Abstract
The engineering applications of hydrogels are generally limited by the common problem of their softness and brittlness. In this study, a composite double network ionic hydrogel (CDN-gel) was obtained by the facile visible light triggered polymerization of acrylic acid (AA), polyvinyl alcohol (PVA), and hydrolyzed triethoxyvinylsilane (TEVS) and subsequent salt impregnation. The resulting CDN-gels exhibited high toughness, recovery ability, and notch-insensitivity. The tensile strength, fracture elongation, Young's modulus, and toughness of the CDN-gels reached up to ~21 MPa, ~700%, ~3.5 MPa, and ~48 M/m(3), respectively. The residual strain at a strain of 200% was only ~25% after stretch-release of 1000 cycles. These properties will enable greater application of these hydrogel materials, especially for the fatigue resistance of tough hydrogels, as well as broaden their applications in damping.