same were measured in terms of water contact angle, water vapor permeability (WVP) and water absorption. The barrier properties were found to be dependent not only on the lignin content and lignin distribution, but also on the film density and porous structure. LCNF films and coatings showed much higher water contact angle (WCA) (80°-102°) than films produced from the bleached CNF. WVP was found to be more dependent on the density of films than lignin content. Overall, LCNF-based films and coatings derived from hemp hurd residual fibers can contribute to a circular economy and sustainability. [ABSTRACT FROM AUTHOR]

Transparent and High Barrier Plasma Functionalized Acrylic Coated Cellulose Triacetate Films. • Fabrication of transparent and high barrier coated cellulose triacetate (CTA) films. • Enhanced adhesion and curing of acrylic coatings via atmospheric plasma treatments. • Significant reduction in WVTR while maintaining excellent transparency. • Modulation of surface texture via plasma compositions and crosslinking agents. Transparent and high moisture barrier acrylic coatings were obtained by deposition of acrylic resin containing crosslinking agents onto cellulose ester films, followed by exposure to atmospheric plasma. The effects of monomers, crosslinking agents, and polymerization methods were studied. The surface chemical composition, morphology, water vapor transmission rate (WVTR), light transmittance, and adhesion performance of the coated cellulose triacetate (CTA) films were characterized for the acrylic coated films and for different plasma treatments. Coated films showed a significant reduction in water vapor permeability while maintaining excellent transparency when compared with uncoated films. Furthermore, adhesion of the coating to the CTA film was also improved due to plasma treatment. It was also found that plasma curing on the coated oligomers can induce morphological changes and significantly increase surface roughness and hydrophilicity. The roughness texture observed via SEM analysis indicated that the types of plasma polymerization and the amount of crosslinking agents control the texture types for acrylic coating. Plasma-assisted acrylic coated CTA films can be used in electronic displays, medical, and packaging applications. [ABSTRACT FROM AUTHOR]

• Tunable poly(N-Isopropylacrylamide)-cellulose nanofibrils hydrogel films. • Fabrication using inverted SLA 3D printing to provide a new manufacturing platform. • Switchable bio-adhesion to bacteria depending on the CNF content and distribution. • Unique thermo-responsivity and tunable optical performance. • Modulation of LCST (∼ 8 °C reduction) relative to pure PNIPAm hydrogel films. A hybrid poly(N-isopropylacrylamide) (PNIPAm)/cellulose nanofibrils (CNFs) hydrogel composite was fabricated by inverted stereolithography 3D printing to provide a new platform for regulating lower critical solution temperature (LCST) properties and thus tuning optical and bioadhesive properties. The phenomena of interest in the as-printed PNIPAm/CNF hydrogels may be attributed to the fiber-reinforced composite system between crosslinked PNIPAm and CNFs. The optical tunability was found to be correlated to the micro/nano structures of the PNIPAm/CNF hydrogel films. It was found that PNIPAm/CNF hydrogels exhibit switchable bioadhesivity to bacteria in response to CNF distribution in the hydrogels. After 2.0 wt% CNF was incorporated, it was found that a remarkable 8°C reduction of the LCST was achieved relative to PNIPAm hydrogel crosslinked by TEGDMA without CNF. The prepared PNIPAm/CNF hydrogels possessed highly reversible optical, bioadhesion, and thermal performance, making them suitable to be used as durable temperature-sensitive sensors and functional biomedical devices. [ABSTRACT FROM AUTHOR]

• CNF/MWCNTs films with a structure of semi-interpenetrating networks were fabricated. • Percolation threshold level of CNF/MWCNTs membranes of 1.88 wt% was achieved. • CNF/MWCNTs films with 10 wt% MWCNTs showed a high conductivity value of 37.6 S/m. • Resistances of CNF/MWCNTs films were affected by bending states to a minor extent. • Capacitance of the pressure sensors was almost linearly dependent on pressure. Highly conductive multi-walled carbon nanotubes (MWCNTs) and flexible cellulose nanofibers (CNF) membranes with semi-interpenetrating networks structure were fabricated using the typical paper-making method, which was simple and cost-effective. The Scanning electron microscope (SEM), Fourier-transform infrared (FT-IR), and thermal gravimetric analysis (TGA) were used to estimate the morphology, chemical structure, and thermal stability of the membranes. The mechanical, optical, and electrical properties of the membranes were characterized with a uniaxial tensile testing machine, ultraviolet visible spectroscope, and digital multimeter, respectively. The results indicated that the membranes containing 10 wt% of MWCNTs showed a high conductivity value of 37.6 S/m, and the sheet resistances of the membranes were stable at different bending states. Furthermore, we demonstrated the electrical features of membrane-based capacitive pressure sensors based on CNF/MWCNTs. The proposed method for fabricating CNF/MWCNTs membranes can simplify the production process and have great practical potential in various electronics applications such as touch screens. [ABSTRACT FROM AUTHOR]