UV Shielding Research Articles

Green synthesized clavate-shaped ZnO modified silk fabric with aging resistance and outstanding antibacterial and UV-shielding properties

Silk, a popular luxury textile with many years of history, is easy to embrittle and adsorb bacteria when stored for a long time or exposed to sunlight, which affects its service life. To improve the silk fabrics with excellent antibacterial activity, washing and aging durability, and UV shielding, multifunctional silk fabrics were designed and fabricated via a green finishing approach. Here, we proposed a simple strategy to fabricate silk fabrics with multi-functions via coating clavate-shaped ZnO nanoparticles (ZF-silk fabrics) by dipping and pressing for cycles. The scanning electron microscope (SEM), fourier transform infrared (FTIR), ultraviolet visible spectrophotometry (UV–Vis), and X-ray diffraction (XRD) were used to analyze the structure and properties of fabricated ZF-silk fabrics. Compared with raw silk fabric, the fabricated ZF-silk fabrics represented excellent UV shielding, good tensile strength, and superior antibacterial activity. Notably, the ZF-silk fabrics had good washing stability and aging resistance. In addition, the ZF-silk fabrics possessed superior antibacterial activity before and after aging treatment (under UV radiation for 72 h). Therefore, the durable and multifunctional ZF-silk fabrics indicate great potential for achieving to realize a long service life of the fabrics.

High toughness, UV & blue light shielding and antibacterial bio-based PEF/TiO2 nanowires composites for packaging application

As a candidate of fossil-based poly(ethylene terephthalate) (PET), bio-based poly(ethylene 2,5-furandicarboxylate) (PEF) that could be converted from renewable resources has attracted attention from academia and industry. Here, we prepare a series of new type of PEF/TiO2 NWs composites from 2,5-furandicarboxylic acid (FDCA), ethylene glycol (EG), titanium dioxide nanowire (TiO2 NWs, diameter∼100 nm, length∼20 µm) and dipentaerythritol (Di-PE) via in-situ polymerization. The TiO2 nanowires (0.5∼10 wt‰ based on PEF) and Di-PE (3 mol‰ based on FDCA) were added as fillers and extenders. TiO2 nanowires were distributed in the PEF uniformly, shown by SEM. Compared with pure PEF, the Tg and thermal stability of all nanocomposites got improved. And the impact strength of nanocomposites could reach 60 kJ/m2 in contrast to brittle pure PEF. The UV-A and blue-light shielding of nanocomposites increased from 53 % to 98 % and 28 % to 86 %, respectively, and the nanocomposites still maintained good gas barrier properties. Moreover, the antibacterial activity of nanocomposites against E. coli had increased to 98 %, better than that of the PEF/Ag NWs composites. By uniaxial pre-stretching, the tensile modulus and the elongation at break were improved obviously, from 1840 MPa to 5466 MPa and 4 % to 54 % respectively with pre-stretching ratio increasing. Compared to the PET/TiO2 NWs composites, the PEF/TiO2 NWs composites shows batter thermal property and mechanical property. The PEF/TiO2 NWs composites exhibit potential foreground in the packaging application.

Characterization of active films of chitosan containing nettle Urtica dioica L. extract: Spectral and water properties, microstructure, and antioxidant activity

Chitosan films enriched with aqueous nettle extract (Urtica dioica L.) were evaluated by measuring their solubility, equilibrium moisture, water vapor permeability, spectral and antioxidant properties, and microstructure. Nettle extract showed a significant effect on the analyzed film properties. The addition of nettle extract manifested a sharp decrease in water vapor permeability, decreasing from 5.64 · 10−11 to 2.22 · 10−11 g/m·s·Pa. The chitosan- nettle extract films exhibited a high free-radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Incorporation of nettle extract into the chitosan matrix was successfully carried out to obtain antioxidant films. The results obtained showed that the incorporation of nettle extract allowed obtaining chitosan films with antioxidant properties, including a total phenolic content up to 1.57 mg GAE/g film. Furthermore, the films with nettle extract boast an UV shielding ability with transmittance values close to zero in the UV region and a water solubility up to 1 %. The inherent biodegradability is also a strong advantage of the developed active films.

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.

