Browsing by Author "Kohlhuber, Nadine"

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Study toward a More Reliable Approach to Elucidate the Lignin Structure-Property-Performance Correlation
(2024-01-08) Diment, Daryna; Tkachenko, Oleg; Schlee, Philipp; Kohlhuber, Nadine; Potthast, Antje; Budnyak, Tetyana M.; Rigo, Davide; Balakshin, Mikhail
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The correlation between lignin structure, its properties, and performance is crucial for lignin engineering in high-value products. Currently, a widespread approach is to compare lignins which differ by more than one parameter (i.e., Kraft vs organosolv vs lignosulfonates) in various applications by attributing the changes in their properties/performance specifically to a certain variable (i.e., phenolic −OH groups). Herein, we suggest a novel approach to overcome this issue by changing only one variable at a time while keeping all others constant before investigating the lignin properties/performance. Indulin AT (Ind-AT), a softwood Kraft lignin, was chosen as the model substrate for this study. Selective (analytical) lignin modifications were used to mask/convert specific functionalities, such as aliphatic (AliphOH) including benzylic −OH (BenzOH) and phenolic −OH (PhOH) groups, carboxyl groups (−COOH) and carbonyl groups (CO) via methylation, acetylation, and reduction. The selectivity and completeness of the reactions were verified by comprehensive NMR analysis (31P and 2D HSQC) of the modified preparations together with state-of-the-art molar mass (MM) characterization. Methylene blue (MB) adsorption, antioxidant activity, and glass transition temperature (Tg) were used to demonstrate and compare the properties/performance of the obtained modified lignins. We found that the contribution of different functionalities in the adsorption of MB follows the trend BenzOH > −COOH > AlipOH > PhOH. Noteworthy, benzylic −OH contributes ca. 3 and 2.3 times more than phenolic and aliphatic −OH, respectively. An 11% and 17% increase of Tg was observed with respect to the unmodified Indulin by methylating benzylic −OH groups and through reduction, respectively, while full acetylation/methylation of aliphatic and phenolic −OH groups resulted in lower Tg. nRSI experiments revealed that phenolic −OH play a crucial role in increasing the antioxidant activity of lignin, while both aliphatic −OH groups and −COOHs possess a detrimental effect, most likely due to H-bonding. Overall, for the first time, we provide here a reliable approach for the engineering of lignin-based products in high value applications by disclosing the role of specific lignin functionalities.
Thin multifunctional coatings for textiles based on the layer-by-layer application of polyaromatic hybrid nanoparticles
(2024-08-07) Babaeipour, Sahar; Nousiainen, Paula; Kimiaei, Erfan; Tienaho, Jenni; Kohlhuber, Nadine; Korpinen, Risto; Kaipanen, Kalle; Österberg, Monika
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The textile industry is striving to develop versatile coatings, combining antibacterial, water-repellent, and breathable properties, all while avoiding toxic components. However, the current solutions have unfavorable ecological impacts. Although the use of waxes has offered promise and is an eco-friendly option, there remains a challenge in achieving all the desired properties in a single solution. Here, we employed biobased nanoparticles, produced from natural fatty acid, tall oil fatty acid (TOFA) and lauric acid (La) esterified lignins and waxes, to create multifaceted textile coatings using a layer-by-layer deposition method. Our results reveal that even at nanoscale thickness, the developed coatings enhanced the water contact angle (WCA) of fabrics from 43° to ∼150° while maintaining good breathability (air permeability ranging between 23 and 31 mm/s. Moreover, the coated fabrics maintained excellent hydrophobicity even after two washing cycles. The surface morphology and roughness of the coatings characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed a defect-free and integrated coating layer. Additionally, the polyaromatic molecules integrated into the coatings contributed to the textiles’ antibacterial properties against S. aureus (∼50% inhibition rate) and improved UV-shielding properties, demonstrating the potential for tailored functionality based on specific application requirements. Our systematic correlation of chemical structure and particle properties enabled a comprehensive understanding of their influence on the functionality and performance of coated fabrics. Furthermore, the layer-by-layer method utilizing biobased particles is a simple and efficient method to enhance the performance of cellulose-based materials. This positions the approach as a promising solution for widespread multifunctional textile applications, such as outdoor clothing.
Upgrading AquaSolv Omni (AqSO) biorefinery: access to highly ethoxylated lignins in high yields through reactive extraction (REx)
(2024-01-24) Rigo, Davide; Kohlhuber, Nadine; Fliri, Lukas; Diment, Daryna; Cho, Mijung; Sumerskii, Ivan; Hummel, Michael; Potthast, Antje; Balakshin, Mikhail
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Chemical modification of lignin (i.e., ethoxylation) improves its properties for specific applications. Reactive extraction (REx)—the simultaneous functionalization and extraction of lignin from biomass—is a green, simple, and powerful solution to minimize subsequent steps in biorefinery operations, while upgrading the isolated products (i.e., lignin or lignin-carbohydrate hybrids). In this work, we successfully introduced REx into our recently reported AquaSolv Omni (AqSO) integrated biorefinery. Here, hydrothermally treated wood solids were refluxed with various EtOH : H2O mixtures (70-99 v/v%) in the presence of catalytic amounts of H2SO4 (c = 0.15-1.2 M). The effects of the process variables on the structures and properties of the obtained lignins and residual solids were elucidated by comprehensive NMR analyses (HSQC, quantitative 13C and 31P), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). In addition, we discuss different analytical approaches—NMR vs. chromatographic methods for the quantification of ethoxy groups in lignin. Implementing REx allowed the isolation of ethoxylated lignins in 27-52% yields (based on the initial lignin content) and to tune the degree of substitution (DS) up to 40.8 EtO-groups/100 Ar (based on quantitative 13C NMR)—which is approximately five times higher compared to other established organosolv processes (i.e., Alcell). Moreover, solution state NMR analysis of residual solids after REx showed that ethoxylation also occurs in the cellulose-rich fraction. REx highly ethoxylated lignins produced through a simple and green process enhanced the performance of polyurethane (PU) adhesive formulations compared to formulations using non-ethoxylated lignins.