Excellent UV-shielding Properties Research Articles

Design, construction and mechanism of highly efficient flame retardant, UV shielding and transparent thermoplastic polyurethanes

The rapid development of 5G communication and new energy poses great challenges to the fire safety, UV resistance, and transparent properties of TPU composites. In this study, a novel and multi-functional flame retardant ((diphenylphosphoryl)azanediyl)bis(ethane-2,1-diyl) bis(diphenylphosphinate) (DPEP) containing multiple flame retardant groups and polyaromatic structure was innovatively designed. The prepared TPU/DPEP composites exhibited excellent fire safety, UV shielding, mechanical and transparent properties. 4 wt% DPEP enabled TPU to pass the UL-94 V-0 rating and improved the LOI to 29.6 %. Compared to pure TPU, the heat release rate and total heat release of TPU/4 wt% DPEP were decreased by 29.06 % and 13.24 %. Meanwhile, TPU/DPEP composites achieved 100 % UV shielding at UV-B wavelengths and up to 68.77 % UV isolation at UV-A wavelengths. Due to the structural similarity and processing meltability, DPEP exhibited good dispersion and compatibility in TPU matrix. TPU/DPEP retained almost the same mechanical and transparent properties as pure TPU. The condensed and gas phase analysis indicated that the flame retardant mode of DPEP was mainly dominated by flame retardant inhibition and the barrier effect of the carbon layer. Compared with the reported flame retardant TPU composites, the TPU/DPEP composites achieved a relatively optimal balance between efficient flame retardant, mechanical, UV shielding, and transparent properties, demonstrating great application prospects in the emerging fields.

Sustainable strategy for lignin etherification and its promotion of anti-UV aging PLA biocomposite

Achieving efficient modification of both phenolic (Phe)-OH and aliphatic (Aliph)-OH groups in lignin simultaneously via sustainable method, remained a significant challenge. In this study, a series of highly hydroxyl-substituted alkali lignin phenyl propylene ketone ethers (ALK) were obtained under 50 °C without any by-products via the mild and sustainable hydroxyl-yne click reaction method. Notably, phenolic (Phe)-OH content of lignin decreased from 4.12 mmol g−1 to 0.07 mmol g−1 with a conversion rate of 98 %, while the aliphatic (Aliph)-OH content of lignin decreased from 2.57 mmol g−1 to 0.10 mmol g−1 with a conversion rate of 96 %. Owing to the efficient etherification, ALK showed excellent organic solvent (such as trichloromethane, DCM, THF, and acetone) solubility, which thereby improving the interfacial compatibility between ALK and PLA matrix. 3 wt% ALK obviously enhanced the mechanical properties of ALK/PLA biocomposite films, with the yield strength, breaking strength, and Young’s modulus improving by 114.2 %, 30.7 % and 250.2 %, respectively. Additionally, due to the newly introduced vinyl ether bonds (−C–O–CC–) in ALK by hydroxyl-yne click reaction, only 1 % ALK could endow ALK/PLA biocomposite with excellent UV shielding (100 %), high transmittance (84.3 %) and Anti-UV aging property. The yield strength and Young’s modulus represented an increase of 209 % and 86 %, respectively, even after 3 h of UV-irradiation. This study presents an environmentally friendly lignin functionalization method that unleashes the inherent Anti-UV aging properties of lignin, opening new avenues for the development of high-performance lignin-based composites.

