| 1. |
- Esakkimuthu, Esakkiammal Sudha, et al.
(författare)
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Elucidating intermolecular forces to improve compatibility of kraft lignin in poly(lactic acid)
- 2024
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Ingår i: Frontiers in Chemistry. - 2296-2646. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Owing to its abundant supply from renewable resources, lignin has emerged as a promising functional filler for the development of sustainable composite materials. However, achieving good interfacial compatibility between lignin and synthetic polymers, particularly poly (lactic acid) (PLA), remains a fundamental challenge. To advance the development of high-performance bio-based composites incorporating lignin and PLA, our study has scrutinized to unravel the nuances of interfacial binding interactions with the lignin and PLA composite system. Molecular level and experimental examinations were employed to decipher fundamental mechanisms governing and demonstrating the interfacial adhesion. We synthesized casted films of lignin/PLA and acetylated lignin/PLA at varying weight percentages of lignin (5%, 10%, and 20%) and comprehensively investigated their physicochemical and mechanical properties. The inclusion of acetylated lignin in the composites resulted in improved mechanical strength and Young’s modulus, while the glass transition temperature and melting point were reduced compared to neat PLA. Systematic variations in these properties revealed distinct compatibility behaviors between unmodified lignin and acetylated lignin when incorporated into PLA. Molecular dynamics (MD) simulation results elucidated that the observed changes in material properties were primarily attributed to the acetylation of lignin. Acetylated lignin exhibited lower Coulombic interaction energy and higher van der Waals forces, indicating a stronger affinity to PLA and a reduced propensity for intermolecular aggregation compared to unmodified lignin. Our findings highlight the critical role of controlling intermolecular interactions and lignin aggregation to develop PLA composites with predictable performance for new applications, such as functional packaging materials.
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| 2. |
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| 3. |
- Liu, Jinrong, 1995-, et al.
(författare)
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Ag-lignin hybrid nanoparticles for high-performance solar absorption in photothermal antibacterial chitosan films
- 2023
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Ingår i: iScience. - 2589-0042. ; 26:10
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Tidskriftsartikel (refereegranskat)abstract
- There is an urgent need for antimicrobial films based on sustainable resources and production methods. In this study, we present a bio-based nanocomposite film composed of chitosan (∼60 wt %), lignin nanoparticles (LNPs, ∼40 wt %), a small amount of glutaraldehyde (1.5 wt %), and a trace level of silver nanoparticles (AgNPs, 0.072 wt %). The uniform dispersion with LNPs prevented aggregation of metallic silver, resulting in small (diameter 3.3 nm) AgNPs. The nanocomposite film absorbs 89% of radiation across the entire solar spectrum and exhibits a remarkable photothermally triggered antibacterial effect, which is further enhanced by the dark color of lignin. Under simulated solar light illumination, the nanocomposite films demonstrated a significant reduction in viable Escherichia coli count compared to control scenarios. The potential applications of these nanocomposites extend to sunlight-activated antimicrobial films and coatings, addressing the growing demand for sustainable and effective antimicrobial materials.
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| 4. |
- Liu, Jinrong, 1995-, et al.
(författare)
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High-yield production of lignin photonic crystals with ethanol and water
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Structural colors in nature have inspired research into engineered photonic materials starting from renewable resources such as lignin extracted from wood and agricultural residues. A notable obstacle in developing lignin-based photonic crystals lies in the use of hazardous organic solvents, giving rise to safety and environmental concerns. Additionally, low product yields hinder scalable production of lignin photonics. Here, we report a highly efficient method for the fabrication of colloidal lignin particles of predicable size for producing photonic crystals using ethanol and water as the sole solvents. We achieved a 78% mass yield of photonic crystals starting from a crude soda lignin, resulting in vibrant colors spanning the entire visible spectrum. Controlling the particle size can be achieved by varying the dilution rate of a lignin ethanol solution with water, enabling the direct generation of colloidal crystals of preferred colors. The new method paves the way for large-scale development of lignin photonics.
