Nanocellulose Films Research Articles

Effects of plant source selection and chemi-mechanical treatment on the fiber microstructures and mechanical behaviors of nanocellulose films

Effects of plant source selection and chemi-mechanical treatment on the fiber microstructures and mechanical behaviors of nanocellulose films

Reversible Photo-Responsive Hydrophobic Coating Synthesized from Lignin-Derivable Molecules on Nanocellulose Films for Packaging Applications.

Paper-based packaging can offer a sustainable replacement for plastics. However, paper provides a poor barrier to water, oxygen and moisture. This study presents a novel renewable lignocellulosic composite made from a hydrophobic photo-reversible coating deposited onto a cellulose nanofiber film that has improved barrier properties and can be reprocessed. Diglycerol and lignin-derivable aldehyde were reacted to form a tetra-functional monomer with photo-responsive unsaturated double bonds that can be converted to covalent cyclobutane rings to create reversibly crosslinkable network upon UV-irradiation. The photo-responsive compound was applied as a thin coating of thickness 2.7±0.4 μm over cellulose nanofiber (CNF) films of thickness 80±19 μm. The surface of the coated films became hydrophobic with a contact angle (CA) of 93.1±1.7° and displayed a low water vapour transmission rate (WVTR) of 16±2 g/m2/day vs. 30.7±1.5° CA and 81±11 g/m2/day WVTR for uncoated CNF films. The coated film is also oleophobic, an attractive feature for food packaging applications. The reversible photo-reaction enables the crosslinked covalent network to be broken down to unsaturated double bonds once exposed to a higher-energy UV irradiation, allowing reprocessing and recycling. The novel coating was developed using a sustainable green synthesis method (process simple E factor 0.9).

Application of bacterial nanocellulose film loaded with sodium nitrite, sumac, and black carrot extracts to reduce sodium nitrite, extend shelf life, and inhibit Clostridium perfringens in cooked beef ham

This study aimed to develop innovative bacterial nanocellulose (BNC) films incorporated with sodium nitrite (SN), sumac extract (SE), and black carrot extract (BCE) to reduce sodium nitrite, extend shelf life, and inhibit Clostridium perfringens in cooked beef ham. The ham covered with BNC film immersed in SE (10 % w/v) + BCE (5 % w/v) + SN (125 ppm) (SE10BCE5SN125) exhibited the lowest microbial load (4.39, 4.32, 3.83, and 4.6 log cycles reductions in total viable count, lactic acid bacteria, Enterobacteriaceae, and C. perfringens, respectively) and the lowest oxidation rate (70 % reduction compared to control) on day 28 of storage. The samples covered with SE10BCE5SN125 film had also the lowest level of residual nitrite (64 % lower compered to positive control). Positive control (ham containing 120 ppm SN) and ham covered with SE10BCE5SN125 film had the highest redness. It was concluded that the films developed in this study have the potential to reduce the use of sodium nitrite in beef ham production.

Nanocellulose as Sustainable Eco-friendly Nanomaterials: Production, Characterization, and Applications

Nanocellulose is a biodegradable nanomaterial derived from lignocellulosic biomass through mechanical, chemical, or enzymatic defibrillation processes to convert wood fibers into nanofibrils. This material consists of a network of cellulosic fibrils with a wide range of diameters, offering unique properties suitable for various functional applications. Nanocellulose can act as a substrate or coating, serving as an eco-friendly alternative to synthetic plastics. Despite having good barrier properties and strong mechanical strength, nanocellulose films are still not as effective as synthetic plastics. They are used in creating barrier materials, flexible electronics, and coatings for paper products.

Modulating the Release Kinetics of Natural Product Actinomycin from Bacterial Nanocellulose Films and Their Antimicrobial Activity.

The present study aimed to create a more sustainable and controlled delivery system based on natural biopolymer bacterial nanocellulose (BNC) and bacterial natural product actinomycin (Act), with the applicative potential in the biomedical field. In order to provide improved interaction between BNC and the active compound, and thus to modulate the release kinetics, the TEMPO oxidation of BNC support was carried out. A mix of actinomycins from bacterial fermentation (ActX) were used as natural antimicrobial agents with an established bioactivity profile and clinical use. BNC and TEMPO-oxidized BNC films with incorporated active compounds were obtained and analyzed by FTIR, SEM, XPS, and XRD. The ActX release profiles were determined in phosphate-buffer solution, PBS, at 37 °C over time. FTIR analysis confirmed the improved incorporation and efficiency of ActX adsorption on oxidized BNC due to the availability of more active sites provided by oxidation. SEM analysis indicated the incorporation of ActX into the less-dense morphology of the TEMPO-oxidized BNC in comparison to pure BNC. The release kinetics of ActX were significantly affected by the BNC structure, and the activated BNC sample indicated the sustained release of active compounds over time, corresponding to the Fickian diffusion mechanism. Antimicrobial tests using Staphylococcus aureus NCTC 6571 confirmed the potency of this BNC-based system for biomedical applications, taking advantage of the capacity of modified BNC to control and modulate the release of bioactive compounds.

