| 1. |
- Abbadessa, Anna, et al.
(författare)
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Layer-by-layer assembly of sustainable lignin-based coatings for food packaging applications
- 2023
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Ingår i: Progress in organic coatings. - : Elsevier BV. - 0300-9440 .- 1873-331X. ; 182
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Tidskriftsartikel (refereegranskat)abstract
- Packaging plays a critical role in ensuring food safety and shelf life by protecting against e.g., moisture, gases, and light. Polyethylene (PE) is widely used in food packaging, but it is mainly produced from non-renewable resources and it is an inefficient oxygen and light barrier. In this study, the layer-by-layer (LbL) assembly of a sustainably produced lignin-based polymer (EH) with polyethylenimine (PEI) or chitosan (CH) was used to fabricate (partially or fully) bio-based coatings with the aim of improving barrier properties of PE films. The charge density of EH was calculated using a polyelectrolyte titration method and the hydrodynamic diameters of EH, PEI and CH were determined by Dynamic Light Scattering (DLS). LbL assembly was monitored in situ via Quartz Crystal Microbalance with Dissipation (QCM-D) and Stagnation Point Adsorption Reflectometry (SPAR). PE films were coated with a variable number of PEI/EH or CH/EH bilayers (BL) using an immersive LbL assembly method. Coated films were studied in terms of light-blocking ability, wettability, thermal behaviour, surface structure, as well as oxygen and water vapor barrier properties. QCM-D and SPAR data showed a stepwise multilayer formation and strong interactions between the oppositely charged polymers, with PEI/EH coating having a greater amount of deposited polymer compared to CH/EH coating at the same number of BL. Overall, light barrier properties and wettability of the coated films increased with the number of deposited bilayers. Coated PE films maintained the overall thermal behaviour of PE. A number of BL of 20 was found to be the most promising based on the studied properties. Selected samples showed improved oxygen and water vapor barrier properties, with PEI/EH coating performing better than CH/EH coating. Taken altogether, we demonstrated that a novel and sustainable lignin-based polymer can be combined with PEI or CH to fabricate (partially or fully) bio-based coatings for food packaging.
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| 2. |
- Berglund, Jennie, et al.
(författare)
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Acetylation and Sugar Composition Influence the (In)Solubility of Plant beta-Mannans and Their Interaction with Cellulose Surfaces
- 2020
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Ingår i: ACS Sustainable Chemistry and Engineering. - : AMER CHEMICAL SOC. - 2168-0485. ; 8:27, s. 10027-10040
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Tidskriftsartikel (refereegranskat)abstract
- Plant beta-mannans are complex heteropolysaccharides that represent an abundant resource from lignocellulosic biomass. The influence of the molecular motifs of plant mannans on the backbone flexibility, solubility, and the interaction with cellulose was investigated by computational and experimental approaches. The regioselectivity of the acetyl substitutions at C2 and C3 distinctively influenced backbone flexibility in aqueous media, as revealed by molecular dynamic simulations. The molecular weight and degree of acetylation were tailored for two model seed mannans (galactomannan and glucomannan) and compared to spruce acetylated galactoglucomannan. The thermal stability was enhanced with increasing acetyl substitutions, independently of the type of mannan. Dynamic light scattering and atomic force microscopy revealed that the occurrence of galactosylation and a low degree of acetylation (similar to that of native acetylated galactoglucomannans) enhanced solubility/dispersibility of mannans, whereas the solubility/dispersibility decreased for higher degrees of acetylation. Mannan solubility influenced their interactions with cellulose at water-cellulose interfaces in terms of adsorbed mass and viscoelastic properties of the adsorbed mannan layers. Our results reveal that modulating the molecular motifs of plant beta-mannans influences their macromolecular conformation and physicochemical properties, with fundamental implications for their role in the plant cell wall and the design of wood-based materials.
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| 3. |
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| 4. |
- Farahani, Saina Kishani, et al.
(författare)
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Experimental and Theoretical Evaluation of the Solubility/Insolubility of Spruce Xylan (Arabino Glucuronoxylan)
- 2019
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 20:3, s. 1263-1270
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 American Chemical Society. The molecular solubility of softwood arabinoglucuronoxylan (AGX) has been thoroughly investigated, and it has been shown that the chemical and physical structures of the extracted hemicellulose are not significantly influenced by different purification steps, but a transient molecular solubility of AGX was observed in aqueous media at low concentrations (1 g/L) when the dissolved macromolecules had a hydrodynamic diameter of up to 10 nm. A phase separation was detected when the concentration was increased to 15 g/L leading to an association of the smaller molecules into fractal structures with a considerably larger diameter, even though the dispersions were still transparent to ocular inspection. Dynamic Light Scattering and Cryo-Transmission Electron Microscopy showed dimensions in the range of 1000 nm. The phase separation of the sample was further characterized by estimating the χ-interaction parameter of AGX in water using the Flory-Huggins theory, and the results supported that water is a poor solvent for AGX. This behavior is crucial when films and hydrogels based on these biopolymers are made, since the association will dramatically affect barrier and mechanical properties of films made from these materials.
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| 5. |
- Farahani, Saina Kishani, et al.
(författare)
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Influence of Solubility on the Adsorption of Different Xyloglucan Fractions at Cellulose-Water Interfaces
- 2020
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Ingår i: Biomacromolecules. - : AMER CHEMICAL SOC. - 1525-7797 .- 1526-4602. ; 21:2, s. 772-782
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Tidskriftsartikel (refereegranskat)abstract
- Xylogucan (XG) fractions with different molar masses were prepared while preserving the natural structure of the XG. The solubility of the fractions was investigated using light scattering, chromatography, and microscopy techniques. The conformational changes of the XG molecules and their association and phase separation were investigated together with concentration and molar mass changes. The knowledge gained was then applied to investigate the interaction of different XG fractions at cellulose model surfaces using a quartz crystal microbalance with dissipation. The results indicate that there is a cluster formation and phase separation of the XG molecules at the cellulose/water interface induced by the increase in XG concentration close to the surface. Concomitantly, the adsorption regimes are altered for the XG fractions depending on the solubility properties, indicating that the insolubility, association, and phase separation of XGs in aqueous media affect their interaction with cellulose. The study is of vital importance for improving the functionality of sustainable materials made from xyloglucan/cellulose natural composites.
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| 6. |
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| 7. |
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| 8. |
- Farahani, Saina Kishani, et al.
(författare)
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The influence of solubility on the adsorption of different Xyloglucan fractions at Cellulose Water Interfaces
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Xylogucan (XG) fractions with different molar masses were prepared while preserving the natural structure of the XG. The solubility of the fractions was investigated using light- scattering, chromatography and microscopy techniques. The conformational changes of the XG molecules and their association and phase separation were investigated together with concentration and molar mass changes. The knowledge gained was then applied to investigate the interaction of different XG fractions at cellulose model surfaces using a quartz crystal microbalance with dissipation. The results indicate that there is a cluster formation and phase separation of the XG molecules at the cellulose/water interface induced by the increase in XG concentration close to the surface. Concomitantly, the adsorption regimes are altered for the XG fractions depending on the solubility properties, indicating that the insolubility, association and phase separation of XGs in aqueous media affect their interaction with cellulose. The study is of vital importance for improving the functionality of sustainable materials made from xyloglucan/cellulose natural composites.
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