Zwitterionic ionogels with water-mediated stiffness transition for shape memory and moisture electric generation

Moisture-sensitive gels with recyclable and switchable mechanics hold great promise for electronic generation. However, the volume, mechanical, electrical stability of gels during repeated hydration-dehydration remain a big challenge. In this study, we have developed a high-strength ionogel by incorporating a polyacrylic acid (PAA) network with multiple hydrogen bonds into the polyzwitterion-ionic liquid (PVBIPS-VEIMBF4) network. The resulting ionogel exhibits an exceptional breaking strength of 67 MPa and significant water-induced softening (2600-fold modulus decrease) with the elongation of approximately 708%. Moreover, it remains stable over 7 rehydration processes without volume deformation, simultaneously exhibits excellent water/heat induced shape memory behavior. Additionally, due to the protonation ability of polyelectrolytes and the exceptional hydration ability of zwitterions, a single gel-based MEG can consistently produce a high voltage of 1.17 V at 85% outdoor humidity. With diverse applications in different states, this excellent ionogel demonstrates enormous potential for sustainable development of green materials.