Supramolecular cross-linking affords chitin nanofibril nanocomposites with high strength and water resistance

Polysaccharide nanofibrils of chitins or celluloses are emerging biobased building blocks for sustainable, high-performance bioinspired nanocomposites fusing high stiffness, strength, and other functionalities. Owing to their hygroscopicity, a crucial challenge towards real-life applications of these nanocomposites is to maintain their mechanical performances in the humid or even fully swollen conditions. Here, we report water resistant nanocomposites composed of sustainable chitin nanofibrils (ChNFs) and polyvinyl alcohol (PVA) that are physically cross-linked by tannic acid (TA) to enhance and stabilize wet mechanical properties. We demonstrate that the formation of polymer-coated core/shell nanofibrils at the intermediate stage is crucial for the well-defined nanopaper structures after casting. By infiltrating TA, the formation of hydrogen bonding in the PVA matrix and at the ChNF/PVA interface renders the nanocomposites with extremely high strength and stiffness, even under high humidity and swelling conditions. With the increase in the amount of conjugated TA, the Young's modulus and tensile strength of the swollen nanocomposites reach up to 3.0 GPa and 70 MPa, respectively, which are superior to the existing water-borne nanofibils/polymer nanocomposites. Moreover, the nanocomposite films show excellent gas barrier properties at high relative humidity (90%), as well as UV shielding, antibacterial properties and biodegradability, complementing the multifunctional property profile and allowing a transfer into applications as advanced packaging materials.

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.

Multi-functional nanocomposite hydrogels based on assembled catechin-modified TiO2 nanoparticle crosslinker for efficient dye removal from wastewater

The removal of contaminants from wastewater is a crucial step towards achieving sustainable development. Nanocomposite hydrogels have emerged as effective adsorbents; however, their limited elasticity, low light transmission, and insufficient self-healing properties hinder their practical applications. Here, we present durable and self-repairing nanocomposite hydrogels produced by free radical polymerization using an assembled structure of TiO2 and catechin, which acts as a crosslinking agent. This assembly enhances the hydrogel's mechanical properties and provides UV shielding and antioxidant features. This hydrogel, with its well-dispersed TiO2, can be activated by UV light to effectively eliminate heavy metal ions and degrade dye molecules from wastewater. These exceptional qualities demonstrate that the nanocomposite hydrogel based on the TiO2@catechin assembly structure has significant potential for advancing the field of wastewater treatment.

Robust and versatile superhydrophobic cellulose-based composite film with superior UV shielding and heat-barrier performances for sustainable packaging

Replacing single-use plastic delivery bags (SPDBs) with cellulose-based materials is an effective strategy to reduce environmental pollution. However, the inherent hydrophilicity and ultralow mechanical strength of cellulose materials limit its development. In this study, zinc oxide (ZnO)-cellulose composite films were successfully prepared through “two-step strategy” of lotus leaves structure simulation, including deposition of micro-nano ZnO particles and stearic acid (STA) modification. Well-dispersed micro-nano ZnO particles with stick-like structure were anchored in the ZnO-cellulose composite film prepared at 90 °C (CF-90). Due to the special structural design and strong interaction between the cellulose and micro-nano ZnO particles, the CF-90 showed higher mechanical property (a 47.8 % improvement in the tensile strength). Impressively, CF-90 also exhibited great UV shielding properties with larger UPF value of 1603.98 and superhigh heat-barrier performance. Moreover, CF-90 obtained excellent superhydrophobicity with a water contact angle of 163.6° by further modification. Consequently, the versatile cellulose-based material bringing a dawn on application of sustainable packaging materials for express delivery industry.

A new multifunctional flame-retardant coating for cotton fabric to enhance smoke suppression, and UV shielding properties

Turmeric powder (TP) is used in the textile industry as a colouring agent, but its impact on the flammability properties of textiles wasn’t investigated. In this work, new coatings containing TP and TP with melamine polyphosphate (MPP) were utilized to enhance the thermal stability, flame retardancy, colour strength (K/S), and UV-protection factor (UPF) of cotton fabric (CF). Flammability tests indicated that TP alone failed to prevent flame spread in the fabric, and it increased the emission of toxic gases, especially CO and CO2. In contrast, the MPP/TP coating was able to put an end to the spread of a flame in CF, and the samples achieved self-extinction. The value of the limiting oxygen index (LOI) of CF was 18.2%, and it enhanced in MPP/TP containing samples to be 37.8%. K/S and UPF values showed that MPP/TP coatings improved the K/S and UPF values of CF to 2.9 and 290, respectively. Additionally, they lowered the toxic gases produced during CF combustion and the maximum specific optical density (Dsmax) of CF. The new coatings improved the char residue production in treated samples at 750 °C compared to CF, according to the thermogravimetric analysis (TGA) data. Untreated and treated samples' mechanical and physical characteristics were measured and compared. Analysis of smoke toxic gases and inspection of char remained following the smoke density test revealed that MPP/TP coating enhanced the flame retardancy of CF in both the condensed and gas phases.

