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Sellman, Farhiya AlexORCID iD iconorcid.org/0000-0003-0624-2185
Publications (7 of 7) Show all publications
Östmans, R., Sellman, F. A., Benselfelt, T., Söderberg, D., Wågberg, L. & Rosén, T. (2024). Advanced characterization of nanocelluloses and their dispersions - linked to final material properties.
Open this publication in new window or tab >>Advanced characterization of nanocelluloses and their dispersions - linked to final material properties
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2024 (English)Manuscript (preprint) (Other academic)
National Category
Paper, Pulp and Fiber Technology
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-346026 (URN)
Note

QC 20240514

Available from: 2024-04-29 Created: 2024-04-29 Last updated: 2024-05-14Bibliographically approved
Sellman, F. A. (2024). Characterization and Utilization of Interactions in Wet and Dry Cellulose Nanofibrillar Networks. (Doctoral dissertation). Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>Characterization and Utilization of Interactions in Wet and Dry Cellulose Nanofibrillar Networks
2024 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Expanding our understanding of how cellulose fibers and fibrils interact with water and its effect on their inherent properties is needed to optimize their utilization in the making of novel bio-based materials, but also useful in more traditional products (pulp, paper, and packaging).

The overall objective of the work in this thesis was to deepen the understanding of drying-induced structural changes and cellulose-water interactions using cellulosic model materials. Cellulose nanofibrils (CNFs) were employed as they present a distinct advantage with their defined geometry and controlled surface chemistry compared to macroscopic cellulose fibers.

The first part considers the fundamental interactions of CNFs in contact with water and by water removal, and is devoted to identifying the molecular mechanisms behind the process known as hornification. This was done by studying the exposure of CNF sheets to different heat treatments to establish a connection between their reswelling properties, chemical and structural characteristics, and mechanical behavior. The findings indicate that hornification is governed by non-covalent interactions and that the diffusion of water back into a hornified CNF network is kinetically limited. Furthermore, the influence of fibril aspect ratio and chemical functionality on the mechanical properties of wet fibrillar networks was studied. Fibrils were prepared from fibers with different hemicellulose content. It was found that longer fibrils formed stiffer and more ductile materials, owing to a longer-range and more uniform distribution of stress transfer. Additionally, high aspect ratio fibrils form networks capable of holding larger amounts of water. It was also possible to elucidate the influence of aspect ratio on the network formation, where long and short fibrils form networks with different topologies. These results were integrated into a mechanical network model to present an improved elastoplastic description of the network properties.

The second part of the thesis presents potential applications where control of the water uptake in the fibrillar networks is required. Anisotropic fibrillar hydrogels were prepared to function as actuators and superabsorbents. With the help of the knowledge built in the first part of the work, the water uptake in the fibrillar networks could be maximized. This resulted in CNF hydrogel actuators far surpassing conventional hydrogel used in actuation performance and integration of CNF sheets in a superabsorbent heterostructure, where the most strongly immobilized water can be retained at high pressures. 

Abstract [sv]

Att utvidga vår förståelse för hur cellulosafibrer och fibriller interagerar med vatten och dess effekt på deras inneboende egenskaper är nödvändigt för att optimera deras användning vid tillverkning av nya biobaserade material, men även i traditionella produkter (massa, papper och förpackningar).

Det övergripande målet med arbetet i denna avhandling var att fördjupa förståelsen för strukturella förändringar orsakade av torkning och cellulosa-vatten interaktioner med hjälp av cellulosabaserade modellmaterial. Cellulosa nanofibriller (CNFs) användes då de har en fördel med sin definierade geometri och kontrollerade ytkemi i jämförelse med makroskopiska cellulosafibrer. 