A low-energy, low-toxicity, hydrophobic cellulose membrane derived from waste fiber lunch boxes

Plastic film packaging is a significant contributor to plastic pollution, which has created growing demands to replace it with sustainable and environmentally-friendly cellulose films. In this study, waste bamboo fiber dinner boxes were used to produce nanocellulose films. The bamboo fiber lunch boxes were delignified and then fully cut and dissociated into fibers. A hydrophobic coating made from beeswax was developed to protect tableware. Bamboo nanocellulose films exhibited varying thicknesses, an average tensile strength of 81.4 MPa, and approximately 70 % crystallinity. After hydrophobic modification, the water contact angle increased to 103°, indicating improved water repellency. The treated film was also less toxic, making it suitable for packaging films that directly contact food. However, when acetone-diluted beeswax was used as a hydrophobic coating, the cellulose film formed after volatilization was significantly more toxic. The results demonstrated the potential in excellent hydrophobicity, strength and low toxicity of using beeswax-hydrophobic films for food-contact packaging.

Hydrophobic, ultraviolet radiation-shielding, and antioxidant functionalities of TEMPO-oxidized cellulose nanofibril film coated with modified lignin nanoparticles

In this study, lignin nanoparticles (LN) and octadecylamine-modified LN (LN-ODA) were utilized as coating materials to enhance the hydrophobic, antioxidant, and ultraviolet radiation-shielding (UV-shielding) properties of a TEMPO-oxidized nanocellulose film (TOCNF). The water contact angle (WCA) of the TOCNF was approximately 53° and remained stable for 1 min, while the modified LN-ODA-coated TOCNF reached over 130° and maintained approximately 85° for an hour. Pure TOCNF exhibited low antioxidant properties (4.7 %), which were significantly enhanced in TOCNF-LN (81.6 %) and modified LN-ODA (10.3 % to 27.5 %). Modified LN-ODA-coated TOCNF exhibited antioxidant properties two to six times higher than those of pure TOCNF. Modified LN-ODA exhibited thermal degradation max (Tmax) at 421 °C, while pure LN showed the main degradation temperature at approximately Tmax 330 °C. The thermal stability of TOCNF-LN-ODA-coated materials remained consistent with that of pure TOCNF, while the crystallinity index of the sample showed a slight decrease due to the amorphous nature of the lignin structure. The tensile strength of TOCNF was approximately 114.1 MPa and decreased to 80.1, 51.3, and 30.3 MPa for LN-ODA coating at 5, 10, and 15 g/m2, respectively.

Bio-inspired fabrication of thin films via surface amidation of TEMPO-oxidized cellulose nanocrystals for improved UV-shielding properties

Ultraviolet (UV) radiation impacts various aspects of human beings, and there has been significant interest in membrane materials with UV shielding. However, conventional ultraviolet shielding materials are typically petroleum-based polymers like polyethylene, which pose challenges in terms of degradation and reusability, leading to environmental pollution and other issues. The development of environmentally friendly bio-based UV shielding film materials from wood fiber raw materials holds immense importance for sustainable development. In this study, TEMPO-oxidized cellulose nanocellulose crystals (TOCNC) were utilized as the starting material to obtain modified nanocellulose suspension through amination with aniline and acetamide. Subsequently, nanocellulose films were prepared and characterized for their morphology and structure analysis. With the presence of carboxyl groups on TOCNC along with the incorporation of functional groups such as benzene rings, the absorption rate of the TOCNC composite film reaches 93.2 % across the entire ultraviolet absorption spectrum, significantly enhancing its UV shielding performance. The proposed film exhibits great potential for applications in UV-sensitive food packaging, electronic product packaging materials, plastic films, etc.

