Solvent-exchange triggered hydrogen bond activation strategy toward self-adaptive strong and tough organohydrogel artificial muscle

Abstract

Hydrogel actuators have aroused tremendous interests in various fields such as artificial muscles, biomedicine and wearable devices. However, hydrogel actuators face persistent challenges due to their intrinsic weak and hydrophilic networks, which result in brittle and weak mechanical properties after swelling. Here, we proposed a solvent-exchange hydrogen bond activation strategy to fabricate a highly strong and tough self-adaptive organohydrogel actuators (SOA). The glycerol releasing and water retention triggers abnormal swelling of SOA due to the cross-linking of tannic acid (TA) and polyvinyl alcohol (PVA) nanofibrillar network. After the hydrogen bond activation between PVA and TA, SOA shows a denser and porous nanofibrillar network with high tensile strength (5.4 ± 0.2 MPa), high fracture energy (134.9 ± 7.6 kJ/m2), and high toughness (18.5 ± 0.7 MJ/m3). Owing to its good processibility, an anisotropic multi-filament twisted fiber actuator that exhibits ultra-high modulus (83.5 ± 2.6 MPa) and humidity-sensitive actuation performance was developed. The proposed solvent-exchange strategy shows great potential for the rational design and fabrication of bionic strong and tough artificial muscles.