Strain Stiffening and Negative Normal Force of Agarose Hydrogels
No Thumbnail Available
Access rights
openAccess
Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This publication is imported from Aalto University research portal.
View publication in the Research portal
View/Open full text file from the Research portal
Other link related to publication
View publication in the Research portal
View/Open full text file from the Research portal
Other link related to publication
Date
2020-11-24
Department
Major/Subject
Mcode
Degree programme
Language
en
Pages
Series
Macromolecules
Abstract
Inspired by the specific strain stiffening and negative normal force phenomena in several biological networks, herein, we show strain stiffening and negative normal force in agarose hydrogels. We use both pre-strain and strain amplitude sweep protocols in dynamic rheological measurements where the gel slip was suppressed by the in situ gelation in the cross-hatched parallel plate rheometer geometry. Within the stiffening region, we show the scaling relation for the differential modulus K ∝ σ1, where σ is stress. The strain at the onset of stiffening is almost constant throughout the concentration range. The gels show negative apparent normal stress difference when sheared as a result of the gel contraction. The pore size of the hydrogel is large enough to allow water to move with respect to the network to balance the pressure difference caused by the hoop stress. The rheological analysis together with scanning electron microscopy suggests that the agarose gels can be described using subisostatic athermal network models where the connectivity dictates the stiffening behavior. Therefore, the simple agarose gels appear to capture several of the viscoelastic properties, which were previously thought to be characteristic to biological protein macromolecules.Description
| openaire: EC/H2020/742829/EU//DRIVEN
Keywords
Other note
Citation
Martikainen, L, Bertula, K, Turunen, M & Ikkala, O 2020, ' Strain Stiffening and Negative Normal Force of Agarose Hydrogels ', Macromolecules, vol. 53, no. 22, pp. 9983-9992 . https://doi.org/10.1021/acs.macromol.0c00601