Water-resistant and barrier properties of poly(vinyl alcohol)/nanocellulose films enhanced by metal ion crosslinking

Polyvinyl alcohol (PVA) is a promising alternative to non-biodegradable flexible packaging materials, and nanocellulose is often used to enhance the properties of PVA films, but the composite films still have poor water resistance and barrier properties. To address this issue, iron ions (Fe3+) were introduced into PVA/cellulose nanofibrils (CNF) films, and Fe3+ formed coordination bonds with carboxyl and hydroxyl groups on the surface of CNF and PVA chains. Therefore, constructing a strong coordination crosslinking network within the film and improving the interfacial interaction between PVA and CNF. The water resistance, mechanical and barrier properties of the crosslinked films were significantly improved. Compared with the un-crosslinked film, the oxygen transmission rate (OTR) was decreased by up to 67 %, and the water swelling ratio was significantly reduced from 1085 % to 352 %. The tensile strength of the film with 1.5 wt% Fe3+ reached 41.93 MPa, which was 62 % higher than that of the un-crosslinked film. Furthermore, the composite film demonstrated good recyclability, almost recovering its original mechanical properties in two recycling tests. This simple and effective method for preparing water resistance and barrier films shows potential applications in flexible packaging areas.

A facile spinning approach towards the continuous production of aligned nanocellulose films

In this work, we present an alternative approach to cellulose nanofibril film (CNF) production, taking inspiration from the wet spinning of fibers to wet spin films. During the spinning process, a CNF suspension is injected into a coagulation bath, where the partially aligned CNF network is locked. The CNF alignment of the dry films is then detected by wide angle X-ray scattering (WAXS). The comparison between the ultimate strengths and strengths at breaks of the films produced with different process parameters, including the suspension injection rate, bath pH, and bath flow rate, indicated no significant change in mechanical properties, suggesting a reliable and constant outcome for large-scale film fabrication. Furthermore, the produced films demonstrated high total light transmittance of 93 % at the wavelength of 550 nm, making them suitable for optoelectronic applications. Polarized optical microscopy revealed that even a low degree of CNF alignment can lead to anisotropic optical properties. Moreover, an anisotropic response to humidity was observed, in which the films preferentially bend in the perpendicular direction of the CNF orientation, thus opening a way for humidity-driven actuators.

Nanocellulose/Nanoporous Silicon Composite Films as a Drug Delivery System.

Nanocellulose (NC) is a promising material for drug delivery due to its high surface area-to-volume ratio, biocompatibility, biodegradability, and versatility in various formats (nanoparticles, hydrogels, microspheres, membranes, and films). In this study, nanocellulose films were derived from "Bolaina blanca" (Guazuma crinita) and combined with nanoporous silicon microparticles (nPSi) in concentrations ranging from 0.1% to 1.0% (w/v), using polyvinyl alcohol (PVA) as a binding agent to create NC/nPSi composite films for drug delivery systems. The physicochemical properties of the samples were characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The mechanical properties and drug release capabilities were also evaluated using methylene blue (MB) as an antibacterial drug model. Antibacterial assays were conducted against S. aureus and E. coli bacteria. The results show that NC/nPSi composites with 1% nPSi increased the T50% by 10 °C and enhanced mechanical properties, such as a 70% increase in the elastic modulus and a 372% increase in elongation, compared to NC films. Additionally, MB released from NC/nPSi composites effectively inhibited the growth of both bacteria. It was also observed that the diffusion coefficients were inversely proportional to the % nPSi. These findings suggest that this novel NC/nPSi-based material can serve as an effective controlled drug release system.

Evaluation of microbial and oxidative changes of 100% Iberian Spanish salchichón in contact with a composite olive-leaf-extract food film and vacuum-packaged

Nowadays, consumer society is increasingly concerned about the environment and the foods production systems. Viable and efficient technologies that target a sustainable production are being developed in order to reduce the generation of agri-food residues, introducing them on the market on the basis of the so-called circular economy. In parallel, consumers are becoming more health conscious, demanding safe and natural products through the use of natural additives and ingredients. This study evaluated the stability of sliced ​​100% Iberian Spanish salchichón without added additives. It was wrapped in a biodegradable nanocellulose films incorporating olive leaf extract, then vacuum-packaged and stored at 5 and 25ᴼC for 90 days. The antimicrobial activity on lactic acid, aerobic mesophilic bacteria and Enterobacteriaceae was studied, as well as the evolution of lipid oxidation through the TBARS method. Significant differences were found between control and test sample during the evaluation of antimicrobial (aerobic mesophilic bacteria) and antioxidant activity at 25 °C. However, no significant differences were found during the evaluation of either antimicrobial or antioxidant activity at 5 °C. Olive leaf extract has a recognized antimicrobial and antioxidant activity tested in vitro; however, when tested in vivo and incorporated into a film, further refinements are needed to optimize the composite film and to obtain the desired effects of the extract as food preservative.

