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Preparation of all-cellulose composites with optical transparency using the banana pseudostem as a raw material
摘要： Biopolymers are intended to substitute the petroleum-based polymers and all-cellulose composite has emerged as a green alternative, especially if it can be prepared through a method consuming less energy and fewer chemicals. Here, a novel approach to obtain a nanocomposite film made of cellulose fibrils imbibed into a nanocellulose matrix is described. Banana pseudostem was used as raw material and characterized along with the resulting materials using scanning electron microscopy, optical microscopy and Raman spectroscopy, while the cellulose/nanocellulose film was studied through X-ray diffraction, UV–Vis-NIR spectroscopy and laser scanning microscopy. Results indicate that cellulose (fibrils) and nanocellulose (platelets), extracted from banana pseudostem were successfully purified using hydrolysis at a relatively low amount of chemicals. Transparent films made of a fibrils/nanoplatelets blend were prepared by the solution casting method, exhibiting a transmittance of & 83–88% and a crystallinity index of & 70, hence demonstrating the feasibility of this novel method to obtain cellulose/nanocellulose free-standing films.
关键词： Nanocomposites,Cellulose nanoplatelets,Cellulose/nanocellulose films,Agricultural waste,Inner pseudostem
更新于2025-11-21 11:08:12
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One-step growth of reduced graphene oxide on arbitrary substrates
摘要： Reduced graphene oxide (rGO) has inherited the outstanding electronic, optical, thermal and mechanical properties of graphene to a large extent, while maintaining sufficient chemically active sites. Therefore, it has attracted a great deal of research attention in the fields of energy storage, electronics, photonics, catalysis, environmental engineering, etc. Currently, the most popular way to prepare rGO is to reduce graphene oxide, which is obtained by modified Hummer methods using tedious treatments in a harsh environment, to rGO flakes. Industrial applications demand advanced preparation methods that can mass produce highly uniform rGO sheets on arbitrary substrates. In this work, a one-step growth process is introduced that utilizes cellulose acetate as a precursor, without any catalysts, to produce uniform ultrathin rGO films on various substrates and free-standing rGO powders. Systematic spectroscopic and microscopic studies on the resulting rGO are performed. Prototypes of electronic and optoelectronic devices, such as field effect transistors (FETs), photodetectors, and humidity sensors, are fabricated and tested, demonstrating the intriguing applications of our rGO materials across a wide range of fields.
关键词： electronic devices,reduced graphene oxide,one-step growth,cellulose acetate,optoelectronic devices
更新于2025-11-21 11:03:25
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Influence of Non-Toxic Magnetic Cellulose Nanofibers on Chitosan based Edible Nanocoating: A Candidate for Improved Mechanical, Thermal, Optical, and Texture Properties
摘要： The present work demonstrates the formulation of cellulose nanofiber (CNF) or magnetic cellulose nanofiber (mgCNF) dispersed chitosan based edible nanocoating with superior mechanical, thermal, optical and texture properties. The fabrication of mgCNF is successfully achieved through single-step co-precipitation route, where iron particles get adsorbed onto CNF. The thermal stability of mgCNF is improved considerably, where ~17% reduction in weight is observed, whereas CNF degrades completely under identical conditions. TGA analysis shows that there is an improvement in thermal stability for both CNF and mgCNF reinforced CS nanocoatings, where mgCNF provides more heat dimensional stability than CNF dispersed CS nanocoatings. Further, the edible nanocoatings are stable even at the temperature of heat treatment such as food sterilization. The mechanical property of the mgCNF dispersed chitosan (CS) shows remarkable improvement in tensile strength (57.86±14 MPa) and Young’s modulus (2348.52±276 MPa) compared to neat CS (6.27±0.7 MPa and 462.36±64 MPa, respectively). To recognize the developed materials as safe as food, the quantification of iron is made by using ICP-MS technique. It is noteworthy to mention that mgCNF coated CS help in improving the texture of cut pineapples in comparison with uncoated pineapple slices at ambient condition.
