Stimuli-responsive hydrogels are flourishing; however, a multiresponsive luminescent hydrogel actuator in which the stimuli do not interfere with each other is still difficult to produce. Here, a smart luminescent bilayer hydrogel actuator with shape memory and reversible luminescence switch behaviors under the co-stimulation of pH and heating is reported. Under alkaline condition, chitosan-containing layer generates physical microcrystals to fix the temporary shape of the actuator while lanthanide emits bright luminescence. Upon acid treatment, the actuator recovers to its original shape and the luminescence is quenched since the "antenna effect" between organic ligand and lanthanide ions is disrupted. It is to be noticed that this multiresponsive cycle can be repeated several times without interfering each other. This work is expected to have potential application prospects in the fields of biomimetic soft robots, sensors, and camouflage.
Keywords: hydrogel actuator; lanthanide; luminescence switch; luminescent soft material; multistimuli-responsive.