Den första delen avhandlar de grundläggande interaktionerna mellan CNFs i kontakt med vatten och efter vattenborttagning, och ägnas åt att identifiera de molekylära mekanismerna bakom processen som kallas hornifiering. Detta gjordes genom att studera CNF-ark som utsatts för olika värmebehandlingar för att fastställa en koppling mellan deras svällningsegenskaper, kemiska och strukturella egenskaper samt mekaniska beteende. Resultaten indikerar att förhorning styrs av icke-kovalenta interaktioner och att diffusionen av vatten tillbaka in i ett förhornat CNF-nätverk är kinetiskt begränsad. Sedan studerades inflytandet av fibrillernas längd-bredd förhållande och kemisk funktionalitet på de mekaniska egenskaperna hos våta fibrillnätverk. Fibriller framställdes från fibrer med olika hemicellulosahalt. Resultaten visade att längre fibriller bildade styvare och mer töjbara material, tack vare en längre och mer jämn fördelning av belastningsöverföring. Dessutom bildar fibriller med högt längd-bredd förhållande nätverk som kan hålla större mängder vatten. Det var också möjligt att förklara inflytandet av längd-bredd förhållande på nätverksbildningen, där långa och korta fibriller bildar nätverk med olika topologier. Dessa resultat integrerades i en mekanisk nätverksmodell för att presentera en förbättrad elastoplastisk beskrivning av nätverksegenskaperna.

Den andra delen av avhandlingen presenterar potentiella tillämpningar där kontroll av vattenupptaget i fibrillnätverken krävs. Anisotropa fibrillära hydrogeler framställdes för att fungera som aktuatorer och superabsorbenter. Med hjälp av kunskapen som byggts upp i första delen av avhandlingen kunde vattenupptaget i fibrillnätverken maximeras. Detta resulterade i CNF hydrogelaktuatorer som långt överträffade konventionella hydrogeler i aktuatorprestanda, och integration av CNF-ark i en superabsorbent heterostruktur, där det starkast bundna vattnet kan behållas vid höga tryck.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2024. p. 72
Series
TRITA-CBH-FOU ; 2024:21
Keywords
Cellulose nanofibrils, Drying, Swelling, Colloidal interactions, Network structure, Cellulosa nanofibriller, Torkning, Svällning, Kolloidala interaktioner, Nätverksstrukturer
National Category
Paper, Pulp and Fiber Technology
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-346231 (URN)978-91-8040-932-2 (ISBN)
Public defence
2024-06-05, F3, Lindstedtsvägen 26, Stockholm, 13:00 (English)
Opponent
Supervisors
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20240508

Embargo godkänt av skolchef Amelie Eriksson Karlström via e-post 2024-05-08

Available from: 2024-05-08 Created: 2024-05-07 Last updated: 2024-05-08Bibliographically approved
Wang, Z., Heasman, P., Rostami, J., Benselfelt, T., Linares, M., Li, H., . . . Wågberg, L. (2023). Dynamic Networks of Cellulose Nanofibrils Enable Highly Conductive and Strong Polymer Gel Electrolytes for Lithium-Ion Batteries. Advanced Functional Materials, 33(30), Article ID 2212806.
Open this publication in new window or tab >>Dynamic Networks of Cellulose Nanofibrils Enable Highly Conductive and Strong Polymer Gel Electrolytes for Lithium-Ion Batteries
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2023 (English)In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 33, no 30, article id 2212806Article in journal (Refereed) Published
Abstract [en]

Tunable dynamic networks of cellulose nanofibrils (CNFs) are utilized to prepare high-performance polymer gel electrolytes. By swelling an anisotropically dewatered, but never dried, CNF gel in acidic salt solutions, a highly sparse network is constructed with a fraction of CNFs as low as 0.9%, taking advantage of the very high aspect ratio and the ultra-thin thickness of the CNFs (micrometers long and 2–4 nm thick). These CNF networks expose high interfacial areas and can accommodate massive amounts of the ionic conductive liquid polyethylene glycol-based electrolyte into strong homogeneous gel electrolytes. In addition to the reinforced mechanical properties, the presence of the CNFs simultaneously enhances the ionic conductivity due to their excellent strong water-binding capacity according to computational simulations. This strategy renders the electrolyte a room-temperature ionic conductivity of 0.61 ± 0.12 mS cm−1 which is one of the highest among polymer gel electrolytes. The electrolyte shows superior performances as a separator for lithium iron phosphate half-cells in high specific capacity (161 mAh g−1 at 0.1C), excellent rate capability (5C), and cycling stability (94% capacity retention after 300 cycles at 1C) at 60 °C, as well as stable room temperature cycling performance and considerably improved safety compared with commercial liquid electrolyte systems.

