Abstract: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 … Show more
“…However, this absorption peak became much narrower and also shifted to lower wavenumbers (1560 cm −1 for DLNPs/PVA and 1561 cm −1 for OLNPs/PVA, respectively) when lignin nanoparticles were added, indicating that lignin nanoparticles could stabilize the PVA macromolecular structure through trapping the generated free radicals [15]. The carbon–carbon double bonds in the composite films might be negatively charged by lignin nanoparticles; thus, their FTIR spectra exhibited such a wavenumber shift according to the previous reports [15, 30]. The above analysis suggested that the lignin nanoparticles were able to interact with the PVA macromolecular chains through hydrogen bonding and radical-scavenging reactions.Fig.…”
BackgroundAlthough conversion of low value but high-volume lignin by-product to its usable form is one of the determinant factors for building an economically feasible integrated lignocellulose biorefinery, it has been challenged by its structural complexity and inhomogeneity. We and others have shown that uniform lignin nanoparticles can be produced from a wide range of technical lignins, despite the varied lignocellulosic biomass and the pretreatment methods/conditions applied. This value-added nanostructure lignin enriched with multifunctional groups can be a promising versatile material platform for various downstream utilizations especially in the emerging nanocomposite fields.ResultsInspired by the story of successful production and application of nanocellulose biopolymer, two types of uniform lignin nanoparticles (LNPs) were prepared through self-assembling of deep eutectic solvent (DES) and ethanol-organosolv extracted technical lignins derived from a two-stage fractionation pretreatment approach, respectively. Both LPNs exhibited sphere morphology with unique core–shell nanostructure, where the DES–LNPs showed a more uniform particle size distribution. When incorporated into the traditional polymeric matrix such as poly(vinyl alcohol), these LPN products displayed great potential to formulate a transparent nanocomposite film with additional UV-shielding efficacy (reached ~80% at 400 nm with 4 wt% of LNPs) and antioxidant functionalities (reached ~160 μm mol Trolox g−1 with 4 wt% of LNPs). At the same time, the abundant phenolic hydroxyl groups on the shell of LNPs also provided good interfacial adhesion with PVA matrix through the formation of hydrogen bonding network, which further improved the mechanical and thermal performances of the fabricated LNPs/PVA nanocomposite films.ConclusionsBoth LNPs are excellent candidates for producing multifunctional polymer nanocomposites using facile technical route. The prepared transparent and flexible LNPs/PVA composite films with high UV-shielding efficacy, antioxidant activity, and biocompatibility are promising in the advanced packaging field, which potentially provides an additional high-value lignin product stream to the lignocellulose biorefinery. This study could open the door for the production and application of novel LNPs in the nascent bioeconomy.Graphical abstractLignin nanoparticle for transparent nanocomposite film with UV-shielding efficacy
Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0876-z) contains supplementary material, which is available to authorized users.
“…However, this absorption peak became much narrower and also shifted to lower wavenumbers (1560 cm −1 for DLNPs/PVA and 1561 cm −1 for OLNPs/PVA, respectively) when lignin nanoparticles were added, indicating that lignin nanoparticles could stabilize the PVA macromolecular structure through trapping the generated free radicals [15]. The carbon–carbon double bonds in the composite films might be negatively charged by lignin nanoparticles; thus, their FTIR spectra exhibited such a wavenumber shift according to the previous reports [15, 30]. The above analysis suggested that the lignin nanoparticles were able to interact with the PVA macromolecular chains through hydrogen bonding and radical-scavenging reactions.Fig.…”
BackgroundAlthough conversion of low value but high-volume lignin by-product to its usable form is one of the determinant factors for building an economically feasible integrated lignocellulose biorefinery, it has been challenged by its structural complexity and inhomogeneity. We and others have shown that uniform lignin nanoparticles can be produced from a wide range of technical lignins, despite the varied lignocellulosic biomass and the pretreatment methods/conditions applied. This value-added nanostructure lignin enriched with multifunctional groups can be a promising versatile material platform for various downstream utilizations especially in the emerging nanocomposite fields.ResultsInspired by the story of successful production and application of nanocellulose biopolymer, two types of uniform lignin nanoparticles (LNPs) were prepared through self-assembling of deep eutectic solvent (DES) and ethanol-organosolv extracted technical lignins derived from a two-stage fractionation pretreatment approach, respectively. Both LPNs exhibited sphere morphology with unique core–shell nanostructure, where the DES–LNPs showed a more uniform particle size distribution. When incorporated into the traditional polymeric matrix such as poly(vinyl alcohol), these LPN products displayed great potential to formulate a transparent nanocomposite film with additional UV-shielding efficacy (reached ~80% at 400 nm with 4 wt% of LNPs) and antioxidant functionalities (reached ~160 μm mol Trolox g−1 with 4 wt% of LNPs). At the same time, the abundant phenolic hydroxyl groups on the shell of LNPs also provided good interfacial adhesion with PVA matrix through the formation of hydrogen bonding network, which further improved the mechanical and thermal performances of the fabricated LNPs/PVA nanocomposite films.ConclusionsBoth LNPs are excellent candidates for producing multifunctional polymer nanocomposites using facile technical route. The prepared transparent and flexible LNPs/PVA composite films with high UV-shielding efficacy, antioxidant activity, and biocompatibility are promising in the advanced packaging field, which potentially provides an additional high-value lignin product stream to the lignocellulose biorefinery. This study could open the door for the production and application of novel LNPs in the nascent bioeconomy.Graphical abstractLignin nanoparticle for transparent nanocomposite film with UV-shielding efficacy
Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0876-z) contains supplementary material, which is available to authorized users.
