Thermal responsive smart lanthanide luminescent hydrogel actuator

Among stimuli-responsive soft materials, thermal responsive hydrogels are the most attractive one because temperature is the most easily regulated external stimuli. We here report a thermal responsive bilayer smart luminescent hydrogel actuator with tough mechanical strength and thermal reversible deformation behavior. The bilayer hydrogel is composed of Poly(N-isopropylacrylamide)-Laponite-Tb complex (PNIPAM-Lap-Tb.L3) layer and Poly(N,N-dimethylacrylamide)-Laponite-Eu complex (PDMA-Lap-Eu.L3) layer. Upon alternative heat -ing and cooling, the PNIPAM-Lap-Tb.L3 layer undergoes reversible shrink and expansion, while the PDMA-Lap-Eu.L3 layer is not affected, leading to asymmetric deformation behavior. The luminescent intensity of the bilayer hydrogel was enhanced by heating, and the maximum bending angle was 371 degrees in 15 min. By processing the bilayer hydrogel into complex 2D and 3D structure, we further demonstrate their great potential as smart soft actuators.