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Sustainable Engineering, Click Chemistry and Catalysis: Modification, Fabrication and Application of Cellulosic Materials
Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Mathematics, and Science Education (2023-).
2025 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Due to challenges such as sustainability and increasing carbon footprint, there is a growing demand to replace fossil-based materials with green sustainable alternatives like cellulosic materials. However, unmodified cellulosic materials often encounter issues like high wettability and low mechanical strength that limit their applicability. To overcome these drawbacks, functionalization and modification are crucial and inevitable. Reported methods often involve toxic/harsh conditions or reagents, and multi-step processes. The focus of this thesis is on the fabrication, functionalization, and modification of cellulosic materials through facile and eco-friendly approaches to enhance their properties and broaden their potential applications.

We started with immobilizing copper nanoparticles on controlled pore glass substrate and used it as a recyclable heterogenous catalyst for the copper-catalyzed alkyne-azide cycloaddition (CuAAC). Focusing on sustainability, we also employed cellulosic materials as catalyst supports. First, cellulose was functionalized using a mild organocatalytic approach. Then, copper or palladium nanoparticles were immobilized onto the functionalized cellulose and used as effective recyclable heterogeneous catalysts in different reactions.

Direct esterification of CNC materials with thioglycolic acid was performed enabling us to introduce thiol groups onto CNC materials. The reaction occurred under mild conditions using natural nontoxic organic acid as an organocatalyst. The method was applied on different CNC materials, producing the corresponding thiol-functionalized CNC materials. The thiol-functionalized CNC was used as a heterogeneous recyclable reducing agent to reduce Cu(II) to Cu(I), which is the active form of copper in CuAAC. The prepared thiol-functionalized CNC materials further functionalized with attaching UV active molecules via thiol-ene click chemistry.

Lactic acid (LA) functionalized CNFs were prepared by using an ecofriendly one-step reaction method in high yields. This was achieved by converting pulp fibers into nanofibrillated cellulose lactate under mild conditions, using LA as both reaction media and catalyst. The process was concurrent and involved an autocatalytic esterification reaction without using metal-based or harsh acid catalysts. Moreover, the LA media were recycled and reused in multiple reaction cycles. 

In the fourth study, strong hydrophobic cellulosic materials were prepared via a facile, scalable and eco-friendly method. The method involves a betulin treatment and hot-pressing processes. First, a water-based betulin formulation was developed and used for the treatment of cellulosic materials. The betulin-treated samples were then hot-pressed. Hot-pressing altered the morphologies and led to dense structures. Moreover, it caused a polymorphic transformation of the betulin particles. Water contact angle and tensile tests revealed that the applied betulin/hot-pressing treatment method noticeably enhanced the samples’ hydrophobicities as well as their tensile strengths. Furthermore, a synergistic effect was noticed between the hot-pressing, betulin treatment, and sulfonation during the pulping process.

Densified and strong large veneers were fabricated via a facile and scalable method. The method involves a combination of chemical modifications of aspen veneers followed by hot-pressing. The study showed that hot-pressing enhanced the tensile strengths. The chemical modifications further improved the efficiency of the hot-pressing, resulting in higher tensile strengths. The chemical modifications changed the wood’s composition promoting wood softening and increasing the bonding. Since the method uses convenient and mild treatments combined with continuous hot-pressing, it enables the processing of large samples. It can also lower time/energy consumption, production costs and the environmental impact.

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University , 2025. , p. 112
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 416
National Category
Chemical Engineering Materials Engineering Chemical Sciences Materials Chemistry Organic Chemistry
Identifiers
URN: urn:nbn:se:miun:diva-53250ISBN: 978-91-89786-87-5 (print)OAI: oai:DiVA.org:miun-53250DiVA, id: diva2:1918402
Public defence
2025-01-23, C312, Holmgatan 10, Sundsvall, 10:00 (English)
Opponent
Supervisors
Note

Vid tidpunkten för disputationen var följande delarbete opublicerat: delarbete 5 (manuskript).