“…UV light is absorbed much, especially for shortwave length ultraviolet light (220–280 nm), which has high energy and damaging; however, visible light is poorly absorbed. The absorption ability is normally related to the organic chromophores in the SE …”
Section: Resultsmentioning
confidence: 99%
“…However, polymeric materials can be seriously damaged by prolonged exposure to ultraviolet (UV) radiation. This is because UV light has short enough wavelengths and high enough energies to break the covalent bonds in these polymers . The UV region of solar light can be divided into three regions: ultraviolet C (UVC) (220–280 nm), ultraviolet B (UVB) (280–320 nm), and ultraviolet A (UVA) (320–400 nm).…”
Section: Introductionmentioning
confidence: 99%
“…Although it is difficult to characterize the fine chemical structures of melanin, we know that there are several functional groups in melanin, such as NH and OH groups . Recently, sepia eumelanin (SE) was used as a UV‐absorber in poly(vinyl alcohol) (PVA) . The obtained nanocomposites have good UV‐shielding properties, but they still have some shortcomings as follows.…”
Section: Introductionmentioning
confidence: 99%
“…Moreover, their heat resistance is not high enough to be used in high‐temperature working environments such as aerospace or military applications. In addition, PVA is a water‐soluble polymer, which makes it very compatible with hydrophilic SE . However, the interactions between SE and some oily polymers are weak, which will result in an uneven dispersion of SE in these oily matrices and overall performance degradation of the corresponding nanocomposites.…”
Novel fluorinated copolyimide/amine‐modified sepia eumelanin (ASE) nanocomposites are successfully fabricated via covalent bonds. To achieve this, the polyimide (PI) is synthesized by random co‐polycondensation. The effects of ASE on the structure and properties of the PI are investigated. A multilinked network is formed with ASE acting junctions in the nanocomposites. The mechanical properties of the PI are significantly improved by the addition of ASE, and the optimal tensile strength and elongation at break are 79.7 MPa and 85.42%, respectively. UV–vis transmittance, methylene blue (MB) photodegradation, and recyclability measurements confirm that the PI/ASE nanocomposites are transparent to visible light at low ASE loadings and show outstanding UV‐shielding properties and lifetimes under intense UV irradiation owing to the synergistic absorption of UV light by the PI matrix and ASE. Furthermore, the PI/ASE nanocomposites have enhanced thermal properties with initial degradation temperatures above 500 °C. These properties endow the nanocomposites with great potential for UV‐shielding in the conditions with high temperature and intense ultraviolet light.
Pure organic room‐temperature phosphorescence (RTP) materials have been widely utilized in security signs, anti‐counterfeiting, data encrypting, and other fields, which have attracted great attention. In the past few years, smart materials with color‐tunable organic RTP materials are reported by many researchers, while the work focused on the color‐tunable polymeric RTP materials is still rare, especially for molecular weight‐dependent polymeric RTP systems. Here, we designed and prepared three molecular weight polymers P1, P2, and P3 by different polymerization reaction times, and found that the fluorescence emissions of these polymer powders are various. Unexpectedly, the molecular weight‐dependent polymeric RTP materials are achieved through doping these polymers into polyacrylonitrile (PAN) matrix, and the International de l'Eclairage was redshift from (0.205,0.257) to (0.503,0.435). This phenomenon is ascribed to the different aggregation states formed by assembly of different molecular weight polymeric chains. Meanwhile, the electrostatic interaction between phosphor and PAN is hardly affected by water. Therefore, advanced information encryption can be achieved by using these polymeric phosphors as anti‐counterfeiting ink.
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