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Sustainable Surface Engineering of Lignocellulose and Cellulose by Synergistic Combination of Metal‐Free Catalysis and Polyelectrolyte Complexes
Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
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2019 (English)In: Global Challenges, E-ISSN 2056-6646, Vol. 3, article id 1900018Article in journal (Refereed) Published
Abstract [en]

A sustainable strategy for synergistic surface engineering of lignocellulose and cellulose fibers derived from wood by synergistic combination of metal‐free catalysis and renewable polyelectrolyte (PE) complexes is disclosed. The strategy allows for improvement and introduction of important properties such as strength, water resistance, and fluorescence to the renewable fibers and cellulosic materials. For example, the “green” surface engineering significantly increases the strength properties (up to 100% in Z‐strength) of chemi‐thermomechanical pulp (CTMP) and bleached sulphite pulp (BSP)‐derived sheets. Next, performing an organocatalytic silylation with a nontoxic organic acid makes the corresponding lignocellulose and cellulose sheets hydrophobic. A selective color modification of polysaccharides is developed by combining metal‐free catalysis and thiol‐ene click chemistry. Next, fluorescent PE complexes based on cationic starch (CS) and carboxymethylcellulose (CMC) are prepared and used for modification of CTMP or BSP in the presence of a metal‐free catalyst. Laser‐scanning confocal microscopy reveals that the PE‐strength additive is evenly distributed on the CTMP and heterogeneously on the BSP. The fluorescent CS distribution on the CTMP follows the lignin distribution of the lignocellulosic fibers.

Place, publisher, year, edition, pages
2019. Vol. 3, article id 1900018
Keywords [en]
click chemistry, lignocellulose, metal‐free catalysis, selective fluorescent labeling, sustainable polyelectrolyte complex, synergistic surface engineering, water repellent
National Category
Materials Chemistry Organic Chemistry Paper, Pulp and Fiber Technology
Identifiers
URN: urn:nbn:se:miun:diva-37905DOI: 10.1002/gch2.201900018ISI: 000518818400001OAI: oai:DiVA.org:miun-37905DiVA, id: diva2:1375831
Available from: 2019-12-06 Created: 2019-12-06 Last updated: 2021-04-22Bibliographically approved
In thesis
1. Eco-friendly and Catalytic Surface Engineering of Cellulose and Nanocellulose
Open this publication in new window or tab >>Eco-friendly and Catalytic Surface Engineering of Cellulose and Nanocellulose
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The non-stop use of petroleum-based materials such as plastics can generate significant environmental problems, including pollution of the oceans and increased CO2 levels, and cause diseases like cancer due to the starting monomers. Consequently, increased use of sustainable and non-toxic polymers and monomers is required to address these issues. Cellulose, generously supplied by Mother Nature, is the most abundant biopolymer on Earth. Nanocellulose is a sustainable polymer extracted from the cellulose inwood or produced by bacteria and algae. This biodegradable nanomaterialhas recently been receiving intense research attention, since it has great potential for use in a broad range of industrial and biomedical applications. However, it has limitations such as moisture sensitivity and incompatibility with hydrophobic materials due to its hydrophilic nature. Chemical modification is necessary for it to fulfill the requirements for applications that require high moisture resistance and water repellency. Unfortunately, several of the existing methods involve harsh and toxic conditions or reagents. In this thesis, together with my co-workers, I have employed the toolbox of organocatalysis for accomplishing eco-friendly and innovative surface modification of cellulose and nanocellulose. The organocatalysts we usedmost in our research are the naturally abundant and industrially relevantorganic acids tartaric acid and citric acid.

Direct catalytic esterification of cellulose nanocrystal (CNC) with thioglycolicacid was performed either in suspension or on solid surfaces such as films and foams. We found that the reaction was accelerated by tartaric acid but could also be autocatalytic with respect to the thioglycolic acid under certain conditions. The synthesized CNC-SH was further exploited as a heterogeneous reducing agent as well as a handle for further nanocellulose modifications. This was demonstrated by using CNC-SH as a heterogenous reducing agent of Cu(II) to Cu(I), which is essential for allowing the Cu to actas a catalyst for 2,3-dipolar cycloaddition reactions between azides andalkynes. We also showed that the thia-modified CNC could undergo further functionalizing via thiol-ene click chemistry reactions, for example, we attached fluorescent compounds such as TAMRA and quinidine.

Herein we provide a fluorine-free method to prepare superhydrophobic CNC film with excellent water-resistance properties by combining self-assemblyand organocatalysis. Self-assembly of CNC via vacuum filtration resulted in xa film with a specific roughness at the microscale. Next, the catalytic silylation with a variety of alkoxysilanes in the presence of natural organic acids such as tartaric acid and citric acid was performed. The successful implementation of our method resulted in a super-hydrophobic CNC film (water contact angleover 150°) with excellent water-resistance. Thus, the combination of the selfassembly of a rough surface with catalytic surface modification resulted in a phenomenon like the “lotus effect” as exhibited by the leaves of the lotus flower. An investigation of the oxygen permeability of the octadecyltrimethoxysilane-modified CNC film revealed that it significantly decreased at high relative humidity compared with unmodified CNC films.

In this thesis, the fabrication of hydrophobic and functionalized MTM/CNF nanocomposites using organocatalytic surface modification with a large variety of alkoxysilanes is also performed. The surface modifications are mildand the mechanical strength of the Nacre-mimetic nanocomposites is preserved. Elemental mapping analysis revealed that the silane modification occurred predominantly on the surface.

A combination of organocatalyst and biopolyelectrolyte complex was appliedfor surface engineering of chemi-thermomechanical pulp (CTMP) and bleached sulfite pulp (BSP). The reaction was performed using a synergistic combination of an organocatalyst with a polyelectrolyte (PE) complex. Using this method, the strength properties of CTMP and BSP sheets were significantly increased (up to 100% in Z-strength for CTMP). Further investigations of the distribution of the PE complex were then performed using TAMRA and quinidine labeling and confocal laser scanningmicroscopy. This revealed that an even distribution of the cationic starch component of the PE complex had occurred within the CTMP-based paper sheets, which follows its lignin distribution pattern.

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University, 2021. p. 78
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 339
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-41889 (URN)978-91-88947-94-9 (ISBN)
Public defence
2021-05-07, C312, Holmgatan 10, Sundsvall, 10:00 (English)
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Supervisors
Note

Vid tidpunkten för disputationen var följande delarbeten opublicerade: delararbete 2 och 3 manuskript.

At the time of the doctoral defence the following papers were unpublished: paper 2 and 3 manuscripts.

Available from: 2021-04-22 Created: 2021-04-20 Last updated: 2021-04-22Bibliographically approved

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Alimohammadzadeh, RanaOsong, Sinke H.Abbaszad Rafi, AbdolrahimDahlström, ChristinaCordova, Armando

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