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Östmans, R., Benselfelt, T., Erlandsson, J., Rostami, J., Hall, S., Lindström, S. B. & Wågberg, L. (2024). Solidified water at room temperature hosting tailored fluidic channels by using highly anisotropic cellulose nanofibrils. Materials Today Nano, 26, Article ID 100476.
Open this publication in new window or tab >>Solidified water at room temperature hosting tailored fluidic channels by using highly anisotropic cellulose nanofibrils
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2024 (English)In: Materials Today Nano, E-ISSN 2588-8420, Vol. 26, article id 100476Article in journal (Refereed) Published
Abstract [en]

Highly anisotropic cellulose nanofibrils can solidify liquid water, creating self-supporting structures by incorporating a tiny number of fibrils. These fibrillar hydrogels can contain as much as 99.99 wt% water. The structure and mechanical properties of fibrillar networks have so far not been completely understood, nor how they solidify the bulk water at such low particle concentrations. In this work, the mechanical properties of cellulose fibrillar hydrogels in the dilute regime from a wt% perspective have been studied, and an elastoplastic model describing the network structure and its mechanics is presented. A significant insight from this work is that the ability of the fibrils to solidify water is very dependent on particle stiffness and the number of contact points it can form in the network structure. The comparison between the experimental results and the theoretical model shows that the fibrillar networks in the dilute regime form via a non-stochastic process since the fibrils have the time and freedom to find contact points during network formation by translational and rotational diffusion. The formed, dilute fibrillar network deforms by sliding fibril contacts upon straining the network beyond its elastic limit. Our results also show that before macroscopic failure, the fibril contacts are restored once the load is released. The exceptional properties of this solidified water are exploited to host fluidic channels, allowing directed fluid transportation in water. Finally, the microfluidic channels formed in the hydrogels are tailored by the layer-by-layer technique to be interactive against external stimuli, a characteristic envisioned to be useful in biomedical applications.

Place, publisher, year, edition, pages
Elsevier BV, 2024
Keywords
Cellulose nanofibrils, Channels, Colloidal gel, Fibrillar hydrogels, Layer-by-layer, Network model
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-345750 (URN)10.1016/j.mtnano.2024.100476 (DOI)2-s2.0-85189942008 (Scopus ID)
Note

QC 20240424

Available from: 2024-04-18 Created: 2024-04-18 Last updated: 2024-04-29Bibliographically approved
Östmans, R. (2024). The properties of hydrated nanocellulose network structures. (Doctoral dissertation). KTH Royal Institute of Technology
Open this publication in new window or tab >>The properties of hydrated nanocellulose network structures
2024 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Long, slender cellulose nanofibrils (CNF) are unique with their high axial modulus, small diameter, high flexibility, and the possibility of chemical tailoring of, among other things, their surface charge density. The objective of this work has been to elucidate how the hydrogel network properties and how their related deformation mechanisms depend on CNF properties, concentration, and chemical environment. In addition, the influence of CNF characteristics on the formation of the structure and properties of isotropic hydrogels, anisotropic hydrogels, and aerogels has been studied. 

This was done by combining theoretical models describing the CNF network's topology and mechanics with high-resolution experiments to validate the theoretical models. Furthermore, the properties of the fibrils have been characterized in detail and linked to the material properties of materials formed from the fibrils. Finally, the CNF networks in this work have been functionalized in two different ways. In the first case, a flow channel was created within the hydrogel network at extremely low CNF concentrations, that could be surface treated with a Layer-by-layer (LbL) methodology with a consecutive addition of oppositely charged polyelectrolytes/nanoparticles to add new functionalities to the channels. Secondly, wet stable aerogels, prepared at higher concentrations of CNFs, were treated using the LbL methodology to adjust the aerogels' surface structure and surface energy, thereby controlling the liquid spreading rate properties of the formed networks.

The most important findings in this work are that CNF network topology and network mechanics can be described using theoretical, rather non-complicated, elastoplastic models. Furthermore, at lower concentrations of CNFs, the network structure is formed in a more organized way, meaning that the fibrils have the time and freedom to seek their optimal contact points during the network formation from a thermodynamic free energy point of view. It has also been shown that the low-density, wet fibrillar network structures formed by neutralizing the charges of the fibrils deform by sliding in fibril/fibril contacts upon straining the network structure above a critical stress. These fibril/fibril contacts are also shown to be re-established when the stress is released, provided that the networks have not been subjected to a macroscopic collapse. Finally, these cellulose networks show great potential for further functionalization using the LbL modification methodology.

Abstract [sv]

Långa, smala cellulosananofibriller (CNF) är unika med sin höga axiella E-modul, låga diameter, höga flexibilitet och stora möjlighet till kemisk modifiering som bland annat använts för att styra fibrillernas ytladdningstäthet. Syftet med detta arbete har varit att klarlägga hur egenskaperna hos hydrogeler, framställda av nanofibriller, och dess deformationsmekanismer, kan kopplas till olika grundläggande CNF-egenskaper, koncentration och kemisk miljö. Dessutom har vi studerat inverkan av hur CNF-egenskaperna påverkar den bildade nätverksstrukturen och hur de påverkar de slutliga egenskaperna hos isotropa- och anisotropa hydrogeler och aerogeler som formats ifrån de olika fibrillslagen. 