At the time of the doctoral defence the following paper was unpublished: paper 5 (manuscript).

Available from: 2024-12-10 Created: 2024-12-05 Last updated: 2024-12-05Bibliographically approved
List of papers
1. Copper nanoparticles on controlled pore glass (CPG) as highly efficient heterogeneous catalysts for “click reactions”
Open this publication in new window or tab >>Copper nanoparticles on controlled pore glass (CPG) as highly efficient heterogeneous catalysts for “click reactions”
2020 (English)In: Scientific Reports, E-ISSN 2045-2322, Vol. 10, no 1, article id 20547Article in journal (Refereed) Published
Abstract [en]

We herein report that supported copper nanoparticles (CuNPs) on commercially available controlled pore glass (CPG), which exhibit high mechanical, thermal and chemical stability as compared to other silica-based materials, serve as a useful heterogeneous catalyst system for 1,3-dipolar cycloadditions (“click” reactions) between terminal alkynes and organic azides under green chemistry conditions. The supported CuNPs-CPG catalyst exhibited a broad substrate scope and gave the corresponding triazole products in high yields. The CuNPs-CPG catalyst exhibit recyclability and could be reuced multiple times without contaminating the products with Cu. 

National Category
Organic Chemistry
Identifiers
urn:nbn:se:miun:diva-40694 (URN)10.1038/s41598-020-77629-3 (DOI)000596296000034 ()2-s2.0-85096622704 (Scopus ID)
Available from: 2020-12-08 Created: 2020-12-08 Last updated: 2024-12-05
2. Direct Organocatalytic Thioglycolic Acid Esterification of Cellulose Nanocrystals: A simple entry to click chemistry on the surface of nanocellulose
Open this publication in new window or tab >>Direct Organocatalytic Thioglycolic Acid Esterification of Cellulose Nanocrystals: A simple entry to click chemistry on the surface of nanocellulose
Show others...
2022 (English)In: Carbohydrate Polymer Technologies and Applications, ISSN 2666-8939, Vol. 3, article id 100205Article in journal (Refereed) Published
Abstract [en]

The mild and simple direct organocatalytic esterification of cellulose nanocrystals (CNC) and nanocellulose-based materials (e.g. foams and films) with thioglycolic acid (TGA) is disclosed. The transformation gives the corresponding thiol group (-SH) functionalized crystalline nanocellulose (CNC-SH) using simple, naturally occurring, and non-toxic organic acids (e.g. tartaric acid) as catalysts. We also discovered that the direct esterification of cellulose with TGA is autocatalytic (i.e. the TGA is catalyzing its own esterification). The introduction of the -SH functionality at the nanocellulose surface opens up for further selective applications. This was demonstrated by attaching organic catalysts and fluorescent molecules, which are useful as sensors, to the CNC-SH surface by thiol-ene click chemistry. Another application is to use the CNC-SH-based foam as a heterogeneous biomimetic reducing agent, which is stable during multiple recycles, for the copper-catalyzed alkyne-azide 1,3-dipolar cycloaddition (“click” reaction).

Keywords
Cellulose nanocrystals, Thiol-functionalized nanocellulose, Organocatalysis, Heterogeneous catalysis, Direct esterification, Click chemistry
National Category
Natural Sciences Bio Materials
Identifiers
urn:nbn:se:miun:diva-41923 (URN)10.1016/j.carpta.2022.100205 (DOI)000821577600041 ()2-s2.0-85129227500 (Scopus ID)
Available from: 2023-01-01 Created: 2021-04-22 Last updated: 2024-12-05Bibliographically approved
3. A facile route for concurrent fabrication and surface selective functionalization of cellulose nanofibers by lactic acid mediated catalysis
Open this publication in new window or tab >>A facile route for concurrent fabrication and surface selective functionalization of cellulose nanofibers by lactic acid mediated catalysis
Show others...
2023 (English)In: Scientific Reports, E-ISSN 2045-2322, Vol. 13, no 1, article id 14730Article in journal (Refereed) Published
Abstract [en]

