Excellent UV-shielding Properties Research Articles

Lignin: A Review on Structure, Properties, and Applications as a Light-Colored UV Absorber

Lignin is a promising UV-shielding material to substitute the synthetic absorbers in a composite due to its excellent UV-shielding property. The chromophores group of lignin is responsible for the ...

Excellent UV Resistance of Polylactide by Interfacial Stereocomplexation with Double-Shell-Structured TiO2 Nanohybrids.

The durable application of polylactide (PLA) under atmospheric conditions is restricted by its poor ultraviolet (UV) stability. To improve the UV stability of polymers, titanium dioxide (TiO2) is often used as a UV light capture agent. However, TiO2 is also a photocatalytic agent, with detrimental effects on the polymer properties. To overcome these two conflicting issues, we used the following approach. TiO2 nanoparticles were first coated with silicon dioxide (SiO2) (with a SiO2 shell content of 5.3 wt %). Subsequently, poly(d-lactide) (PDLA) was grafted onto TiO2@SiO2 nanoparticles, approximately 20 wt %, via a ring-opening polymerization of d-lactide to obtain well-designed double-shell TiO2@SiO2-g-PDLA nanohybrids. These double-shell nanoparticles could be well dispersed in a poly(l-lactide) (PLLA) matrix making use of the stereocomplexation between the two enantiomers. In our concept, the inner SiO2 shell on the TiO2 nanoparticles prevents the direct contact between TiO2 and the PLLA matrix and hence considerably restricts the detrimental photocatalytic effect of TiO2 on PLLA degradation. Additionally, the outer PDLA shell facilitates an improved dispersion of these nanohybrid particles by interfacial stereocomplexation with its enantiomer PLLA. As a consequence, the PLLA/TiO2@SiO2-g-PDLA nanocomposites simultaneously possess excellent UV-shielding property, high(er) tensile strength (>60 MPa), and superior UV resistance, for example, the mechanical properties remain at a level of >90% after 72 h of UV irradiation. In our view, this work provides a novel strategy to make advanced PLA nanocomposites with improved mechanical properties and excellent UV resistance, which enables potential application of PLA in more critical areas such as in durable packaging and fiber/textile applications.

Effects of cellulose nanofibrils/graphene oxide hybrid nanofiller in PVA nanocomposites

NCF/GO hybrid nanofillers with excellent UV-shielding properties were prepared by using TEMPO-oxidized nanocellulose fibrils (NCF) and graphene oxide (GO) as raw materials; different mass ratios of NCF to GO (2: 1, 4: 1, 8: 1, and 16: 1) were used. The NCF and GO were then combined and used as a hybrid filler to study the synergistic effects on polyvinyl alcohol (PVA) nanocomposites. With 5% hybrid nanofiller, the UV-shielding performance of the PVA/NCF/GO composite film was higher than 90%. The tensile strength and Young's modulus of the PVA/CG-2 composite film increased by 74.5% and 278.0%, respectively, and the water absorption decreased by 59%. Moreover, the thermal stabilities of the nanocomposites also improved. This synergistic effect improved the performance of the hybrid nanofiller by avoiding the agglomeration of nanofillers in the polymer matrix and improving the homogeneity of the dispersion. The synergistic effect between the fillers provides a new idea for the preparation of novel multifunctional nanocomposites.

Fabrication of polyvinyl alcohol hydrogels with excellent shape memory and ultraviolet-shielding behavior via the introduction of tea polyphenols.

Shape-memory hydrogels are expected to be used not only in an ordinary environment, but also in some special environments, such as under ultraviolet (UV) irradiation. Developing novel shape-memory polyvinyl alcohol (PVA)/tea polyphenol (TP) hydrogels with UV shielding performance is realistically important in application fields. Herein, we designed functional PVA/TP hydrogels with excellent UV-shielding ability and improved the shape memory on hot water stimuli. This study shows that the abundant hydrogen bonds between PVA and TP are the source of shape memory. The PVA hydrogels with 8 wt% TP loading could approximately recover their original shape after deformation when immersed in water at 50 °C for 30 s. Meanwhile, the hydrogels also had excellent UV shielding capacity. After ageing under UV for 16 days, the observed shape of the hydrogel with 8 wt% TP loading retained 74.7% of the original, and the hydrogel could effectively protect the skin of mice from damage under 10 mW cm−2 UV irradiation. With the understanding of the UV-shielding behavior of hydrogels, this study has been able to generate biomedical materials for human skin protection, specifically skin covering the joint areas, where shape memory of the applied materials is essential.

