title: Ultra-responsive soft matter from strain-stiffening hydrogels.
abstract: The stiffness of hydrogels is crucial for their application. Nature's hydrogels become stiffer as they are strained. This stiffness is not constant but increases when the gel is strained. This stiffening is used, for instance, by cells that actively strain their environment to modulate their function. When optimized, such strain-stiffening materials become extremely sensitive and very responsive to stress. Strain stiffening, however, is unexplored in synthetic gels since the structural design parameters are unknown. Here we uncover how readily tuneable parameters such as concentration, temperature and polymer length impact the stiffening behaviour. Our work also reveals the marginal point, a well-described but never observed, critical point in the gelation process. Around this point, we observe a transition from a low-viscous liquid to an elastic gel upon applying minute stresses. Our experimental work in combination with network theory yields universal design principles for future strain-stiffening materials.
authors.affiliation: Department of Molecular Materials, Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 Nijmegen, The Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: Jaspers
authors.affiliation: Department of Physics and Astronomy VU University, De Boelelaan, 1081 Amsterdam, The Netherlands.
authors.forename: Matthew
authors.initials: M
authors.lastname: Dennison
authors.affiliation: Department of Molecular Materials, Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 Nijmegen, The Netherlands.
authors.forename: Mathijs F J
authors.initials: MF
authors.lastname: Mabesoone
authors.affiliation: Department of Physics and Astronomy VU University, De Boelelaan, 1081 Amsterdam, The Netherlands.
authors.forename: Frederick C
authors.initials: FC
authors.lastname: MacKintosh
authors.affiliation: Department of Molecular Materials, Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 Nijmegen, The Netherlands.
authors.forename: Alan E
authors.initials: AE
authors.lastname: Rowan
authors.affiliation: Department of Molecular Materials, Radboud University Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 Nijmegen, The Netherlands.
authors.forename: Paul H J
authors.initials: PH
authors.lastname: Kouwer