Place, publisher, year, edition, pages
Wiley, 2023
Keywords
cellulose nanofibrils, composites, energy storages, lithium-ion batteries, polymer electrolytes
National Category
Materials Chemistry Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-338472 (URN)10.1002/adfm.202212806 (DOI)000973324900001 ()2-s2.0-85152801974 (Scopus ID)
Note

QC 20231115

Available from: 2023-11-15 Created: 2023-11-15 Last updated: 2023-11-15Bibliographically approved
Östmans, R., Cortes Ruiz, M. F., Rostami, J., Sellman, F. A., Wågberg, L., Lindström, S. B. & Benselfelt, T. (2023). Elastoplastic behavior of anisotropic, physically crosslinked hydrogel networks comprising stiff, charged fibrils in an electrolyte. Soft Matter, 19(15), 2792-2800
Open this publication in new window or tab >>Elastoplastic behavior of anisotropic, physically crosslinked hydrogel networks comprising stiff, charged fibrils in an electrolyte
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2023 (English)In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 19, no 15, p. 2792-2800Article in journal (Refereed) Published
Abstract [en]

Fibrillar hydrogels are remarkably stiff, low-density networks that can hold vast amounts of water. These hydrogels can easily be made anisotropic by orienting the fibrils using different methods. Unlike the detailed and established descriptions of polymer gels, there is no coherent theoretical framework describing the elastoplastic behavior of fibrillar gels, especially concerning anisotropy. In this work, the swelling pressures of anisotropic fibrillar hydrogels made from cellulose nanofibrils were measured in the direction perpendicular to the fibril alignment. This experimental data was used to develop a model comprising three mechanical elements representing the network and the osmotic pressure due to non-ionic and ionic surface groups on the fibrils. At low solidity, the stiffness of the hydrogels was dominated by the ionic swelling pressure governed by the osmotic ingress of water. Fibrils with different functionality show the influence of aspect ratio, chemical functionality, and the remaining amount of hemicelluloses. This general model describes physically crosslinked hydrogels comprising fibrils with high flexural rigidity - that is, with a persistence length larger than the mesh size. The experimental technique is a framework to study and understand the importance of fibrillar networks for the evolution of multicellular organisms, like plants, and the influence of different components in plant cell walls.

Place, publisher, year, edition, pages
Royal Society of Chemistry (RSC), 2023
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-330921 (URN)10.1039/d2sm01571d (DOI)000960684700001 ()36992628 (PubMedID)2-s2.0-85152114916 (Scopus ID)
Note

QC 20230704

Available from: 2023-07-04 Created: 2023-07-04 Last updated: 2024-04-29Bibliographically approved
Sellman, F. A., Benselfelt, T., Larsson, P. T. & Wågberg, L. (2023). Hornification of cellulose-rich materials: A kinetically trapped state. Carbohydrate Polymers, 318, Article ID 121132.
Open this publication in new window or tab >>Hornification of cellulose-rich materials: A kinetically trapped state
2023 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 318, article id 121132Article in journal (Refereed) Published
Abstract [en]

The fundamental understanding concerning cellulose-cellulose interactions under wet and dry conditions remains unclear. This is especially true regarding the drying-induced association of cellulose, commonly described as an irreversible phenomenon called hornification. A fundamental understanding of the mechanisms behind hornification would contribute to new drying techniques for cellulose-based materials in the pulp and paper industry while at the same time enhancing material properties and facilitating the recyclability of cellulose-rich materials. In the present work, the irreversible joining of cellulose-rich surfaces has been studied by subjecting cellulose nanofibril (CNF) films to different heat treatments to establish a link between reswelling properties, structural characteristics as well as chemical and mechanical analyses. A heating time/temperature dependence was observed for the reswelling of the CNF films, which is related to the extent of hornification and is different for different chemical compositions of the fibrils. Further, the results indicate that hornification is related to a diffusion process and that the reswellability increases very slowly over long time, indicating that equilibrium is not reached. Hence, hornification is suggested to be a kinetically limited phenomenon governed by non-covalent reversible interactions and a time/temperature dependence on their forming and breaking.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Aggregation, Cellulose nanofibril, Hornification, Kinetics, Swelling
National Category
Materials Chemistry Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-334855 (URN)10.1016/j.carbpol.2023.121132 (DOI)001056626000001 ()37479442 (PubMedID)2-s2.0-85163374088 (Scopus ID)
Note