Construction of functional composite films originating from hemicellulose reinforced with poly(vinyl alcohol) and nano-ZnO

The aim of this study is to prepare functional hemicellulose (HC) films with flexibility, thermoplasticity and UV-shielding ability. HC was firstly esterified with vinyl benzoate and then reinforced with poly(vinyl alcohol) (PVA) and nano-zinc oxide (ZnO). After esterification, the solubility of benzoated HC (BH) increased, while the thermal stability decreased. Moreover, esterification could transform HC into crystalline nature and endow HC with tunable transition temperature (Tg). Adding equivalent mass of PVA and 1% ZnO increased the thermal stability of BH/PVA/ZnO films. XRD and DSC analyses showed the new crystalline structure and the decreased Tg of films, probably due to the interactions among BH, PVA and ZnO. From SEM, the cross sections of films were dense, rough, and were connected to form the network structure, promoting the uniform insertion of ZnO into the matrix. The films showed moderate tensile strength and good flexibility with the maximum elongation at break of 87.18%. In addition, the water vapor permeability (WVP) and oxygen permeability (OP) values of BH/PVA/ZnO film were 2.08 × 10−10 g/m s Pa and 0.95 cm3 μm/m2 d kPa, respectively. Moreover, the film with 1% ZnO exhibited excellent UV-shielding properties with the percentage blocking of UV-A and UV-B of 99.34% and 99.99%, respectively.

Preparation and characterization of foamed wheat straw fiber/polypropylene composites based on modified nano-TiO2 particles

The nano-TiO2 modified foamed wheat straw fiber/polypropylene (F-WSFs/PP) hierarchical composites were fabricated by a hot-extrusion process. To improve the dispersion of nano-TiO2 and increase the compatibility between WSFs and PP, the WSFs were immersed in 1–5 wt% unmodified and coupling agents (A171 or KH550)-modified nano-TiO2 suspensions by vacuum pressure. The size, crystallinity and composition of modified nano-TiO2 were analyzed by Laser particle size analyzer (LS), XRD and FT-IR. Moreover, the modification mechanism was clarified to understand interface interaction between WSFs and PP. SEM results showed that nano-TiO2 was deposited on the WSFs surfaces. UV–Vis showed that WSFs treated with modified-TiO2 exhibited excellent UV-shielding properties in the range of 100–200 nm. Mechanical testing indicated that WSFs treated with 4% KH550-modified nano-TiO2 exhibited the highest flexural (29.27 MPa), tensile (14.38 MPa), and impact (4.55 kJ/m2) strengths. Overall, the TiO2-KH550 modified F-WSFs/PP composites excellent UV-shielding properties and mechanical strengths.

Nature-inspired chemistry toward hierarchical superhydrophobic, antibacterial and biocompatible nanofibrous membranes for effective UV-shielding, self-cleaning and oil-water separation

Fabrication of environmental-friendly, low-cost, and free-standing superhydrophobic nanofibrous membranes with additional functionalities such as self-cleaning and UV-shielding properties is highly demanded for oil-water separation. Herein, we describe the preparation of multifunctional superhydrophobic nanofibrous membrane by using a facile and novel nature-inspired method, i.e., plant polyphenol (tannic acid) metal complex is introduced to generate rough hierarchical structures on the surface of an electrospun polyimide (PI) nanofibrous membrane, followed by modification of poly (dimethylsiloxane) (PDMS). Taking an as-prepared tannic acid − Al3+-based superhydrophobic membrane as an example, it not only exhibits anti-impact, low-adhesive and self-cleaning functions, but also presents excellent performance in the separation of various oil-water mixtures. A high flux up to 6935 l m−2 h−1 with a separation efficiency of over 99% and the oil contents in water below 5 ppm is obtained even after repeating use for twenty separation cycles. Additionally, the membrane exhibits excellent UV-shielding property, attributing to the inherent UV-absorbing ability of tannic acid. Furthermore, the membrane also possesses additional properties including antibacterial activity, good biocompatibility, robust mechanical strength, and excellent resistance to various harsh conditions. These attractive properties of the as-prepared membrane make it a promising candidate for potential applications in industrial oil-contaminated water treatments and oil-water separation.

Superhydrophobic and Ultraviolet-Blocking Cotton Fabrics Based on TiO₂/SiO₂ Composite Nanoparticles.