Simple Non-Equilibrium Atmospheric Plasma Post-Treatment Strategy for Surface Coating of Digital Light Processed 3D-Printed Vanillin-Based Schiff-Base Thermosets.

A simple non-equilibrium atmospheric plasma post-treatment strategy was developed for the surface coating of three-dimensional (3D) structures produced by digital light processing 3D printing. The influence of non-equilibrium atmospheric plasma on the chemical and physical properties of vanillin-derived Schiff-base thermosets and the dip-coating process was investigated and compared to the influence of traditional post-treatment with UV-light. As a comparison, thermosets without post-treatment were also subjected to the coating procedure. The results document that UV post-treatment can induce the completion of the curing of the printed thermosets if complete curing is not reached during printing. Conversely, the plasma post-treatment does not contribute to the curing of the thermoset but causes some opening of the imine bonds and the regeneration of aldehyde functions. As a consequence, no great differences are observed between the not post-treated and plasma post-treated samples in terms of mechanical, thermal, and solvent-resistant properties. In contrast to the UV post-treatment, the plasma post-treatment of the thermosets induces a noticeable increase of the thermoset hydrophilicity ascribed to the reformation of amines on the thermoset surface. The successful coating process and the greatest uniformity of the lignosulfonate coating on the surface of plasma post-treated samples are considered to be due to the presence of these amines and aldehydes. The investigation of the UV shielding properties and antioxidant activities documents the increase of both properties with the increasing amount and uniformity of the formed coating. Interestingly, evident antioxidant properties are also shown by the noncoated thermosets, which are deduced to their chemical structures.

Preparation of multifunctional flame-retardant coating of cotton fabrics for electrical Insulating applications

Cotton fabric (CF) was coated with a new multifunctional flame-retardant system consisting of melamine phosphate (MP) and nickel (II) dimethylglyoxime (NDMG). The new coating was applied to enhance the flame retardancy, antibacterial activity, thermal stability, color strength, UV protection, and electrical properties of CF. The weight percentages of NDMG and MP that led to the maximum improvement in CF properties were identified. According to vertical and horizontal flammability tests, coating the fabric with 29%MP/1%NDMG prevented flame propagation in the samples. Moreover, it increased the limiting oxygen index (LOI) of CF from 17.9% to 36.9%. Thermogravimetric analysis (TGA) data presented that the MP/NDMG coating enhanced the char residue at 750°C. Antimicrobial investigations indicated that the coating 29%MP/1%NDMG reduced the growth of S. aureus and E. coli bacteria. UV shielding and color strength (K/S) results revealed that coated fabrics had excellent UV protection (UPF > 175) and enhanced K/S values. The tensile strength of CF was slightly decreased after the coating process. The dielectric constant (ε`), the dielectric loss (ε``), and AC electrical resistivity ([Formula: see text]) with frequency (10-106 Hz) were also investigated. The electrical resistivity increased significantly after adding MP and NDMG to the CFs. The coated sample (23%MP/7%NDMG) showed the best dielectric properties, with a low dielectric constant of 2.6 and [Formula: see text] of 1.40E+10 Ω.cm at 1000 Hz.

Supramolecular and double network strategy toward strong and antibacterial protein films by introducing waterborne polyurethane and quaternized chitosan

Plant-derived protein composite film is one of the promising substitutes for non-renewable petroleum-based materials. However, its application is greatly limited due to the low mechanical strength and poor antibacterial activity. In this paper, a dual network strategy based on supramolecular chemistry was reported for fabricating a high-strength and antibacterial soybean protein (SP)-based biofilm by incorporating waterborne polyurethane (WP) and quaternized chitosan (QCS). Specifically, castor oil as a renewable plant resource was used for the preparation of functional WP polymer. Based on the synergistic effect of WP network and SP network, the performance of SP-based composite film was significantly enhanced. Compared with the original SP film, the tensile strength and toughness of SP/WP/QCS film were substantially increased by 159% and 531%, respectively. In addition, the composite film showed significantly enhanced water resistance and UV shielding capability. Due to the antibacterial effect of the quaternary ammonium salt component, the SP/WP/QCS composite film exhibited superior antibacterial properties. Therefore, this study provides a feasible strategy for the preparation of high-performance SP-based films, which is expected to be applied in packaging, multifunctional adhesive, and UV-shielding coating.

