Abstract:The lack of renewable resources and their inefficient use is a major challenge facing the society. Lignin is a natural biopolymer obtained mainly as a by-product from pulp-and paper-making industry, and is primarily burned to produce energy. However, the interest for using lignin in more advanced applications has increased rapidly. In particular, lignin based nanoparticles could find potential use in functional surface coatings, nanoglues, drug delivery, and microfluidic devices. In this work, a straightforwar… Show more
“…Figueiredo et al [37] used the same method as described above including identical lignin [34]. The dynamic light scattering results revealed an average hydrodynamic radius of 221 ± 10 nm, which is in good agreement with the results obtained by Lievonen et al [34].…”
Section: Production Of Nano-/microsized Lignin Materialssupporting
Lignin is the second most abundant biopolymer after cellulose. It has long been obtained as a by-product of cellulose production in pulp and paper production, but had rather low added-value applications. A changing paper market and the emergence of biorefinery projects should generate vast amounts of lignin with the potential of value addition. Nanomaterials offer unique properties and the preparation of lignin nanoparticles and other nanostructures has therefore gained interest as a promising technique to obtain value-added lignin products. Due to lignin’s high structural and chemical heterogeneity, methods must be adapted to these different types. This review focuses on the ability of different formation methods to cope with the huge variety of lignin types and points out which particle characteristics can be achieved by which method. The current research’s main focus is on pH and solvent-shifting methods where the latter can yield solid and hollow particles. Solvent shifting also showed the capability to cope with different lignin types and solvents and antisolvents, respectively. However, process conditions have to be adapted to every type of lignin and reduction of solvent demand or the integration in a biorefinery process chain must be focused.
“…Figueiredo et al [37] used the same method as described above including identical lignin [34]. The dynamic light scattering results revealed an average hydrodynamic radius of 221 ± 10 nm, which is in good agreement with the results obtained by Lievonen et al [34].…”
Section: Production Of Nano-/microsized Lignin Materialssupporting
Lignin is the second most abundant biopolymer after cellulose. It has long been obtained as a by-product of cellulose production in pulp and paper production, but had rather low added-value applications. A changing paper market and the emergence of biorefinery projects should generate vast amounts of lignin with the potential of value addition. Nanomaterials offer unique properties and the preparation of lignin nanoparticles and other nanostructures has therefore gained interest as a promising technique to obtain value-added lignin products. Due to lignin’s high structural and chemical heterogeneity, methods must be adapted to these different types. This review focuses on the ability of different formation methods to cope with the huge variety of lignin types and points out which particle characteristics can be achieved by which method. The current research’s main focus is on pH and solvent-shifting methods where the latter can yield solid and hollow particles. Solvent shifting also showed the capability to cope with different lignin types and solvents and antisolvents, respectively. However, process conditions have to be adapted to every type of lignin and reduction of solvent demand or the integration in a biorefinery process chain must be focused.
“…1a). The zeta-potential value (also measured by DLS) of the lignin nanoparticle dispersion was −37.5 and −35.8 mV for DLNPs and OLNPs, respectively, which indicated a relative high stability of these two lignin nanoparticles in water [7]. The uniform particle size, regular-sphere structure, and high stability of these two lignin nanoparticles indicated that they might be promising candidates for the production of nanocomposite films with PVA polymer.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.
“…KL obtained from the black liquor in the pulping process differs from native lignin substantially in monomer composition, molar mass, reactivity, and solubility in water and in common solvents . Furthermore, low reactivity, insolubility in water and the presence of aliphatic thiol groups are a major limitation for industrial processing and large‐scale applications, especially to produce hybrid polymer . In this sense, to utilize KL with high efficiency, developing new methods to treat KL is encouraged to increase the reactivity.…”
Section: Introductionmentioning
confidence: 99%
“…In this study, the redox reaction systems are based on an electron transfer from an electron donor (reducing agent) to an electron acceptor (oxidant agent). A number of investigations have been conducted on the incorporation of KL by polymerization of different monomers and initiators, in order to produce new products by free‐radical polymerization . Some authors reported that the lignin accelerates the polymerization rate due to the existence of phenolic groups and other authors reported that the lignin inhibits the polymerization of vinyl monomers due the macromolecular structure of lignin .…”
The focus of this work is to understand the effect of Kraft lignin (KL) treatment with tert‐butyl hydroperoxide (TBHP) and sodium formaldehyde sulfoxylate (SFS) on the properties of the latexes produced by emulsion copolymerization of styrene (Sty) with n‐butyl acrylate (BuA) and methacrylic acid (MAA), with initiator introduced in a shot process. The study intends to understand the effect of KL concentration after peroxide treatment on the properties not only of the latexes, but also on the copolymers themselves. Latexes were characterized in relation to global conversion, average particle size, zeta potential, coagulum concentration, surface tension and latex stability. The polymers were evaluated through molar mass and molar mass distributions, thermogravimetric analysis, and differential scanning calorimetry. The solubility of the KL in water and water/glycol were presented as a function of pH and KL concentration. Stable latexes were produced via emulsion copolymerization with different amounts of KL. The redox initiator system employed in the KL treatment was not efficient to obtain higher conversions. The increase of the KL concentration caused reduction of overall conversion, particle diameter, stability, molar mass and zeta potential. Among the concentrations tested, the greatest concentration of KL, 6.8 wt% relative to the mass of monomer, exhibited the greatest effect on the properties of the latexes and polymers.
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