Superhydrophobic and ultraviolet (UV)-blocking cotton fabrics were prepared by the incorporation of TiO2/SiO2 composite nanoparticles followed by hydrophobization with hexadecyltrimethoxysilane (HDTMS). The TiO2/SiO2 composite nanoparticles were synthesized via sol-gel reaction with tetraethyl orthosilicate (TEOS) as the precursor in the presence of TiO2. As for the resulting products, characterization by Fourier-transform infrared spectrometry (FTIR), X-ray diffractometer (XRD) and scanning electron microscope (SEM) were performed respectively. The hydrophobicity measurement and ultraviolet-blocking property measurement showed that the obtained cotton fabric had a water contact angle of 159.3°, a water shedding angle of 8° and a large ultraviolet protection factor (UPF = 115.42) with UVA transmittance of 3.35%. The introduction of TiO2/SiO2 composite nanostructures onto fibers made the textiles rougher, which were highly beneficial to the formation of superhydrophobic surfaces. The high UV absorbance property of TiO2 imparted excellent UV-shielding property to the treated textiles, and effective blocking of the photoactivity of TiO2 by SiO2 resulted in the UV-durability of the superhydrophobicity on the textiles.

Design and Fabrication of a Renewable and Highly Transparent Multilayer Coating on Poly(lactic acid) Film Capable of UV-Shielding and Antifogging

A new and highly transparent multilayer coating on poly(lactic acid) (PLA) film has been designed and constructed based on the layer-by-layer assembly of green and renewable hydroxypropyl methylcellulose (HPMC) and tannic acid (TA). The surface chemical structure, thickness, and morphology analyses of the multilayer coating confirm that HPMC and TA are successfully incorporated based on the hydrogen-bonding interaction. The resultant coated PLA film presents excellent UV-shielding and antifogging properties, which shows strong dependency on the number of assembly cycles. Although the tensile mechanical property of coated PLA film shows a decrease, the thermal property of the PLA substrate remained. This work provides a simple but effective pathway to design and fabricate highly transparent and environmentally friendly coating for the UV-shielding and antifogging applications.

POSS grafted hybrid-fabric composites with a biomimic middle layer for simultaneously improved UV resistance and tribological properties

Poor interfacial adhesion and inferior UV resistance severely inhibit the development of hybrid Meta-aramid/Polytetrafluoroethylene (Nomex/PTFE) fabric composites for distinguished solid self-lubrication materials, especially under high exterior load and long-term UV irradiation conditions. Herein, glycidyl polyhedral oligomeric silesquioxanes (POSS) nanoparticles are covalently grafted onto the hybrid Nomex/PTFE fabric with a polydopamine/polyethylenimine (PDA/PEI) intermediate layer. The microstructure and chemical characteristics of Nomex and PTFE fibers before and after modification are investigated and the results manifest an obvious increase in surface functional groups and roughness, as well as resin compatibility. Tensile and peeling testing results show that the obtained fabric composites, denoted as hybrid-fabric@PDA/PEI-POSS composites, exhibit 24.3% and 46.8% enhancements in tensile and interfacial bonding strength without discernable decrease in pristine hybrid-fabric strength. In addition, the PDA/PEI-POSS hierarchical coating imparts the hybrid-fabric with excellent UV-shielding properties. As a result, the tribological performance of hybrid-fabric@PDA/PEI-POSS composites presents an obvious improvement under high load and UV irradiation conditions.

White-light-emitting lanthanide and lanthanide-iridium doped supramolecular gels: modular luminescence and stimuli-responsive behaviour

Lanthanide-based light-emitting supramolecular thermoreversible metallogels with tunable luminescence by controlling the stoichiometry of L-X/EuIII·L-X/TbIII·L-X or L-X/EuIII·L-X/[IrIII(F2ppy)2(biimid)]PF6.

White light emission and excellent UV shielding observed in free-standing and flexible films of poly(vinylidene fluoride)/zinc oxide nanocomposite

In the present work, we report the excellent UV shielding properties and white light emission observed in free-standing and flexible films of poly(vinylidene fluoride)/zinc oxide (PVDF/ZnO) nanocomposite, obtained by simple solution casting method. These thermally stable nanocomposite films offer ample scope for excellent UV shielding applications. The photoluminescence spectra of these films show white light emission and can be of profound applications in solid state lighting. Simultaneous observation of UV shielding effects and white light emission in free-standing films of polymer nanocomposites has not been reported.

