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Experimental and Theoretical Evaluation of the Solubility/Insolubility Spruce Xylan (Arabino Glucuronoxylan)
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Glycoscience. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.ORCID iD: 0000-0003-3572-7798
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2019 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 3, p. 1263-1270Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019. Vol. 20, no 3, p. 1263-1270
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-248093DOI: 10.1021/acs.biomac.8b01686ISI: 000461270500013PubMedID: 30689362Scopus ID: 2-s2.0-85061537168OAI: oai:DiVA.org:kth-248093DiVA, id: diva2:1307896
Note

QC 20190429

Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-05-22Bibliographically approved
In thesis
1. On the Solubility of Wood Hemicelluloses in Water and its Influence on the Adsorption at Cellulose/Water Interfaces
Open this publication in new window or tab >>On the Solubility of Wood Hemicelluloses in Water and its Influence on the Adsorption at Cellulose/Water Interfaces
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Hemicelluloses are a group of natural polysaccharides and one of the main components of wood. The availability and biodegradability of these polymers have created a great interest in developing new bio-based materials or composites from these materials for different end-use purposes. To develop new materials from these polysaccharides with better functionalities, it is essential to understand the fundamental properties of these compounds. The solubility of hemicelluloses is one of these crucial characteristics since the material has to be dissolved in an appropriate solvent if these biopolymers are to be used in, for example, dense and strong films once the solvents are removed. The interaction of these polysaccharides with different solid surfaces is also significantly influenced by their solubility at the surface/water interface and an understanding of this interaction is essential for describing composite formation, since the polysaccharides are most frequently used together with reinforcing materials such as anisotropic cellulose fibers and fibrils.

In the work described in this thesis, a novel methodology has been developed for characterizing in detail the solubility of the extracted and model mannans, arabinoxylans and xyloglucan polysaccharides. Different chemical structural analyses, chromatography, light scattering and microscopy techniques have been applied to achieve an accurate understanding of the solubility of the polysaccharides in aqueous media. A careful study has been performed to isolate and purify softwood polysaccharides, followed by the preparation of model samples to investigate the influence of processing, structural substitutions and molar mass on the solubility. Association and the phase separation of hemicelluloses have been identified in aqueous media despite their clear and transparent appearance to the naked eye.

Natural hemicelluloses are used in combination with cellulose as composite materials both to introduce different functionalities and to utilize the great mechanical properties of cellulose fibrils/fibers. Accordingly, there was a great need to study the influence of the solubility on the interaction and adsorption of these polysaccharides at the cellulose/water interface. The adsorption at the cellulose/water interface was indeed affected by the physicochemical structures and solubility of the polysaccharides, and it has been shown that an increasing molar mass and an increasing polymer concentration lead to formation of associated structures and a phase separation at cellulose model surfaces.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. p. 60
Series
TRITA-CBH-FOU ; 2019:29
Keywords
Wood, Hemicellulose, Solubility, Adsorption, Interaction, Cellulose, Size distribution
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-251110 (URN)978-91-7873-190-9 (ISBN)
Public defence
2019-06-07, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
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Note

QC 2019-05-09

Available from: 2019-05-09 Created: 2019-05-09 Last updated: 2019-05-13Bibliographically approved

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Farahani, Saina KishaniVilaplana, FranciscoWågberg, Lars

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