Mechanically robust smart hydrogels enabled by an organic-inorganic hybridized crosslinker

Abstract The emerging soft electronics and robots are eagerly seeking for soft materials possessing not only comprehensive mechanical properties but also smart stimuli-responsive property, whose fabrication however remains a great challenge. Herein, we develop a series of high-performance smart hydrogels crosslinked and reinforced by an organic-inorganic hybridized crosslinker composed of multi-functional polymer adsorbed molybdenum disulfide (v-MoS2). The multi-functional polymer is synthesized by grafting polyethyleneimine with multiple vinyl groups. Such molecular design enables it to serve as a surfactant to assist the exfoliation and stabilization of v-MoS2 nanosheets through hydrophobic and electrostatic interactions, thereby forming the hybridized crosslinker to crosslink polyacrylamide (PAM) hydrogels through both chemical bonds and physical interactions. The crosslinking points can effectively transfer load between the molecular chains and v-MoS2, and moreover dissipate energy through hydrophobic and electrostatic interactions. Therefore, the hydrogels not only are mechanically robust with tensile strain up to 3500% and strength up to 645 kPa, but also show outstanding notch-insensitivity and anti-fatigue property. Combining with the photothermal effect of MoS2, robust biomimetic fish and butterfly with dual photoresponsivity and thermosensitivity are designed, which can well mimic the self-defense process of marine and terrestrial organisms under external stimulations.