Synergistic effect of functionally active methacrylate polymer and ZnO nanoparticles on optical and dielectric properties

A crucial need to design a functionally active polymer hybrid for the protection of material structure that are exposing to harmful Ultra Violet radiation (UV). In this paper a poly(pyridine-4-yl-methyl) methacrylate ZnO nanocomposite (PPyMMA/ZnO) was developed by in-situ solution polymerization. The X-ray diffraction (XRD) studies confirmed that the nanocomposite is homogeneous with good compatibility between the two counterparts. The morphological variation arises owing to the incorporation of OA-ZnO in the PPyMMA were observed by using electron microscope techniques. The thermal behaviour of PPyMMA and its ZnO nanocomposites were analysed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The dielectric properties of the polymer and its ZnO nanocomposites were studied over a wide range of temperature (30–300 °C) at frequency 100 KHz. An optical study was carried out to test the optical properties of PPyMMA/ZnO (2, 5 and 5%), which reveals that 2% ZnONPs loading exhibits an excellent UV shielding properties.

Formation and Controlled Growth of Bismuth Titanate Phases into Mesoporous Silica Nanoparticles: An Efficient Self-Sealing Nanosystem for UV Filtering in Cosmetic Formulation.

The application of nanosized inorganic UV filters in cosmetic field is limited by their high photocatalytic properties that could induce the degradation or dangerous transformation of the organic molecules in sunscreen formulations. To overcome this problem and simultaneously enlarge the window of filter's absorption, we propose the growth of bismuth titanates BixTiyOz into mesoporous silica nanoparticles (MSN). We investigated the chemical-physical properties by means of XRPD, TEM, UV-vis spectroscopy, N2 physisorption, XPS, and SF-ICP-MS analysis, while the influence on the environment was evaluated through photocatalytic tests. The growing process of this new nanosystem is discussed underlining the key role of the Bi3+ ion that, acting as a low-melting point agent for the silica framework, led to a self-sealing mechanism. The excellent UV shielding properties combined with a radical suppression of the photocatalytic activity make the proposed nanosystem a perfect candidate for the development of the next generation nanomaterials for sunscreen formulations.

High-performance TiO 2 /polyacrylate nanocomposites with enhanced thermal and excellent UV-shielding properties

Abstract High performance TiO 2 /polymer nanocomposites with enhanced thermal and excellent UV-shielding properties have been successfully prepared by means of the anatase TiO 2 nanoparticles homogeneously dispersed in the poly (methyl methacrylate/butyl acrylate/methacrylic acid) [P (MMA/BA/MAA)] matrix via a miniemulsion polymerization process. Highly crystalline TiO 2 nanoparticles with 5–8 nm diameter, were synthesized by a non-aqueous process and then modified with γ-Methacryloxypropyltrimethoxysilane (A174) to improve the compatibility with polymer. FTIR, TGA and dispersity tests in monomers/water verify that the A174 is chemically bonded onto the surface of TiO 2 nanoparticles. TEM, SEM and EDS analyses indicate that the TiO 2 nanoparticles are homogeneously dispersed in the polymer matrix. TGA and DSC studies confirm that the thermal properties of the resultant nanocomposites are significantly enhanced with respect to the neat polymer. UV–vis transmission spectra results reveal that the films with TiO 2 nanoparticles has an excellent UV-shielding property, even at 1.5 wt% TiO 2 nanoparticles loading can almost block the UV light below 350 nm while still having a high visible transparency. Therefore, the resultant nanocomposite films could be used as transparent UV-shielding materials.

Natural dyeing of cotton with Xylocarpus granatum bark extract: Dyeing, fastness, and ultraviolet protection properties

