Projects per year
Abstract
Hydrogels formed by cellulose nanofibers (CNFs) find use in a variety of applications. CNF hydrogels generally stiffen and ultimately flocculate with increasing salt concentrations. While charge repulsion explains the behavior of nanocellulose variants that have been stabilized by charged groups, it has been a puzzle why ions have such a pronounced effect also on CNFs with unmodified surfaces. We studied the effect of ionic solutes on native CNF hydrogels, and found that already at very low concentrations of around 1 mM, ions cause crowding of the hydrogels. The ionic solutes used were NaCl, Na2SO4, NaI, NaSCN, and sodium acetate. For the hydrogels, we used low densities of CNFs which lead to relatively weak gels that were highly sensitive to salts. Screening of the electrical double layer could not explain the results at such low ion concentrations. To understand cellulose-ion interactions, we used computational molecular dynamics simulations. The results provide an explanation by the effect of ions on the structure of the hydration layers of the cellulose. Understanding how and why ions affect the properties of native CNF hydrogels can help in for example manufacture of CNFs and when using CNFs as material components, substrates for enzymes, or as rheology modifiers. Ion-effects on the hydration layer of cellulose may also be important for more fundamental understanding of interfacial interactions of cellulose with water under different conditions. Graphical abstract: [Figure not available: see fulltext.].
Original language | English |
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Pages (from-to) | 6109-6121 |
Number of pages | 13 |
Journal | Cellulose |
Volume | 29 |
Issue number | 11 |
Early online date | 11 Jun 2022 |
DOIs | |
Publication status | Published - Jul 2022 |
MoE publication type | A1 Journal article-refereed |
Keywords
- Cellulose
- Hofmeister series
- Hydration
- Hydrogel
- Nanocellulose
- Nanofibrils
- Salt effect
Fingerprint
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LIBER Linder: Life-like hybrid materials
Linder, M. (Principal investigator)
01/01/2022 → 31/12/2026
Project: RCF Centre of Excellence
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LIBER Sammalkorpi: LIBER Sammalkorpi
Sammalkorpi, M. (Principal investigator)
01/01/2022 → 31/12/2024
Project: RCF Academy Project
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A novel material concept for high strength cellulose composites
Linder, M. (Principal investigator)
01/01/2019 → 31/12/2021
Project: Academy of Finland: Other research funding
Equipment
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Bioeconomy Research Infrastructure
Seppälä, J. (Manager)
School of Chemical EngineeringFacility/equipment: Facility
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Raw Materials Research Infrastructure
Karppinen, M. (Manager)
School of Chemical EngineeringFacility/equipment: Facility