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

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. Vinyl-functionalized molybdenum disulfide (v-MoS2) nanosheets serve as an organic-inorganic hybridized crosslinker for the polymerization of acrylamide, designing a network with the noncovalent adsorption and covalent bonding interactions simultaneously. The network can not only effectively transfer load but also dissipate energy, leading to high performance for the hydrogels. These properties are highly advantageous for the practical applications of the hydrogels as robust and smart bionic robots. [Display omitted] •v-MoS2 nanosheets are exfoliated and functionalized with the aid of PEI-AGE.•v-MoS2 nanosheets serve as a chemical and physical cross-linker to prepare hydrogels.•Such designing principles enable effective load transfer and energy dissipation.•Hydrogels manifest robust, ultrastretchable, notch-insensitive and anti-fatigue.•Hydrogels can be used as robust biomimetic fish and butterfly.