关键词： chitosan,magnetic cellulose nanofibers,cellulose nanofiber,edible nanocoating,packaging property
更新于2025-11-21 11:01:37
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Kinetic stabilization of cellulose nanocrystals in a photocurable prepolymer for application as an adhesion promoter in UV-curable coatings
摘要： Cellulose nanocrystals (CNC) at low loading levels were shown to reinforce a photocurable coating resulting in improved adhesion. A polyether polyol containing CNC at loading levels of up to 1.8 wt% was grafted with 3-isopropenyl-α,α-dimethylbenzyl isocyanate to functionalize it with a photocurable group. The nanoparticles were kinetically stabilized in the rapidly forming prepolymer of high viscosity. Photoinitiators and a difunctional reactive diluent were added to produce optically transparent coatings and free films upon irradiation by ultraviolet (UV) light. This allowed evaluation of the effects of CNC at low loading levels in a glassy polymer matrix obtained through a rapid cure system. Incorporation of CNC nanoparticles in the polymer matrix resulted in an average improvement in adhesive strength of 154% while enhancing tensile strength by an average of 16%. The technique described could be used as a new approach to reduce adhesive failure in UV-curable coatings without sacrificing their mechanical strength.
关键词： Coatings,Nanoreinforcement,UV curing,Nanocomposite,Adhesion promoter,Cellulose nanocrystals
更新于2025-11-21 11:01:37
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Tessellation of Chiral-Nematic Cellulose Nanocrystal Films by Microtemplating
摘要： In biological architectures, material properties are optimized by the hierarchical structuring of components with a multiscaled order, from the nano- to the macroscales. Such designs enable, for instance, programmed yield points that maximize toughness. However, research efforts in biomimetic materials have focused on the assembly of nano- or macrostructures individually. In this study, high strength cellulose nanocrystals (CNCs), assembled into chiral-nematically ordered structures, are tiled into a higher level, macro-sized, architecture by topographical templating. As templates, two meshed architectures with distinct feature sizes are evaluated, and the optomechanical properties of the resulting films are compared to featureless, flat, CNC films. Controlling capillary stresses arising during CNC assembly is shown to enable control over the orientation of the chiral-nematic director across the topography of the template. Tuning the specific reflections and multiscaled fracture propagation is demonstrated for the microtemplated CNC films. The latter phenomenon contributed to enhancing the toughness of the material through a high tortuosity of fracture propagation in all (x, y, z) directions. The presented findings are expected to pave the way towards the incorporation of current research in cellular metamaterials with the research focusing on the generation of nanoscaled biomimetic constructs.
关键词： tessellation,conformability,biomimetic,hierarchical,cellulose nanocrystals
更新于2025-11-21 11:01:37
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The coherence between TiO2 nanoparticles and microfibrillated cellulose in thin film for enhanced dispersal and photodegradation of dye
摘要： Microfibrillated cellulose (MFC) was used to enhance the dispersal and photocatalytic properties of TiO2 nanoparticles. With the small amount of MFC (0.1 wt.% or 0.3 wt.%), TEM images showed that particle agglomeration was greatly minimized due to the coherence between TiO2 nanoparticles and MFC. The surface area and pore volume of TiO2 nanoparticles was enhanced as proven in N2 adsorption-desorption analysis. Thermogravimetric and Fourier transform infrared spectra further confirmed the presence of MFC in TiO2/MFC coating solution. Using commercial adhesive, TiO2 and TiO2/MFC were spray coated on polyvinyl chloride sheet. The photocatalytic thin films were examined using scanning electron microscope with Energy dispersive X-ray analysis. The presence of MFC was not only helpful to enhance particle dispersal but also supportive to increase the hydrophilicity of the thin film. In comparison to TiO2 coating, the films were capable to adsorb 50% more methylene blue in 90 min. TiO2/MFC coatings removed 90% of methylene blue dye in 90 min under UV irradiation.