Den strategi som användes, och visade sig mycket framgångsrik, för att nå dessa mål, var att kombinera teoretiska modeller som beskriver CNF-nätverkets topologi och mekanik med specialdesignade experiment för att validera de teoretiska modellerna. Vidare har ett omfattande arbete lagts ned på att karakterisera fibrillernas kemiska, strukturella och morfologiska egenskaper och att koppla dessa till de funktionella materialegenskaperna hos de material som har tillverkats ifrån dessa fibriller. Slutligen har de färdiga CNF-nätverken funktionaliserats på två olika sätt. I det första fallet skapades en stabil flödeskanal i ett hydrogelnätverk, som preparerats vid extremt låg CNF-koncentration, och det visade sig vara möjligt att ytbehandla denna kanal med en lager för lager (LbL) metod där motladdade polyelektrolyter och/eller nanopartiklar användes för att tillföra nya egenskaper till kanalen. I det andra fallet behandlades förtillverkade, våtstabila aerogeler, som preparerats vid högre koncentration av CNF, med en LbL-behandling för att kontrollera ytstruktur och ytkemi hos aerogelerna, och att därigenom kontrollera vätskespridningshastigheten hos nätverken.

De viktigaste resultaten i detta arbete är att CNF-nätverkets topologi och nätverksmekanik kan beskrivas med hjälp av relativt okomplicerade teoretiska elastoplastiska modeller. Vidare, har det varit möjligt att visa att vid lägre CNF koncentrationer så bildas nätverksstrukturen på ett mer organiserat sätt, vilket innebär att fibrillerna har tid och friheten att söka sina kontaktpunkter under nätverksbildningen för att nå en optimal struktur utifrån ett termodynamiskt fritt energiperspektiv. Det har också visats att den våta fibrillära nätverksstrukturen hos hydrogelerna deformeras genom att fibrillkontakterna börjar glida vid en pålagd spänning på nätverksstrukturen som överskrider en viss gränsnivå och att fibrillkontakterna återbildas när den pålagda spänningen tas bort. Detta förutsatt att nätverken inte utsatts för en makroskopisk kollaps. Slutligen har vi lyckats visa hur det är möjligt att funktionalisera både hydrogeler och arogeler med hjälp av den så kallade LbL metoden för att skapa nya egenskaper hos nätverken.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2024. p. 78
Series
TRITA-CBH-FOU ; 2024:18
Keywords
Cellulose nanofibrils, Colloidal interactions, colloidal gels, network structure, fibrillar network models, Cellulosa nanofibriller, Kolloidala interaktioner, Kolloidala geler, nätverksstruktur, fibrillära nätverksmodeller
National Category
Paper, Pulp and Fiber Technology
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-346029 (URN)978-91-8040-919-3 (ISBN)
Public defence
2024-05-24, F3 (Flodis),, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Knut and Alice Wallenberg Foundation
Note

QC 2024-04-30

Embargo godkänt av skolchef Amelie Eriksson Karlström via e-post 2024-04-18.

Available from: 2024-04-30 Created: 2024-04-29 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
Enrico, A., Voulgaris, D., Östmans, R., Sundaravadivel, N., Moutaux, L., Cordier, A., . . . Stemme, G. (2022). 3D Microvascularized Tissue Models by Laser-Based Cavitation Molding of Collagen. Advanced Materials, 34(11)
Open this publication in new window or tab >>3D Microvascularized Tissue Models by Laser-Based Cavitation Molding of Collagen
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2022 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 34, no 11Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Wiley, 2022
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-311485 (URN)10.1002/adma.202109823 (DOI)000751398600001 ()35029309 (PubMedID)2-s2.0-85124472232 (Scopus ID)
Note

QC 20220509

Available from: 2022-04-28 Created: 2022-04-28 Last updated: 2022-06-25Bibliographically approved
Wågberg, L., Granberg, H., Erlandsson, J., Francon, H., Zou, F. & Östmans, R. (2018). Spreading of water in low density nanocellulose networks: From capillaries to specific surface area. Paper presented at 255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, LA. Abstracts of Papers of the American Chemical Society, 255
Open this publication in new window or tab >>Spreading of water in low density nanocellulose networks: From capillaries to specific surface area
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2018 (English)In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-269621 (URN)000435537703022 ()
Conference
255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, LA
Note

QC 20200310

Available from: 2020-03-10 Created: 2020-03-10 Last updated: 2022-06-26Bibliographically 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
Sellman, F. A., Östmans, R., Wågberg, L. & Benselfelt, T.Unparalleled Performance of Uniaxial Nanofibril Hydrogel Actuators by Optimizing Fibril-Network Relationships.
Open this publication in new window or tab >>Unparalleled Performance of Uniaxial Nanofibril Hydrogel Actuators by Optimizing Fibril-Network Relationships
(English)Manuscript (preprint) (Other academic)
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-346227 (URN)
Note

QC 20240508

Available from: 2024-05-07 Created: 2024-05-07 Last updated: 2024-05-08Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0435-1150

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