Inorganic Hydrogels can be Flexible and Highly Extensible

Abstract

AbstractInorganic hydrogels have great potential in many applications as sustainable materials, but lack flexibility due to rigid network structures. Here, a novel strategy is proposed—an inorganic polymer hydrogel, prepared by crosslinking long‐chain polyphosphate (LPP) with M2+ ions (Ca2+, Mn2+, Mg2+, Ni2+), which effectively address the rigidity and fragility issues commonly associated with traditional inorganic gels. With the most stable hydration shell among those ions, Ni2+ tends to interact indirectly with LPP through hydrogen bonds rather than coordination bonds. The unique Ni2+‐phosphate interaction endows the Ni‐LPP hydrogels with ultrahigh elongation at break (≈15 000×). Further experiments reveal that the Ni2+‐phosphate motif can be applied to other hydrogels as an extension enhancement factor. The highly extensible, good conductive (1.06 ± 0.08 S m−1), self‐healing (within 30 s and without stimulation), arbitrarily shapeable, and nonflammable Ni‐LPP inorganic hydrogel indicates a bright future in flexible electronics, environmental remediation, and beyond.