Celulose nanofibers are lightweight, recycable, biodegradable, and renewable. Hence, there is a great interest of using them instead of fossil-based components in new materials and biocomposites. In this study, we disclose an environmentally benign (green) one-step reaction approach to fabricate lactic acid ester functionalized cellulose nanofibrils from wood-derived pulp fibers in high yields. This was accomplished by converting wood-derived pulp fibers to nanofibrillated “cellulose lactate” under mild conditions using lactic acid as both the reaction media and catalyst. Thus, in parallel to the cellulose nanofibril production, concurrent lactic acid-catalyzed esterification of lactic acid to the cellulose nanofibers surface occured. The direct lactic acid esterification, which is a surface selective functionalization and reversible (de-attaching the ester groups by cleavage of the ester bonds), of the cellulose nanofibrils was confirmed by low numbers of degree of substitution, and FT-IR analyses. Thus, autocatalytic esterification and cellulose hydrolysis occurred without the need of metal based or a harsh mineral acid catalysts, which has disadvantages such as acid corrosiveness and high recovery cost of acid. Moreover, adding a mineral acid as a co-catalyst significantly decreased the yield of the nanocellulose. The lactic acid media is successfully recycled in multiple reaction cycles producing the corresponding nanocellulose fibers in high yields. The disclosed green cellulose nanofibril production route is industrial relevant and gives direct access to nanocellulose for use in variety of applications such as sustainable filaments, composites, packaging and strengthening of recycled fibers. 

Place, publisher, year, edition, pages
Springer Nature, 2023
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:miun:diva-49330 (URN)10.1038/s41598-023-41989-3 (DOI)37679445 (PubMedID)2-s2.0-85170181889 (Scopus ID)
Available from: 2023-09-19 Created: 2023-09-19 Last updated: 2024-12-05Bibliographically approved
4. Birch-Bark-Inspired Synergistic Fabrication of High-Performance Cellulosic Materials
Open this publication in new window or tab >>Birch-Bark-Inspired Synergistic Fabrication of High-Performance Cellulosic Materials
Show others...
2024 (English)In: ACS Sustainable Resource Management, ISSN 2837-1445, Vol. 1, no 12, p. 2554-2563Article in journal (Refereed) Published
Abstract [en]

There is a growing demand for the utilization of sustainable materials, such as cellulose-based alternatives, over fossil-based materials. However, the inherent drawbacks of cellulosic materials, such as extremely low wet strength and resistance to moisture, need significant improvements. Moreover, several of the commercially available wet-strength chemicals and hydrophobic agents for cellulosic material treatment are toxic or fossil-based (e.g., epichlorohydrin and fluorocarbons). Herein, we present an eco-friendly, high-yield, industrially relevant, and scalable method inspired by birch bark for fabricating hydrophobic and strong cellulosic materials. This was accomplished by combining simple surface modification of cellulosic fibers in water using colloidal particles of betulin, an abundant triterpene extracted from birch bark, with sustainable chemical engineering (e.g., lignin modification and hot-pressing). This led to a transformative process that not only altered the morphology of the cellulosic materials into a more dense and compact structure but also made them hydrophobic (contact angles of up to >130°) with the betulin particles undergoing polymorphic transformations from prismatic crystals (betulin III) to orthorhombic whiskers (betulin I). Significant synergistic effects are observed, resulting in a remarkable increase in wet strength (>1400%) of the produced hydrophobic cellulosic materials.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2024
National Category
Chemical Sciences Materials Chemistry Chemical Engineering Materials Engineering
Identifiers
urn:nbn:se:miun:diva-53239 (URN)10.1021/acssusresmgt.4c00266 (DOI)
Funder
Swedish Research CouncilEuropean CommissionMid Sweden UniversityKnowledge Foundation
Available from: 2024-12-04 Created: 2024-12-04 Last updated: 2025-01-07Bibliographically approved

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Abbaszad Rafi, Abdolrahim

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