Multifunctional honeysuckle extract/attapulgite/chitosan composite films containing natural carbon dots for intelligent food packaging

In order to fulfill people's requirements for food quality and safety, it is a promising strategy to develop intelligent biodegradable food packaging materials. Herein, honeysuckle extracts/attapulgite/chitosan composite films containing natural carbon dots were fabricated for intelligent food packaging. Different characterization techniques were employed to study the obtained composite films, while the physicochemical properties, optical properties, antibacterial and antioxidant activities of composite films were determined. The obtained composite films presented good mechanical, antibacterial and antioxidant properties, and the antibacterial ratios of composite films against Escherichia coli and Staphylococcus aureus were 99.27 ± 0.18 % and 98.85 ± 0.65 %, respectively. When the added amount of honeysuckle extracts/attapulgite nanocomposites was 4.76 %, the tensile strength and elongation at break of composite films reached 24.9 ± 2.35 MPa and 64.8 ± 2.11 %, respectively, which were obviously higher than that of pure chitosan film. Furthermore, the composite films exhibited excellent UV shielding and blue fluorescence properties, as well as pH-sensitivity due to the presence of caffeoquinic acid-based natural carbon dots derived from honeysuckle extract. Therefore, the composite films indicated a potential application for intelligent food packaging.

Flexible cellulose nanofibers/MXene composite films for UV-shielding packaging

Cellulose nanofibers (CNF) based films are promising packaging materials, but the lack of special functions (especially UV-shielding property) usually restrict their further applications. In this work, MXene was incorporated into the CNF film by a direct solvent volatilization induced film forming method to study its UV-shielding property for the first time, which avoided the using of a vacuum filtration equipment. The composite films containing glycerin could be folded repeatedly without breaking, showing good flexibility. The structure and properties of MXene/CNF composite films (CMF) were characterized systematically. The results showed that MXene distributed uniformly in the CNF film matrix and there was strong hydrogen bonding interaction between CNF and MXene. The tensile strength and Young's modulus of the composite films could reach 117.5 MPa and 2.23 GPa, which was 54.1 % and 59.2 % higher than those of pure CNF film, respectively. With the increase of MXene content, both the UVA and UVB shielding percentages increased significantly from 17.2 % and 25.5 % to 100.0 %, showing excellent UV-shielding property. Moreover, CMF exhibited a low oxygen permeability (OP) value of 0.39 cc μm d−1 m−2 kPa−1, a low water vapor permeability (WVP) value of 5.13 × 10−11 g−1s−1Pa−1 and a high antibacterial rate against E. coli (94.1 % at 24 h), showing potential application in the packaging field.

Environment-friendly, high-performance cellulose nanofiber-vanillin epoxy nanocomposite with excellent mechanical, thermal insulation and UV shielding properties

With the increased demand for biobased epoxy thermosets as an alternative to petroleum-based materials in various fields, developing environment-friendly and high-performance natural fiber-biobased epoxy nanocomposites is crucial for industrial applications. Herein, an environment-friendly nanocomposite is reported by introducing cellulose nanofiber (CNF) in situ interaction with lignin-derived vanillin epoxy (VE) monomer and 4, 4´-diaminodiphenyl methane (DDM) hardener that serves as a multifunctional platform. The CNF-VE nanocomposite is fabricated by simply dispersing the CNF suspension to the VE and DDM hardener solution through the in-situ reaction, and its mechanical properties and thermal insulation behavior, wettability, chemical resistance, and optical properties are evaluated with the CNF weight percent variation. The well-dispersed CNF-VE nanocomposite exhibited high tensile strength (∼127.78 ± 3.99 MPa) and strain-at-break (∼16.49 ± 0.61 %), haziness (∼50 %) and UV-shielding properties. The in situ loading of CNF forms covalent crosslinking with the VE and favors improving the mechanical properties along with the homogeneous dispersion of CNF. The CNF-VE nanocomposite also shows lower thermal conductivity (0.26 Wm−1K−1) than glass. The environment-friendly and high-performance nanocomposite provides multiple platforms and can be used for building materials.