Waterborne rare earth complexes/polyurethane systems with UV shielding and tunable fluorescence for anti-counterfeiting

Fluorescent polymer materials integrated with rare-earth complexes demonstrate promising multifunctional capabilities. However, their complex synthesis procedures and prohibitive cost currently constrain large-scale utilization. Herein, rare earth complexes Eu(PBA)3Phen and Tb(PBA)3Phen were synthesized by coordinating Eu3+, Tb3+ with p-hydroxybenzoic acid and phenanthroline, which were then physically incorporated into waterborne polyurethane (WPU) to obtain Eu-WPU and Eu/Tb-WPU composites. The as-prepared Eu/Tb-WPU had tunable fluorescence, whose fluorescent colors from green to red were achieved under ultraviolet excitation. Compared to Eu(PBA)3Phen (0.27 ms; 0.22 %), the Eu-WPU exhibited a prolonged fluorescence lifetime(1.08 ms) and high fluorescence quantum yield (10.7 %). In addition, Eu-WPU had a wider UV shielding range of 200–289 nm than WPU (200–222 nm). The prepared Eu/Tb-WPU exhibited rich fluorescent emission colors and can be used for information security encryption. Therefore, these Eu-WPU and Eu/Tb-WPU have good application prospects in ultraviolet shielding and fluorescence anti-counterfeiting.

Photothermal-Driven Polymer for a Smart Window with Adaptive Solar Modulation.

Although the thermochromic smart windows with adjustable sunlight transmittance to achieve energy savings are gradually improving, they are still difficult to use, limited by their unreasonable thermal response temperature, slow switching time, and poor durability. Here, we demonstrate a dual-function hybrid thermoresponsive smart window device (CPH) by trapping the phase-change polyHEA-HDA polymer (HEA = hydroxyethyl acrylate, HDA = hexadecyl acrylate) and polydopamine@CsxWO3 (PDA@CWO) core-shell nanoparticles within glasses. The introduced PDA@CWO nanoparticles substantially increase the energy transformation efficiency of solar energy to heat due to their outstanding photothermal conversion. When the temperature increases above the phase-transition temperature of polyHEA-HDA polymer, the copolymer components in the composite material undergo a reversible crystalline-amorphous transition, which enables the transformation of the whole smart window from transparency to opaque in a low ambient temperature. The light transmittance in the solar range can be dynamically modulated between 54.8 and 22.9% with a low ambient temperature while maintaining acceptable visible light transparency and effective UV shielding. A model house testing proves an indoor temperature cooling of 7.1 °C. This study offers a new approach to designing an energy-saving smart window system with multifunctionality.

Self-healing icephobic coating with UV shielding and removability based on biobased epoxy and reversible disulfide bonds

Icephobic coatings have attracted wide attention due to low energy consumption, low cost, and high efficiency. However, the icephobic coating is vulnerable to external damage due to long-term exposure, which can result in icephobic properties loss and limit its industrial application. Herein, the novel amphiphilic epoxy self-healing icephobic coating was designed by a compound with multiple hydrophilic groups, polydimethylsiloxane (PDMS) with hydrophobic groups and 4, 4′-diaminodiphenyldisulfide (APD) with reversible bonds. Moreover, considering the resource crisis, the biobased epoxy (GTE) was selected as the compound containing hydrophilic groups. In this study, the GTE will form hydrogen bonds with water molecules to achieve an anti-icing effect, while PDMS mainly play a deicing effect due to low surface energy. Due to the reasonable design, the icephobic coating showed good comprehensive icephobic properties: a 12.5-fold increase in icing delay time (802 s) and a 6.6-fold decrease in ice adhesion strength (32.6 kPa) compared with bare aluminum. Furthermore, the crystallization temperature of water was reduced by about 11 °C. More importantly, the APD with reversible disulfide bonds provides the icephobic coating with self-healing performance, removability, and excellent UV shielding performance. The coating provides a new idea for the preparation of sustainable and durable coatings with comprehensive icephobic performance.