QC 20230829

Available from: 2023-08-28 Created: 2023-08-28 Last updated: 2024-05-07Bibliographically approved
Rostami, J., Benselfelt, T., Maddalena, L., Avci, C., Sellman, F. A., Ciftci, G. C., . . . Wågberg, L. (2022). Shaping 90 wt% NanoMOFs into Robust Multifunctional Aerogels Using Tailored Bio-Based Nanofibrils. Advanced Materials, 34(38), Article ID 2204800.
Open this publication in new window or tab >>Shaping 90 wt% NanoMOFs into Robust Multifunctional Aerogels Using Tailored Bio-Based Nanofibrils
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2022 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 34, no 38, article id 2204800Article in journal (Refereed) Published
Abstract [en]

Metal–organic frameworks (MOFs) are hybrid porous crystalline networks with tunable chemical and structural properties. However, their excellent potential is limited in practical applications by their hard-to-shape powder form, making it challenging to assemble MOFs into macroscopic composites with mechanical integrity. While a binder matrix enables hybrid materials, such materials have a limited MOF content and thus limited functionality. To overcome this challenge, nanoMOFs are combined with tailored same-charge high-aspect-ratio cellulose nanofibrils (CNFs) to manufacture robust, wet-stable, and multifunctional MOF-based aerogels with 90 wt% nanoMOF loading. The porous aerogel architectures show excellent potential for practical applications such as efficient water purification, CO2 and CH4 gas adsorption and separation, and fire-safe insulation. Moreover, a one-step carbonization process enables these aerogels as effective structural energy-storage electrodes. This work exhibits the unique ability of high-aspect-ratio CNFs to bind large amounts of nanoMOFs in structured materials with outstanding mechanical integrity—a quality that is preserved even after carbonization. The demonstrated process is simple and fully discloses the intrinsic potential of the nanoMOFs, resulting in synergetic properties not found in the components alone, thus paving the way for MOFs in macroscopic multifunctional composites. 

Place, publisher, year, edition, pages
Wiley, 2022
Keywords
aerogels, cellulose nanofibrils, flame retardancy, gas adsorption and separation, metal–organic frameworks, supercapacitors, water purification, Aspect ratio, Carbonization, Crystalline materials, Gas adsorption, Hybrid materials, Nanocellulose, Nanofibers, Supercapacitor, Bio-based, Crystalline networks, Flame-retardancy, Gas adsorption and separations, High aspect ratio, Mechanical integrity, Metalorganic frameworks (MOFs), Nano-fibrils, Binders, Composites, Loading, Materials, Powder, Processes
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-326793 (URN)10.1002/adma.202204800 (DOI)000840897400001 ()35906189 (PubMedID)2-s2.0-85135930335 (Scopus ID)
Note

QC 20230515

Available from: 2023-05-15 Created: 2023-05-15 Last updated: 2024-05-21Bibliographically approved
Sellman, F. A., Rostami, J., Östmans, R., Cortes Ruiz, M. F., Lindström, S. B. & Wågberg, L.Influence of Fibril Aspect Ratio and Chemical Functionality on the Mechanical Properties of Cellulose Nanofibril Materials.
Open this publication in new window or tab >>Influence of Fibril Aspect Ratio and Chemical Functionality on the Mechanical Properties of Cellulose Nanofibril Materials
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(English)Manuscript (preprint) (Other academic)
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-346027 (URN)
Note

QC 20240508

Available from: 2024-04-29 Created: 2024-04-29 Last updated: 2024-05-21Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0624-2185

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