Development of antifogging double-layer film using cellulose nanofibers and carboxymethyl chitosan for white Hypsizygus marmoreus preservation

Films with simultaneously excellent mechanical and anti-fog properties are of great importance for food packaging. A novel strategy is described here to prepare long-lasting anti-fog film with antibacterial and antioxidant capabilities via a simple, green approach. The CMC (carboxymethyl chitosan) gel was integrated with CNF/TA (cellulose nanofibers/tannic acid) composite solution based on layer-by-layer assembly to form a membrane with a bilayer structure. The anti-fog performance of the bilayer film could be adjusted by regulating the CNF/TA layer thickness. On the whole, the developed anti-fog film had high mechanical strength and excellent UV shielding properties, as well as good antibacterial and antioxidant properties, and could be non-fogging for a long time under water vapor (40 °C). The effect of double layer anti-fog film (3%CmFT-3) on the fresh-keeping effect of white Hypsizygus marmoreus was compared at room temperature (28 °C) with commercially available anti-fog PVC film. The results showed that the bilayer anti-fog film could effectively prevent the generation of fog, delay the Browning, inhibit mildew, improve the overall acceptability, and effectively extend the shelf life of white Hypsizygus marmoreus. This biomass-based anti-fog film offers great potential for the development of multifunctional green food packaging.

In situ fabrication of photo-responsive PVA composites enabled by doping with coumarin-derived nanoparticles

This research reports the synthesis and characterization of photo-responsive polyvinyl alcohol (PVA) based polymer nanocomposites doped with coumarin-based nanoparticles. The composites were prepared using a one-step, sustainable, and efficient method. The photo-responsive behaviour of the nanocomposites was based on the reversible [2 + 2] cycloadditions of coumarin moieties, which allowed for reversible changes in the material's properties in response to light stimuli. The composites also exhibited excellent UV shielding properties, making them suitable for various applications, including UV-resistant coatings. This study provides a novel approach to developing sustainable, photo-responsive materials for various applications.

An all-natural, bioinspired, biodegradable electrical insulating composite based on lignocellulose and mica tailings

The rapid development of modern electrical engineering puts forward urgent demand for high-performance electrical insulating materials. In this study, inspired by the layered structure of natural nacre, we present a novel biomimetic composite insulating film (referred to as M/C film) that is derived from agricultural waste corncobs and industrial waste mica tailings through a sol-gel-film transformation process. The novel insulating film has excellent tensile strength (94 MPa), high dielectric strength (68 kV mm−1), low dielectric loss, good heat resistance (T0 = 235 °C), and excellent UV shielding properties. Meanwhile, the M/C film presents environmental impacts much lower than those petrochemical-based plastic film as it can be 100 % recycled in a closed-loop recycling process and easily biodegraded in the environment (lignocellulose goes back to the carbon cycle and the mica return to the geological cycle). It is a potential alternative for petrochemical plastics and provides a possible way to utilize agricultural waste and mica tailings.

Development of a glue- and heat- sealable acorn kernel meal/κ-carrageenan composite film with high-haze and UV-shield for packaging grease

Starch and protein-derived films can be used as alternatives to plastics; however, the utilization of starch and proteins to this way might exacerbate the global food shortage. In this study, we used discarded acorns to prepare a glue- and heat-sealable packaging film. We evaluated the mechanical characteristics, thermal stability, transmittance, haze, and antibacterial properties of an acorn kernel meal/κ-carrageenan (AKM/κC) composite film. The results showed that the haze and transmittance decreased from 96.74% to 94.50% and from 3.50% to 2.25%, respectively, when glycerol increased from 30% to 50%. The AKM/κC film had excellent UV shielding properties (transmittance at 380–200 nm was 0). The 45 g-AKM/κC film had a maximum sealing strength of 5.09 ± 0.29 N/15 mm at 0.3 MPa for 1 s (115 °C). Beef tallow packaged in 45 g-AKM/κC exhibited an increased POV from 0.0187 to 0.0336 g/100 g after 75 days, which was lower than that in air (0.5209 g/100 g). Our developed film had high haze and UV shielding performance and can be used as a plastic packaging substitute for fat-rich foods.

