Regulating Mechanical Properties of Polymer-Supramolecular Double-Network Hydrogel by Supramolecular Self-assembling Structures

Main observation and conclusion Polymer-supramolecular double-network hydrogels (PS-DN hydrogels) often show much improved recovery rates than conventional double-network hydrogels because of the fast self-assembling properties, making them attractive candidates for tissue engineering and flexible electronics. However, as the supramolecular network is dynamic and susceptible to break under low strains, the overall mechanical properties of PS-DN hydrogels are still limited. Here, we report the mechanical properties for PS-DN hydrogels can be significantly improved by tuning the supramolecular network structures. A single amino acid change of the self-assembling peptide can tune the assembled structures from nanofiber to nanoribbon. Such a microscopic structural change can greatly increase the Young's modulus (107.4 kPa), fracture stress (0.48 MPa), and toughness (0.38 MJ center dot m(-3)) of the PS-DN hydrogels. Moreover, the structural change also leads to slightly faster recovery rates (< 1 s). We propose that such dramatically different mechanical properties can be understood by the impact of individual peptide rupture events on the overall network connectivity in the two scenarios. Our study may provide new inspirations for combining high mechanical strength and fast recovery in double network hydrogels by tuning the supramolecular network structures.