关键词： Spray coating,Photocatalysis,Dye,TiO2 nanoparticles,Microfibrillated cellulose,Adsorption
更新于2025-11-19 16:56:35
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A flexible surface-enhanced Raman substrates based on cellulose photonic crystal/Ag-nanoparticles composite
摘要： Surface-enhanced Raman scattering (SERS) significantly increases Raman scattering intensity. SERS usually uses rough-surface nano-metal materials such as gold, silver and copper as a substrate [1]. It has been widely used in surface science, analytical science and other fields [2-4]. According to the preparation method, SERS substrates can be divided into three categories: (1) solid phase substrates with fixed metal nanoparticles [5, 6]; (2) metal nanostructures prepared by nanoimprinting [7, 8]; (3) metal nanostructures prepared by template method [9-11]. Conventional SERS substrates, such as roughened surfaces of noble metals, are difficult to control and the SERS effect is unstable due to the random distribution of nanostructures. The microstructure of the nanometer regular pattern, which is processed by etching and electron beam deposition, is limited by the high cost of the instrument, the complicated production process, the difficulty to make large area and the subsequent modification of the surface. The SERS substrate prepared by a template of nanospheres array has a good controllability and reproducibility. By assembling nanospheres with different sizes to prepare the templates of different thicknesses, 2D metal films with different spacing can be obtained. The preparation of SERS substrate based on nanospheres array is simple and has low cost, easy regulation and high reproducibility. Protective agent and surfactant are not required in the preparation, meanwhile, the obtained substrate is relatively pure. PhCs are periodic structures which can be generated by a controllable self-assembly method of the spherical colloidal particles [12-15]. Light propagated inside PhCs follows Bragg's law of diffraction [16-19]. The characteristics of PhCs strongly depend on the spatial structure. Because of its cost-efficiency and easy preparation, PhC has attracted significant attentions in the application of optical sensors, optical switches [20, 21] and display devices [22-26]. The regular periodical structures can also be used as template to prepare other structural functional materials [27]. A lot of researches on the preparation and application of PhCs have been carried out in our recent work [28, 29]. Based on the special capture effect of PhC optical bandgap, the plasma effect of silver nanoparticles and the enrichment of cellulose matrix on analytes in organic solvents, we designed a combination of three properties for enhancing Raman scattering. Design concept is as follows: a PhC array which bandgap matches the incident light is used as a template, filled with a cellulose matrix that is easily degraded, and modified with silver nanoparticles. Based on the above design, a novel surface-enhanced Raman scattering substrate made by Ag-nanoparticles modified flexible cellulose photonic crystal film was firstly prepared. We synthesized an Ag-nanoparticles modified PhCs methylcellulose film (Ag-PHC-MCF) and carboxymethyl cellulose film (Ag-PHC-CMCF) SERS flexible substrates using the PhCs as templates. The innovative combination of metal nanoparticles and the ordered PhCs cellulose film (PHCCF) effectively avoided the aggregation of metal nanoparticles, as a result, the hot spots of the metal nanoparticles were distributed around the pores to ensure the uniform adsorption of the target analytes and uniform Raman signals on a large area. Through the excellent enrichment of cellulose film with pore structures, the targets in the organic solvent were captured on the cellulose film, so the Raman detection signals of the analyte were enhanced with the contact probability between the targets and the hot spots of metal nanoparticles increasing. At the same time, the light scattered on the PHCCF was enhanced significantly because of the trapping effect of PhC. Based on the original combination of the enrichment of porous methylcellulose, the plasmon resonance of Ag and the bandgap of photonic crystal, the composite film has a significant enhancement of the Raman signals. Simultaneously, due to its good degradability, it also has outstanding advantages in environmental protection. Meanwhile, it is easy to be carried and preserved because of its flexibility and light texture, which has great superiorities in transportation and storage.Therefore, it is of great significance in industrial pollutant detection or national defense safety monitoring.
关键词： SERS,cellulose films,photonic crystal,plasmonic responses
更新于2025-11-14 15:27:09
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Composite up-conversion luminescent films containing a nanocellulose and SrF2:Ho particles
摘要： The synthesis of up-conversion luminescent composite films based on a nanocellulose matrix containing Sr1-xHoxF2+x particles was proposed. The combination of sulfuric acid hydrolysis and ultrasonication allowed us to synthesize a series of stable nanocellulose dispersions from various raw materials (powdered sulphate bleached wood pulp, Blue Ribbon filter paper, and microcrystalline cellulose Avicel). The size distribution of cellulose nanoparticles in the aqueous dispersions was determined. Cellulose nanocrystals (CNC) and/or cellulose nanofibrils (CNF) dispersions were used to fabricate thin films by solution casting followed by solvent evaporation under ambient conditions. The size and shape of cellulose nanoparticles, surface morphology, crystallinity index of nanocellulose, polymerization degree, and optical properties were studied. By mixing aqueous dispersions of CNC with up-conversion Sr1-xHoxF2+x particles, homogeneous suspensions were obtained. Finally, a solution casting technique was used to prepare CNC/Sr1-xHoxF2+x and CNC/CNF/Sr1-xHoxF2+x nanocomposite films. CNC/CNF dispersions were utilized for the production of flexible, durable, transparent composite films. The synthesized nanocomposites demonstrated intense red luminescence upon Ho3+ excitation by 1912 nm laser radiation. The obtained up-conversion luminescent composite films can be considered as a promising material for photonics, in particular for near-IR laser labeling and radiation visualization, luminescent sensorics.