Development of polyethylene antifogging and antibacterial packaging films for lettuce preservation

The antifogging and antibacterial films were fabricated by employing low-density polyethylene (LDPE) with addition of nano-ZnO and surfactants (SF) via extrusion casting method. The SEM results showed that SF promoted the dispersion of nano-ZnO in the film. The LDPE films containing both nano-ZnO and SF exhibited excellent UV shielding, antifogging and antibacterial properties. The antifogging duration of films increased with the increase of nano-ZnO. The lettuces packed by the film containing SF could be clearly visible for its antifogging property. It showed the LDPE films added with nano-ZnO could delay quality deterioration of lettuces and the protective effect enhanced with increased nano-ZnO. Comparing the two films that contained same content of nano-ZnO, the film added with SF could maintain better quality for lettuces, which was also personified with better antibacterial activity against E. coli and S. aureus. This antifogging and antibacterial film was expected to be a candidate for the fruit and vegetable preservation.

Multifunctional double-network Ti3C2Tx MXene composite hydrogels for strain sensors with effective electromagnetic interference and UV shielding properties

The advent of hydrogel-based flexible strain sensors has generated enormous research interest due to their outstanding biocompatibility. However, developing hydrogel-based strain sensors with high gauge factor, wide detection range and multifunctional integration is still challenging. Here, a novel multifunctional hydrogel-based strain sensor is composed of two-dimensional transition metal carbides/nitrides (Ti3C2Tx MXene) and Polyacrylamide-co-Poly-N-hydroxyethylene acrylamide/Carboxy Methyl Cellulose-Fe3+ dual network structure (PAAm-PHEMAA/CMC-Fe3+) with multiple hydrogen bonds and coordination interactions. The dual network design endowed the hydrogel-based human motion sensor with fast rebound and high tensile properties, enabling it to exhibit high sensitivity (response time ∼120 ms and gauge factor ∼1.62), and a wide detection range (0–700%), including joint movements as well as more subtle human motions (facial micro-expression changes and speech). More importantly, the hydrogel-based strain sensor exhibited excellent EMI (41 dB, X-band) and UV shielding properties (365 nm, 100%, 0.5 mm) due to the synergy of porous structure, moderate conductivity, and ionic solution environment. Moreover, it demonstrated robust adhesion (29 kPa), high shape adaptability, and self-healing capability. This innovative multi-functional flexible sensor design provides guidance for the development, research and application of high-performance flexible wearable materials.

Using novel polymer microspheres as an efficient UV filter and blue light converter for constructing multifunctional transparent polyvinyl alcohol films

Overexposure to ultraviolet (UV) light can pose a threat to human health and lead to the photodegradation of organic materials, thereby there is great interest in the development of UV-shielding and UV-to-visible light converting materials. In this study, a novel polymer microsphere with both UV-shielding and blue-light-emitting characteristics was fabricated by grafting disodium 4,4′-bis[(4-anilino-6-hydroxyethylamino-1,3,5-triazin-2-yl) amino] stilbene-2,2′-disulphonate (VBL) onto poly (maleic anhydride-co-α-methyl styrene) (PMAS) microspheres via an esterification reaction. The as-prepared PMAS-VBL microspheres were then incorporated into polyvinyl alcohol (PVA) to prepare composite films. The introduction of PMAS-VBL endowed PVA with excellent UV-shielding and fluorescent properties, which are mainly derived from the UV-to-blue light converting ability of VBL. PVA films containing 7 wt% PMAS-VBL microspheres can block almost 100% UV light while the visible light transmittance was maintained at 66.9% and the absolute quantum yield of the films reached up to 74.26%. This work opens up a new pathway for fabricating UV filters and blue light converters, which are very promising for a diversity of UV-shielding and fluorescence-based applications.

Collagen-PVA Films Plasticized with Choline Acetate Ionic Liquid for Sustained Drug Release: UV Shielding, Mechanical, Antioxidant, and Antibacterial Properties.