Application of Spray Coating in the Fabrication of Free Standing Nanocellulose Films and Barrier Coating on the Paper Substrates

Spray coating is a novel concept for fabricating free-standing film and producing barrier coating on paper substrates. The spraying gives comparable efficacy with vacuum filtration in terms of operation time, film quality, and process intensification approach. The smooth films created by spraying nanocellulose onto the polished impermeable surface could serve as a platform for a variety of sustainable functional devices. Finally, the application of spray-coating barriers and nanocellulose films on paper substrates is the focus of the spray-coating concept designed to create smooth nanocellulose films. One of the most important factors that affect the performance of different cellulose-based functional materials is the smoothness of nanocellulose film coated with sprays in the production of flexible and printed electronics. The uses of nanocellulose film as a high-performance barrier material and the possible replacement of synthetic plastic packaging are expanded by spray coatings. The process of creating a nanocellulose film using spray coating takes less than a minute. Compared to vacuum filtering, this method offers excellent speed potential for nanocellulose films. The wet layer of spray coating takes more than 24 hours to dry in a controlled laboratory environment, using air drying. Future research projects will improve the drying process of wet films. The film spray process serves as a proof of concept, and the quality of the film produced by this method contrasts with vacuum filtration. Studying spray coating wet film drying outside the scope of this research is not part of the scope of this study, and additional research is needed in this area. The shiny film that is created by spraying nanocellulose on the impermeable polished surface can serve as a platform for various sustainable functional devices.

High‐efficiency modification of PET by the low addition of a self‐assembled functional nanocellulose film prepared from waste paper

AbstractPolyethylene terephthalate (PET) is a conventional packaging material. Its modification has attracted immense attention in the industry and academia. Here, office waste paper, white cardboard waste, and waste corrugated paper were first employed as raw materials for cellulose nanocrystal (CNC) extraction by acid hydrolysis. Thereafter, CNC/PET composite films with various CNC additions were prepared via a self‐assembly technique. The results revealed that the CNCs formed a self‐assembled film on the PET surface via the synergistic effect of the complex interactions among the CNCs as well as between the CNCs and PET. Moreover, the CNCs improved the barrier property of PET and decreased the oxygen and water vapor transmittances of CNC/PET by 30.7% and 21.7%, respectively. Additionally, the coating of the PET surface with 0.2 wt.% CNCs extracted from the waste paper decreased the surface wettability of PET, exhibiting application potentials in the hydrophobic modification of polymers. This study realized waste paper recycling and provided a basis for constructing self‐assembled functional films on PET surfaces. The findings and insights of this study could exhibit application potentials in the fields of waste recycling and packaging materials.Highlights A functional cellulose nanocrystal (CNC) film is prepared from waste paper. Self‐assembled CNC is coated on a PET surface to form a CNC/PET composite film. The synergistic interactions among CNCs and between CNC and PET modified PET. The low addition of CNCs realized the efficiency modification of PET. The study achieves waste paper recycling and high‐value utilization.

Photoluminescent Nanocellulosic Film for Selective Hg2+ Ion Detection.

We developed a highly sensitive solid-state sensor for mercury detection by stabilizing red-sub-nanometric fluorescent gold nanoclusters (AuNC, 0.9 ± 0.1 nm diameter) with bovine serum albumin in a matrix composed of cellulose nanofibrils (CNF) (BSA-AuNC/CNF). The main morphological and optical features of the system were investigated via atomic force/transmission electron microscopy and UV-Vis/fluorescence spectroscopy. The hybrid film (off-white and highly transparent) showed strong photoluminescene under UV irradiation. The latter is assigned to the AuNC, which also increase the ductility of the emitting film, which was demonstrated for high sensitivity Hg2+ detection. When used as a sensor system, following AuNC printing on CNF hybrid films, a limit of detection <10 nM was confirmed. What is more, nanocellulose films have a high pore structure and selective separation properties, showcasing a wide range of potential applications in many fields such as water treatment and oil-water separation.

Biobased Composites from Eugenol- and Coumarin-Derived Methacrylic Latex and Hemp Nanocellulose: Cross-Linking via [2 + 2] Photocycloaddition and Barrier Properties.

