Low-molecular-weight gelators (LMWGs)-based supramolecular hydrogels, self-assembled by small molecules via noncovalent interactions, have been recently attracted great attentions due to their unique structure-property relationship and potential applications spanning from functional materials to biomedical devices. Unfortunately, many LMWGs-based supramolecular hydrogels are mechanical weak and can not even be handled by conventional tensile and tearing tests. Here, we propose several design principles to fabricate new LMWG-based hydrogels with a true double-network structure (G4.K+/PDMAAm DN gels), consisting of the supramolecular self-assembly of guanosine, B(OH)3 and KOH as the first, physical G4.K+ network and the covalently cross-linked poly(N, N’-dimethyacrylamide) (PDMAAm) as the second, chemical network. Different from those LMWGs-based supramolecular hydrogels, G4.K+/PDMAAm DN gels exhibit high tensile properties (elastic modulus=0.307 MPa, tensile stress=0.273 MPa, tensile strain=17.62 mm/mm, and work of extension=3.23 MJ/m3) and high toughness (tearing energies=1640 J/m2). Meanwhile, the dynamic, noncovalent bonds in the G4.K+ network can reorganize and reform after being broken, resulting in rapid self-recovery property and excellent fatigue resistance. The stiffness/toughness of G4.K+/PDMAAm DN gels can be recovered by 65%/58% with 1 min resting at room temperature, and the recovery rates are further improved with the increase of temperatures and resting times. Interestingly, G4.K+/PDMAAm DN gels also exhibit UV-triggered luminescence due to the unique G4-quartets structure in G4.K+ supramolecular first network. A new toughening mechanism is proposed to interpret the high strength and toughness of G4.K+/PDMAAm DN gels. We believe that our design principles, along with new G4.K+/PDMAAm DN gel system, will provide a new viewpoint for realizing the tough and strong LMWGs-based gels.

文章链接https://pubs.acs.org/doi/10.1021/acs.chemmater.8b00063