Collagen and poly(vinyl alcohol) films as topical drug delivery systems were developed by plasticization with glycerol and different concentrations of choline acetate ([Cho]Ac) ionic liquid (IL). The results showed that [Cho]Ac improved the performance of the materials and can serve as an alternative to synthetic plasticizers such as glycerol. Ciprofloxacin (CIP) was used as a model drug to study its release behavior. Ready-to-use films were characterized for their optical opacity, solubility, swelling, mechanical properties, water contact angle, surface morphology, surface roughness, antioxidant, and antimicrobial activities. Moreover, X-ray diffraction and Fourier Transform Infrared (FTIR) studies were carried out for molecular characterization of the films. [Cho]Ac used as a plasticizing agent showed excellent antioxidant properties, mechanical strength, and UV shielding properties. Further, [Cho]Ac improves the roughness and decreases the solubility of films. The in vitro release behavior of CIP was investigated at physiological pH (7.4), and the results showed that CIP was released in a more controlled manner due to the incorporation of [Cho]Ac into the films' matrix, while the films constructed with glycerol exhibited burst release of CIP. Moreover, the films loaded with CIP showed excellent antibacterial activity against Gram-negative (Escherichia coli) as well as Gram-positive (Staphylococcus aureus) bacteria. This study provides insight into the use of choline-based ILs as plasticizing agents for the fabrication of protein-polymer composite films for wound dressing and many other applications.

Facile Fabrication of Superhydrophobic and Flame-Retardant Coatings on Cotton Fabrics.

The hydrophilicity and inherent flammability of cotton textiles severely limit their usage. To solve these drawbacks, a superhydrophobic and flame-retardant (SFR) coating made of chitosan (CH), ammonium polyphosphate (APP), and TiO2-SiO2-HMDS composite was applied to cotton fabric using simple layer-by-layer assembly and dip-coating procedures. First, the fabric was alternately immersed in CH and APP water dispersions, and then immersed in TiO2-SiO2-HMDS composite to form a CH/APP@TiO2-SiO2-HMDS coating on the cotton fabric surface. SEM, EDS, and FTIR were used to analyze the surface morphology, element composition, and functional groups of the cotton fabric, respectively. Vertical burning tests, microscale combustion calorimeter tests, and thermogravimetric analyses were used to evaluate the flammability, combustion behavior, thermal degradation characteristics, and flame-retardant mechanism of this system. When compared to the pristine cotton sample, the deposition of CH and APP enhanced the flame retardancy, residual char, heat release rate, and total heat release of the cotton textiles. The superhydrophobic test results showed that the maximal contact angle of SFR cotton fabric was 153.7°, and possessed excellent superhydrophobicity. Meanwhile, the superhydrophobicity is not lost after 10 laundering cycles or 50 friction cycles. In addition, the UPF value of CH/APP@TiO2-SiO2-HMDS cotton was 825.81, demonstrating excellent UV-shielding properties. Such a durable SFR fabric with a facile fabrication process exhibits potential applications for both oil/water separation and flame retardancy.

Valorization of flavonoid-rich invasive weed-Eupatorium adenophorum in the cleaner production of coloristic and functional wool fabric with a research focus on photofading mechanism

