Séminaire SIMM : Rint P. Sijbesma, Eindhoven University of Technology

Rint P. Sijbesma, Department of Chemical Engineering and Chemistry and Institute for Complex Molecular Systems, Eindhoven University of Technology, The
Netherlands

Strain stiffening in self-assembled biomimetic hydrogels

Soft tissues exploit the interplay between covalent and non-covalent interactions to balance dynamics and mechanical strength. More specifically, the cellular matrix is well-known to rely on self-assembly to effect motility but at the same time it can stiffen dramatically in response to strain, thereby protecting from catastrophic deformation.
The design of biomimetic strain-stiffening materials has great potential in tissue engineering or regenerative medicine due to the large scope of structural tuning of synthetic molecules as opposed to natural proteins. However, the development of synthetic strain stiffening materials has been limited to covalent polymers and therefore one of the most fundamental dynamic supramolecular aspects of nature’s hydrogels has been overlooked.
Here, we present hydrogels composed of self-assembling amphiphilic molecules that form long, semi-flexible fibers, whose morphology can be covalently fixated. Co-assembly with molecules having reactive groups allows for the controlled introduction of crosslinking points along the fiber contour which can be then reacted with a 5-arm cross-linker to obtain strain-stiffening gels mimicking the mechanics of filamentous protein networks.
In the lecture I will explore the effect of covalent fixation on the strain-stiffening properties, and I will show how the fibers can be cross-linked with a thermally responsive PNIPAM polymer to give networks that stiffen under strain as well as by heating.