Recent Progress in Robust Regenerated Soy Protein Film

AbstractThis review aims to provide a comprehensive overview of the research progress on soy protein (SP) film. SP film has gained significant attention due to its natural, renewable, and biodegradable characteristics. The review begins by introducing the film formation mechanisms and preparation methods of SP film, including solution casting, dry‐film formation, and other techniques, and discusses the associated preparation conditions and processes. Subsequently, the review explores the structural features, plasticization modifications, mechanical properties, antimicrobial modifications, UV shielding properties, and conductivity of SP film. Lastly, the review summarizes the current challenges and development directions in SP film research. This includes improving the mechanical performance and stability of the film, exploring novel functionalization approaches, and enhancing the sustainability of the film. Through this review of SP film, the study aims to enhance the understanding of their potential in materials science and various applications while providing guidance and insights for future research and applications.

Transparent chitosan/hexagonal boron nitride nanosheets composite films with enhanced UV shielding and gas barrier properties

It is of great significance to develop natural renewable polymer materials for different applications. Herein, the nano-sized hexagonal boron nitride nanosheets (hBNNSs) were facilely exfoliated through liquid-nitrogen, microwave, and ultrasonication treatments, and novel chitosan/hBNNSs (CS/hBNNSs) films were fabricated via solution casting. The obtained transparent CS/hBNNSs films demonstrated outstanding UV shielding ability with 98.51 % UV-A and 96.40 % UV-B lights being resisted. Compared to those properties of CS film, the oxygen permeability (OP) and carbon dioxide permeability (CO2P) of CS/hBNNSs films are significantly lowered by 96.35 % and 94.06 %, respectively, which are much better than CS/graphene oxide or other CS nanocomposite films. Moreover, the addition of hBNNSs in CS films also obviously improves their water vapor barrier ability, thermostability, mechanical properties, and antibacterial activity. The CS/hBNNSs films and the strategy developed in this work prove their great prospect in producing high-performance packaging films with desirable excellent UV shielding and oxygen barrier qualities.

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.

Incorporation of Bayberry Tannin into a Locust Bean Gum/Carboxycellulose Nanocrystals/ZnO Coating: Properties and Its Application in Banana Preservation.

The application of polysaccharide-based coatings to prolong the shelf-life of fruits has attracted increasing attention. This study aims to develop a fruit coating comprising locust bean gum/carboxycellulose nanocrystals/ZnO (LCZ) blended with bayberry tannins (BT). The results revealed a significant increase from 4.89% and 11.04% to 29.92% and 45.01% in the free radical scavenging rates of 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-di-[3-ethylbenzthiazthiazoline sulfonate] with the percentage of BT increasing from 0% to 5%, respectively. At a 5% of BT, the antibacterial activity against both E.coli and S. aureus exceeded 90% while simultaneously achieving excellent UV shielding (transmittance of 380-200 nm ≤ 0.19%). After 3 days of storage, uncoated bananas showed signs of browning, and their titratable acid and vitamin C (Vc) contents decreased from 0.57% to 0.30% and from 7.37 mg/100 g to 4.77 mg/100 g, respectively. However, bananas coated with LCZ containing 3% BT not only exhibited a better appearance, but also possessed higher titratable acid (0.44%) and Vc content (5.31 mg/100 g). This study provides a sustainable and multifunctional coating for fruit preservation.

Lignin micro/nanoparticles: synthesis, properties, and application to endow polyvinyl alcohol film with multi-functionality

Lignin, as an abundant natural polymer, has great potential in the synthesis of multifunctional micro/nanoparticles. However, the synthesis methods and parameters during the preparation process impact the controllability of lignin micro/nanoparticles (LMNPs), thereby affecting the performance of composite materials containing LMNPs. In this study, a green, simple, and applicable method for organosolv lignin was proposed for the synthesis of LMNPs using recyclable γ-valerolactone and the parameters (lignin concentration, stirring speed, dropping speed, water/solvent ratio, and lignin structure) were systematically investigated. The tuning of multiple properties of the composites was investigated by mixing LMNPs with polyvinyl alcohol (PVA). Results indicated that synthesis parameters affected the LMNPs formation, leading to aggregation/fusion of LMNPs. The obtained spherical LMNPs were electrostatically stable in pH 4–12, uniform (0.09 PDI), and excellent in thermal stability and antioxidant activity. Based on diffusion-restricted cluster–cluster aggregation, LMNPs around 157–442 nm were fabricated through π-π interactions. The PVA/LMNPs composite films showed excellent properties in terms of mechanical properties, thermal stability, UV shielding capacity, and hydrophobicity. The LMNPs with different structures improved the properties of polyvinyl alcohol films, providing a controllable approach for the development of biodegradable food/medical packaging materials and UV-shielding biomaterials.