The ecological destructions and economic losses caused by the invasion of Eupatorium adenophorum have been perplexing researchers and governments. The resource utilization of invasive weeds provides an emerging direction for the control and management of Eupatorium adenophorum. The objective of this study is to utilize Eupatorium adenophorum as a cost-effective source of flavonoid compounds for the cleaner production of coloristic and functional wool. First, the extraction, purification, and identification of Eupatorium adenophorum flavonoids (EAFs) were investigated. The crude extraction of EAFs was implemented by using ethanol/water and the highest total flavonoid content of 37.8 mg rutin equivalent/g was obtained. The crude EAFs extract was further purified by using macroporous adsorption resin. The main components of purified EAFs were patuletin and myricetin, identified by FT-IR and liquid chromatography-mass spectrometry (LC-MS). Afterward, the adsorption mechanism and dyeing performance of EAFs on the pre-mordanted wool were studied. Results stated that the adsorption between them belonged to mono-layer adsorption driven by coordination bond, electrovalent bond, and hydrogen bond, which endowed the dyed wool with a good color fastness of rubbing and washing. The building-up property of EAFs on wool fabric was quite acceptable, implying the feasibility of large-scale production. In addition, the dyed wool showed a ultraviolet protection factor value of 345 and a half-life period of 0.89 s (at 65% relative humidity), demonstrating excellent UV-shielding and antistatic properties, respectively. The improved functionalities of dyed wool were owing to the good UV absorption capacity and hygroscopicity of flavonoids. However, such dyed wool suffered from photofading due to the inferior photostability of EAFs. For exploring the photofading mechanism of dyed wool, the photo-degradation pathway of EAFs on the fabric was speculated based on the detection of the photo-degradation products of EAFs by LC-MS. The founding of some colorless hydroxybenzoic acids in the photo-degradation products suggested the occurrence of oxidation and ring-opening of pyranone structure in flavonoids. In general, our work made an attempt to valorize invasive weed in the green dyeing and finishing of wool and provided theoretical support for the development of the light resistance of flavonoid-treated wool.

Bioinspired High-Strength Montmorillonite-Alginate Hybrid Film: The Effect of Different Divalent Metal Cation Crosslinking.

The natural nacre has a regular ordered layered structure of calcium carbonate tablets and ion crosslinking proteins stacked alternately, showing outstanding mechanical properties. Inspired by nacre, we fabricated different divalent metal cation-crosslinked montmorillonite-alginate hybrid films (MMT-ALG-X2+; X2+ = Cu2+, Cd2+, Ba2+, Ca2+, Ni2+, Co2+ or Mn2+). The effect of ionic crosslinking strength and hydrogen bond interaction on the mechanical properties of the nacre-mimetics was studied. With the cations affinities with ALG being increased (Mn2+ < Co2+ = Ni2+ < Ca2+ < Ba2+ < Cd2+ < Cu2+), the tensile strength of nacre-mimetics showed two opposite influence trends: Weak ionic crosslinking (Mn2+, Co2+, Ni2+ and Ca2+) can synergize with hydrogen bonds to greatly increase the tensile properties of the sample; Strong ionic crosslinking (Ba2+, Cd2+, Cu2+) and hydrogen bonding form a competitive relationship, resulting in a rapid decrease in mechanical properties. Mn2+ crosslinking generates optimal strength of 288.0 ± 15.2 MPa with an ultimate strain of 5.35 ± 0.6%, obviously superior to natural nacre (135 MPa and 2%). These excellent mechanical properties arise from the optimum synergy of ion crosslinking and interfacial hydrogen bonds between crosslinked ALG and MMT nanosheets. In addition, these metal ion-crosslinked composite films show different colors, high visible transparency, and excellent UV shielding properties.

UV-shielding and strong poly(vinyl alcohol) composite films reinforced with zinc oxide@polydopamine core-shell nanoparticles

Zinc oxide@polydopamine (ZnO@PDA) core-shell nanoparticles (NPs) were prepared by depositing PDA on the surface of ZnO NPs via the self-polymerization of dopamine (DA) in alkaline solution. It was found that ZnO@PDA exhibits lower photocatalytic activity and higher UV absorbance than pure ZnO. Moreover, ZnO@PDA NPs could be homogenously dispersed in poly(vinyl alcohol) (PVA) matrix and form strong hydrogen bonding interaction with PVA molecular chains. As a result, the prepared PVA/ZnO@PDA composite films display excellent UV-shielding, mechanical and anti-UV aging properties. Particularly, the PVA composite film added with 2.0 wt% ZnO@PDA is able to shield 96.1% UV irradiation (200–400 nm) and exhibits superior tensile strength (66.3 Mpa) than pure PVA film. Moreover, the result of UV aging tests indicate that ZnO@PDA also give a positive effect on the UV stability of PVA matrix, while PVA/ZnO composite film shows serious degradation. This work proposed a facile and rational strategy to design the ZnO-based UV-shielding agent with reduced photocatalytic activity and enhanced UV absorbance, which may provide an inspiration to construct high performance UV-shielding composites.