关键词： Nanocomposites,Up-conversion luminescent films,Cellulose nanofibrils,Cellulose nanocrystals,SrF2:Ho3+
更新于2025-09-23 15:23:52
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Biocompatible pure ZnO nanoparticles-3D bacterial cellulose biointerfaces with antibacterial properties
摘要： In this paper, we present for the first time the obtaining and characterization of new antibacterial and biocompatible nano-ZnO–bacterial cellulose (BC) material with controlled interfaces for studying in vitro microorganisms (Escherichia Coli (ATCC 8737), B. subtilis Spizizenii Nakamura (ATCC 6633), Candida albicans (ATCC10231)) and mammalian cells (human dermal fibroblast cells) response. The use of BC based material with controlled characteristics in terms of quantity and distribution of ZnO onto BC membrane (with 2D and 3D fibers arrangement) is directly correlated with the surface chemical and topographical properties, the method of preparation, and also with the type of cells implied for the specific application within the bioengineering fields. In our study, the uniform distribution and the control on the quantity of ZnO nanoparticles onto 3D BC were obtained using matrix assisted pulsed laser evaporation (MAPLE) method. The influence on particle distribution onto 3D bio cellulose were investigated based on two types of solvents (water and chloroform) involved in target preparation within MAPLE deposition. The attachment of the nanoparticles to the bacterial cellulose surface and fibrils was demonstrated by SEM and FT-IR studies. The BC-ZnO showed both resistance to bacteria-sticking and non-cytotoxic effect on the human dermal fibroblasts cells at a mass distribution onto surface of 1.68 mg ZnO NPS/mm2. These results represent a good premise in terms of tailoring BC substrates with ZnO particles that could determine or enhance both the biocompatibility and antibacterial properties of BC-composite materials.
关键词： Antibacterial effect,Zinc oxide nanoparticles,MAPLE deposition technique,Bacterial cellulose,Biocompatibility
更新于2025-09-23 15:23:52
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Cellulose/BaTiO3 aerogel paper based flexible piezoelectric nanogenerators and the electric coupling with triboelectricity
摘要： Flexible piezoelectric nanogenerators (PENGs) with high output performance are highly desirable for energy harvesting. Coupling triboelectric nanogenerators (TENGs) with the PENGs is a feasible method to enhance the output performance, while the complicated structure and the requirement of skillful operation limited the development of hybridized nanogenerators. In this work, flexible high-performance PENGs are developed using regenerated cellulose/BaTiO3 (C/BT) aerogel papers based polydimethylsiloxane (PDMS) nanocomposites. Benefiting from the high loading but uniform dispersion of tetragonal BT nanoparticles and the enhanced Young Modulus of the nanocomposites, the PENGs can exhibit a maximum voltage of 15.5 V and a maximum power of 11.8 μW under an external mechanical impact. By introducing a single electrode TENG, an innovative hybridized nanogenerator has been designed and prepared, which combine different mechanical energy harvesting techniques in a single device. Polarized along proper direction of the PENG, the positive coupling effect can efficiently increase the output voltage and power of the hybridized nanogenerator to 48 V and 85 μW, respectively. This research offers new insights into the design and preparation of high output hybridized nanogenerator with simple structure, high flexibility and easy operation.
关键词： Nanocomposites,BaTiO3 nanoparticles,Cellulose,Piezoelectricity,Hybridized nanogenerator,Triboelectricity
更新于2025-09-23 15:23:52