A novel-biobased latex was synthesized by redox-initiated emulsion copolymerization of ethoxy dihydroeugenyl methacrylate with 5 wt % of a photosensitive methacrylate containing a coumarin group. A stable copolymer latex having 16 wt % solids content and a particle size of 53 nm was obtained. The copolymer had a T g of 29 °C and was soluble in acetone. Coatings were obtained, and the effect of UVA irradiation was tested: the light-induced cross-linking of the copolymer by [2 + 2] cycloaddition of the coumarin pendant moieties was demonstrated by UV-visible spectroscopy. As a consequence of UVA-induced cross-linking, the copolymer became insoluble in acetone. The copolymer latex was combined with hemp-derived nanocellulose to obtain composite self-standing films by simple mixing in an aqueous medium followed by casting, evaporation of water, and hot pressing. The composite films were also successfully cross-linked by [2 + 2] cycloaddition, with an enhancement of barrier properties. The water vapor transmission rate of the cross-linked composite films with up to 45 wt % nanocellulose was 5 times lower than that of the hemp nanocellulose film, while further addition of nanocellulose increased permeability.

Ultrathin Freestanding Nanocellulose Film Prepared from TEMPO-Mediated Oxidation and Homogenized Hydrogel.

This paper presents a versatile method to fabricate ultrathin nanofibrillated cellulose (NFC) films as thin as 800 nm by blade coating, which is compatible with a roll-to-roll process on a large scale. Our approach allows obtaining a dried nanocellulose film within a span of 1 h subsequent to 2,2,6,6-tetramethylpiperidine-1-oxyl radical-assisted oxidation and homogenization procedures. One of the thinnest freestanding NFC films with a thickness of 800 nm is achieved using a blade coating of nanocellulose after 72 h of oxidation followed by homogenization with a channel size of 65 μm. Incorporating water-soluble CdTe core-type quantum dots into the nanocellulose film led to a uniform emission under 385 nm UV irradiation, indicating excellent material compatibility. We anticipate nanocellulose developed in our study to be beneficial in biomimicry flying objects, environmentally friendly encapsulation, color filters, and energy storage device membranes, to name a few.

Influence of rice straw based nanocellulose loading in sodium carboxymethyl cellulose

The goal of this research is to produce renewable and biodegradable polymers based nanocomposite films. In this study, mixture of cellulose nanocrystals and cellulose nanofibers, collectively termed as nanocellulose was extracted from agricultural waste (rice straws). Nanocellulose (NC) filled sodium carboxymethyl cellulose (CMC) films were prepared via spin coating method. Various amount of NC (0, 20, 40 wt%) were added to CMC to prepare NC filled CMC nanocomposite film. Structural, chemical, morphological and thermal properties were studied through XRD, FTIR, SEM and TGA. It was found that CMC filled NC films have higher crysatllinality along UV blocking effect with 73 % visible light transmittance. Strong H-bonding between OH-group of NC and –COOH group of CMC resulted into stable and flexible nanocomposite film. Furthermore, thermal studies confirmed that strong hydrogen bonding within CMC and NC for 40 % NC filled CMC. It resulted for phase transition of nanocomposite film through fusion at higher temperature and high mass residue as compared to bare CMC and NC.

Preparation of Maleic Anhydride–Polystyrene Microsphere Cross-Linking Shikonin and Oxidized Nanocellulose Film for Freshness Monitoring

Preparation of Maleic Anhydride–Polystyrene Microsphere Cross-Linking Shikonin and Oxidized Nanocellulose Film for Freshness Monitoring

TEMPO-Oxidized Nanocellulose Films Modified by Tea Saponin Derived from Camellia oleifera: Physicochemical, Mechanical, and Antibacterial Properties.

Nanocellulose materials have been widely used in biomedicine, food packaging, aerospace, composite material, and other fields. In this work, cellulose obtained from Camellia shells through alkali boiling and subbleaching was micro-dissolved and regenerated using the DMAc (N,N-Dimethylacetamide)/LiCl system, and TOCNs (TEMPO-oxidized cellulose nanofibers) with different degrees of oxidation. The membrane was prepared by filtration of polytetrafluoroethylene (pore size 0.1 μm), and the oxidized nanocellulose film was obtained after drying, Then, the crystallinity, mechanical properties and oxygen barrier properties of the TOCN film were investigated. Furthermore, based on TS (tea saponin) from Camellia oleifera seed cake and TOCNs, TS-TOCN film was prepared by the heterogeneous reaction. The TS-TOCN film not only shows excellent oxygen barrier properties (the oxygen permeability is 2.88 cc·m-2·d-1) but also has good antibacterial effects on both Gram-negative and Gram-positive bacteria. The antibacterial property is comparable to ZnO-TOCN with the same antibacterial content prepared by the in-situ deposition method. Antioxidant activity tests in vitro showed that TS-TOCN had a significant scavenging effect on DPPH (2,2-Diphenyl-1-picrylhydrazyl) radicals. This design strategy makes it possible for inexpensive and abundant Camellia oleifera remainders to be widely used in the field of biobased materials.