An interface engineering-driven performance enhanced PVA@PPy-LCEs photothermal actuator

Photothermal liquid crystal elastomers (LCEs)-based soft actuators have been received widely attention for their precise and untethered controlling behaviors. However, it remains a vital issue that needs to be overcome, that is, for the mismatch of mechanical moduli, the interface instability is prone to occur between inorganic photothermal additives and LCEs matrix, resulting in poor mechanical strength and actuation performance. Hence, in this study, a photothermal soft actuator was prepared via integrating a Polyvinyl alcohol (PVA)-coated photothermal Polypyrrole (PVA@PPy) additive and a LCEs substrate. Here, the introduction of PVA coating can create a strong and efficient hydrogen-bond interaction between the additive and the substrate, which will construct the uniform photothermal and mechanical reinforcement network, achieving the optimal mechanical performance of 47.1 MPa and actuation capacity of maximum strain of 46.5% and speed of 4.15 s^-1 when the content of PVA@ PPy is 2.0 wt%. In addition, the influence of the size effect and the chemical interaction was also clearly clarified, showing that the order parameter decreases by 39% as the intermolecular distance of the liquid crystals increases by 0.12 Å during actuation. Furthermore, this soft actuator can realize four kinds of controlled motions just by adjusting the size and position of the IR light shone, achieving the largest out-of-plane and in-plane lateral bending angles of about 105^o and 60^o, respectively. Based on this, a soft robot was designed to finish the continuous behaviors, and this actuator was dexterously employed to imitate the locomotion behaviors of human muscle and phototaxis plants/animals, which is also benefitted from its excellent photothermal deformation effect, underscoring its considerable promise in the realm of adaptive bionic systems.