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| 5. |
- Liu, Jinrong, 1995-
(författare)
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Lignin nanoparticles for photonic crystals and photothermal films
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The development of sustainable materials from biobased resources is essential due to environmental concerns posed by fossil-based materials. Lignin is a chemically complex biopolymer that exists in woody tissues of vascular plants. Lignin has many useful properties such as antioxidant activity, thermal stability, UV-absorbance, rigidity and so on. However, an inherent challenge of lignin relates to its complex molecular structures and poor solubility in water and common solvents. One strategy to utilize lignin is to fabricate lignin nanoparticles (LNP) that produce colloidally stable dispersions in water. This thesis aims to develop LNP-based materials which can be used in photonic crystals and photothermal films towards energy-efficient functional materials.The first part of the thesis focused on elucidation of the phenomena occurring during centrifugation-assisted assembly of LNP-photonic crystal (L-PC). L-PC with rainbow coloration or separate colors were produced by controlling the polydispersity index (PDI), particle size (150 to 240 nm), and assembly of LNPs. In a follow-up work, an improved method was developed to increase the yield of L-PCs. The effects of factors such as initial lignin concentration, and dilution time on the particle size and PDI of formed LNPs were studied. Empirical models were established to predict the size of LNPs and successfully used to control the resulting color of L-PCs. Moreover, the nanostructure of L-PCs was investigated. To harness lignin’s ability to absorb solar energy (light wavelength: 250–2500 nm), LNP-based composite films and coatings with photothermal performance were developed in the second part of the thesis. LNP-chitosan films and coatings were prepared and applied to indoor heat management. The LNPs content was adjusted from 10 to 40 wt%. By incorporating LNPs, the mechanical strength and photothermal properties of the films were improved compared to the pure chitosan film. Moreover, LNP-silver-chitosan (CC-Ag@LNP) films were prepared by using LNPs as a reducing agent. Silver ions were reduced on the surface of LNPs with UV-light assistance, and the hybrid nanoparticles were used to prepare films by casting. The CC-Ag@LNP films exhibited improved wet-strength and exhibited antibacterial performance against Escherichia coli (sterilization effect > 99.9%).Overall, this thesis contributes to both the fundamental insight in lignin aggregation to colloidal particles and showcases ways to control their assembly and incorporation into macroscopic materials with added functionality.
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| 6. |
- Liu, Jinrong, 1995-, et al.
(författare)
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Photonic crystals with rainbow colors by centrifugation-assisted assembly of colloidal lignin nanoparticles
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Photonic crystals are optical materials that are often fabricated by assembly of particles into periodically arranged structures. However, assembly of lignin nanoparticles has been limited due to lacking methods and incomplete understanding of the interparticle forces and packing mechanisms. Here we show a centrifugation-assisted fabrication of photonic crystals with rainbow structural colors emitted from the structure covering the entire visible spectrum. Our results show that centrifugation is crucial for the formation of lignin photonic crystals, because assembly of lignin nanoparticles without centrifugation assistance leads to the formation of stripe patterns rather than photonic crystals. We further prove that the functions of centrifugation are to classify lignin nanoparticles according to their particle size and produce monodispersed particle layers that display gradient colors from red to violet. The different layers of lignin nanoparticles were assembled in a way that created semi-closed packing structures, which gave rise to coherent scattering. The diameter of the lignin nanoparticles in each color layer is smaller than that predicted by a modified Bragg’s equation. In situ optical microscope images provided additional evidence on the importance of dynamic rearrangement of lignin nanoparticles during their assembly into semi-closed packing structures. The preparation of lignin nanoparticles combined with the methodology for their classification and assembly pave the way for sustainable photonic crystals.
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| 7. |
- Liu, Liyang, 1990-, et al.
(författare)
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Solventless Amination of Lignin and Natural Phenolics using 2-Oxazolidinone
- 2023
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 16:15
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Tidskriftsartikel (refereegranskat)abstract
- Reactive amine compounds are critical for a vast array of useful chemicals in society, yet a limited number of them are derived from renewable resources. This study developed an efficient route to obtain aminated building blocks from phenolic resources derived from nature, such as lignin and tannic acid, for enhancing their utility in applications such as epoxy resins, nylons, polyurethanes, and other polymeric materials. The reaction utilized a carbon storage compound, 2-oxazolidinone as a solvent and as a reagent circumventing the need of hazardous chemistry of conventional amination routes such as those involving formaldehyde. Both free acids and hindered phenolics were readily converted into aminoethyl derivatives resulting in aromatics with primary amine functionality. The aminated compounds, with the potential for enhanced reactivity, can pave the way toward more advanced renewable building blocks.
