Connecting the Stimuli-Responsive Rheology of Biopolymer Hydrogels to Underlying Hydrogen-Bonding Interactions

Connecting the Stimuli-Responsive Rheology of Biopolymer Hydrogels to Underlying Hydrogen-Bonding Interactions

Giubertoni, Giulia (AMOLF)
Burla, Federica (AMOLF)
Bakker, Huib J. (AMOLF)
Koenderink, G.H. (TU Delft BN/Gijsje Koenderink Lab; Kavli institute of nanoscience Delft; AMOLF)

2020

Many biopolymer hydrogels are environmentally responsive because they are held together by physical associations that depend on pH and temperature. Here, we investigate how the pH and temperature responses of the rheology of hyaluronan hydrogels are connected to the underlying molecular interactions. Hyaluronan is an essential structural biopolymer in the human body with many applications in biomedicine. Using two-dimensional infrared spectroscopy, we show that hyaluronan chains become connected by hydrogen bonds when the pH is changed from 7.0 to 2.5 and that the bond density at pH 2.5 is independent of temperature. Temperature-dependent rheology measurements show that because of this hydrogen bonding the stress relaxation at pH 2.5 is strongly slowed down in comparison to pH 7.0, consistent with the sticky reptation model of associative polymers. From the flow activation energy, we conclude that each polymer is cross-linked by multiple (5-15) hydrogen bonds to others, causing slow macroscopic stress relaxation, despite the short time scale of breaking and reformation of each individual hydrogen bond. Our findings can aid the design of stimuli-responsive hydrogels with tailored viscoelastic properties for biomedical applications.

http://resolver.tudelft.nl/uuid:12ff7d97-7e79-4816-9d21-24cb24648a28

https://doi.org/10.1021/acs.macromol.0c01742

0024-9297

Macromolecules, 53 (23), 10503-10513

Institutional Repository

journal article

© 2020 Giulia Giubertoni, Federica Burla, Huib J. Bakker, G.H. Koenderink