In this research we investigated the dyeing of cotton fabrics with extracts of Xylocarpus granatum, a mangrove plant with a long history of use in leather tanning and textile dyeing. X. granatum bark was extracted and spray-dried, yielding a tannin-rich, reddish-brown powder. This powder proved a suitable colorant for the natural dyeing of cotton with promising color fastness properties to wet treatments (washing, water, sea water, and perspiration), hot pressing, crocking, and light exposure. However, the dye alone produced only weak levels of coloration and therefore metallic salt mordants were employed to improve the color strength, through the formation of insoluble tannate complexes. The resulting fabric K/S values were dependent on the mordant used and exhibited the following trend: ferric sulfate > sodium dichromate > copper sulfate > potassium aluminum sulfate > no mordant, for fabrics exposed to mordants before and after dyeing. Mordanting resulted in slight variations in shade and color fastness. In most cases, the color fastness properties were preserved, except for color fastness to light and hot pressing, for which lowered ratings were found for some mordants. Stiffness and mechanical performance were not greatly affected by dyeing or mordanting, except for sodium dichromate mordanting which significantly stiffened and weakened the fabric. The ultraviolet protection factor (UPF) of all the dyed samples achieved the maximum (50+) level, highlighting the excellent UV shielding properties of the fabric. Overall, X. granatum bark extract is a promising, effective colorant for the natural dyeing of cotton in terms of appearance, fastness, and physical characteristics.

Simultaneous Enhancements of UV-Shielding Properties and Photostability of Poly(vinyl alcohol) via Incorporation of Sepia Eumelanin

Sepia eumelanin (SE), a biomacromolecule, was developed to prepare the excellent UV-shielding polymer material with better photostability. UV–vis transmittance spectra showed that poly(vinyl alcohol) PVA/SE film blocked most ultraviolet light below 300 nm even with a low concentration of SE (0.5 wt %), which still kept its high transparency in the visible spectrum. Rhodamine B photodegradation measurement further confirmed the excellent UV-shielding properties of PVA/SE film. FTIR indicated that the carbonyl absorption bands resulting from phtodegradation for PVA/SE film did not change after UV exposure for 2700 h. The tensile properties of neat PVA were deceased intensely after UV irradiation; however, those of PVA/SE film were reduced a little. Moreover, AFM indicated that the surface roughness of PVA/SE film was much lower than that of a neat PVA one. It could be concluded that SE reduced the PVA degradation rate dramatically, revealing enhanced photostability of PVA/SE film. The mechanism for outstand...

Biomimetic superhydrophobic surfaces by combining mussel-inspired adhesion with lotus-inspired coating

Superhydrophobic surfaces on PET textiles were fabricated by combined bioinspiration from the strong adhesion of marine mussels and the two-scale structure of lotus leaves under mild conditions. Dopamine can spontaneously polymerize in alkaline aqueous solution to form a thin adhesive layer of polydopamine (PDA) wrapping on the micro-scale fibers. The as-formed thin PDA layer worked as a reactive template to generate PDA nanoparticles decorated on the fiber surfaces, imparting the textiles with excellent UV-shielding properties as well as a hierarchical structure similar to the morphology of the lotus leaf. After further modification with perfluorodecyl trichlorosilane, the textiles turned superhydrophobic with a water contact angle higher than 150°. Due to the strong adhesion of PDA to a wide range of materials, the present strategy may be extendable to fabrication of superhydrophobic surfaces on a variety of other substrates.

Carbon quantum dots decorated leaf-like CuO nanosheets and their improved dispersion for an excellent UV-shielding properties in polymer films

Carbon quantum dot decorated leaf-like CuO nanosheets were prepared by a simple method and successfully dispersed in the polymer film to improve UV-shielding properties.

Highly Transparent and Multifunctional Polymer Nanohybrid Film with Superhigh ZnO Content Synthesized by a Bulk Polymerization Method

Highly transparent and multifunctional ZnO/poly(n-butyl methacrylate) (ZnO/PBMA) nanohybrid films with superhigh contents of ZnO nanoparticles (NPs) were synthesized by a bulk polymerization method. The structure; morphology; and optical, mechanical, and thermal properties of the obtained nanohybrid films were studied. ZnO NPs were dispersed uniformly and retained their original size (4–6 nm) in the PBMA matrix without any aggregation. The ZnO/PBMA nanohybrid films allowed more than 90% of visible light at 550 nm to pass and maintained almost the same high transparency as pure PBMA film even when the ZnO NP content was as high as 60 wt %. The nanohybrid films embedded with ZnO NPs exhibited significantly enhanced multifunctional performance, including excellent UV-shielding properties, good thermal stability, high surface hardness, and desired flexibility. In particular, the coefficient of thermal expansion (CTE) of the nanohybrid films clearly decreased to 193 from 325 ppm/K for pure PBMA below the glass transition temperature (Tg) and strikingly decreased from 5378 to 1373 ppm/K after the glass transition. The ZnO/polymer nanohybrids synthesized in this work are promising for the fabrication of optical devices with high transparency, such as flexible displays, optical filters, and flexible solar cells.