Mussel-inspired chemistry to design biodegradable food packaging films with antimicrobial properties

Environmental pollution owing to plastic waste is a growing global issue. Packaging materials generate the maximum plastic waste, weighing 141 million tonnes/year. Driven in part by pressure from progressively environmental-conscious consumers, many industries are shifting their means of packing food products to more sustainable options. To promote sustainability, the present work investigates the potential of mussel-inspired polydopamine (pDA) chemistry to develop biodegradable antimicrobial food packaging materials. The food packaging films are designed using unique material combinations including polyvinyl alcohol (PVA), pDA, glycerol, and epsilon-polylysine (εPL). Along with exceptional biodegradability (46% in 1 week), these films demonstrate superb antibacterial activity against both gram-positive and gram-negative bacteria, as well as good thermal and mechanical properties. Additionally, these packaging films display excellent UV shielding properties that can protect the food from UV-induced photodegradation. Overall, this study uncovers numerous novel phenomena of mussel-inspired polydopamine chemistry to address major issues with plastic-based food packaging, such as biodegradability, microbial contamination of food, light-induced food spoilage, and so on.

Carbon dots enhanced gelatin/chitosan bio-nanocomposite packaging film for perishable foods

Carbon dots (CDs) with intriguing fluorescent property, good biocompatibility, high stability, easy interaction with substrates, are burgeoning carbon nanoparticles with large potential in various applications. Incorporating CDs into the polymer matrix is becoming a popular strategy to endow the complex with new functions. Herein, the green-synthesized CDs was integrated into the mixture of gelatin (derived from waste fish scale) and chitosan, and a multifunctional bio-nanocomposite (defined as Gelatin/Chitosan/CDs) film was developed, which showed the excellent antibacterial, antioxidant, pH-sensitivity, UV shielding, and blue-emission properties. The effects of different concentrations of CDs on the physical, mechanical, structural, and functional activity of bio-nanocomposite film were tested. Compared with the Gelatin/Chitosan film, the Gelatin/Chitosan/CDs film with an optimum addition of 20% CDs showed the enhanced antibacterial, antioxidant as well as UV shielding activities. More importantly, it was used as an effective packaging material for fish meat preservation, reducing the loss of nutritional quality consumption, extending the shelf life of food. Besides, the bio-nanocomposite films also possessed the anti-counterfeiting and pH-responsive properties due to the strong fluorescent emission of CDs, and had the great potential in developing the intelligent packaging materials. Our work shed new light on the new application of CDs and the synthesis of bio-nanocomposite film in food industry.

Transparent cellulose/aramid nanofibers films with improved mechanical and ultraviolet shielding performance from waste cotton textiles by in-situ fabrication

Cellulose films with biodegradability and intrinsically antistatic property have many applications. However, conventional cellulose films show poor toughness and UV-shielding property, and the major sources are high-grade cotton linter or wood pulp. Herein, by using low-cost waste cotton textiles as the raw materials, we successfully fabricated transparent cellulose/aramid nanofibers (ANFs) films, in which in-situ retained ANFs had a diameter of 20–30 nm and a length of several micrometers. Because ANFs and cellulose chains formed strong hydrogen bonding interactions, the tensile strength and elongation of the resultant cellulose/ANFs film with 1.0 wt% ANFs could reach 54.4 MPa and 15.8%, respectively, increased by 63.4% and 154% compared to those of pure cellulose film (33.3 MPa and 6.2%). Meanwhile, the cellulose/ANFs films show excellent UV-shielding properties and irradiation stability. Hence, the novel cellulose/ANFs films with improved mechanical and UV-shielding performance were in-situ prepared leading to enhance the valorization of waste cotton textiles.