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| 8. |
- Moreno, Adrian, et al.
(författare)
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Urushi as a Green Component for Thermally Curable Colloidal Lignin Particles and Hydrophobic Coatings
- 2023
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Ingår i: ACS Macro Letters. - 2161-1653. ; 12:6, s. 759-766
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Tidskriftsartikel (refereegranskat)abstract
- Colloidal lignin nanoparticles are promising buildingblocks forsustainable functional materials. However, their instability in organicsolvents and aqueous alkali limits their applicability. Current stabilizationmethods require nonrenewable and toxic reagents or tedious workupprocedures. Here we show a method to prepare hybrid nanoparticlesusing only natural components. Urushi, a form of black oriental lacquer,and lignin are coaggregated to form hybrid particles, with Urushiacting as a sustainable component that stabilizes the particles viahydration barrier effect and thermally triggered internal cross-linking.The weight fractions of the two components can be adjusted to achievethe desired level of stabilization. Hybrid particles with Urushi content>25 wt % undergo interparticle cross-linking that produces multifunctionalhydrophobic protective coatings that improve the water resistanceof wood. This approach provides a sustainable and efficient methodfor stabilizing lignin nanoparticles and opens up neoteric possibilitiesfor the development of lignin-based advanced functional materials.
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| 9. |
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| 10. |
- Morsali, Mohammad, 1992-
(författare)
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Site-specific reactions of softwood kraft lignin for biobased vitrimers and reactive colloidal particles
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lignin, a natural polyphenolic compound of wood, holds promise as a green alternative to fossil resources given the current environmental concerns. However, its complex structure and limited usability have impeded widespread use of lignin in biobased materials. This thesis is focused on employing a series of chemistries and techniques that facilitate lignin utilization in a variety of applications ranging from bulk materials to colloidal particles. Lignin-based vitrimers, developed by a one pot, catalyst-free click addition of poly(ethylene glycol) divinyl ether to softwood kraft lignin and formation of dynamic acetal exchange network showed excellent performance as recoverable adhesives, reaching lab shear strengths of 2.6 MPa and 6.0 MPa for wood and aluminum substrates, respectively. Stabilized lignin nanoparticles synthesized by hydrothermal crosslinking of hydroxymethylated lignin nanoparticles showed an excellent colloidal stability in organic solvents such as ethanol, acetone, dimethylformamide, and tetrahydrofuran, and aqueous media (3 < pH < 12). These stabilized lignin nanoparticles were subjected to direct surface modification in colloidal state to develop aminated pH-responsive particles. Stabilized lignin nanoparticles, preserving redox activity, showed a capacity in reducing silver ions, forming hybrid lignin-silver nanoparticles for applications such as hydrogen peroxide colloidal sensors. Interaction of silver ions and stabilized lignin nanoparticles contributed to the emergence of discrete patterns of silver in lignin nanoparticle embedded hydrogels. The location and distance of the discrete patterns can be modified by altering the particle size and concentration. Furthermore, redox activity of stabilized lignin nanoparticles, hydroxymethylated lignin nanoparticles and unmodified lignin nanoparticles with different particle sizes (90 nm, 150 nm, 640 nm) were studied in charge storage applications in organic poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) electrodes. Non-modified lignin nanoparticles with the diameter of 150 nm showed the best performance overall, with specific capacities of the electrode reaching 42.5 mAh/g at a current density of 1 A/g. These particles were also demonstrated in a Zinc-lignin battery prototype. To further explore and broaden the horizon of lignin applications, propargylated lignin nanoparticles demonstrated light-induced “click” reactions initiated thermally or by Cu (I) or energy-efficient light emitting diodes with 405 nm wavelength. These nanoparticles were further employed to demonstrate the light-triggered reactions with betulin azide in Pickering emulsions, showcasing the versatility of colloidal chemistry of lignin and opportunities for new applications.
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