The Biomimetic Smart Material Group at QIBEBT (Chaoxu LI) found that ultrasonically exfoliated WS2 strongly bound in thin layers to alginate. The nanofilm exhibited excellent mechanical properties with a high tensile strength and toughness superior to natural bio-composites such as nacre, bone and dentin. It can be self-heated up to 300 oC within several seconds under low-dose radiation due to its high photo-thermal ability of WS2 nanosheets. The water-absorption and cation-binding capacities of sodium alginate endow the composite film with smart actuating applications in the forms of photo-driven motor, walking robot and gripper, etc. For example, a soft gripper was created with four stripes of actuating film as cantilevers. The grasping/releasing motion was driven by switching light radiation on and off. The responsiveness was swift (e.g., 12 s to grasp and 10 s to release), being comparable with or even superior to other reported smart grippers. Due to the super mechanical properties, the gripper could grab a steel ball with the weight 500 times heavier than the gripper itself.
CAS news release, January 12, 2017