A four-blade light-driven plastic mill based on hydrazone liquid-crystal networks

Abstract The first light-driven plastic mill is developed, which converts the incoming light directly into a continuous rotation. This device is composed of four blades made of hydrazone-based liquid crystal polymer films able to bend under focused light irradiation and to create a force causing the rotation of the mill. The mechanism of motion originates from the fast photo-thermal isomerization around the C N bond of hydrazones. We show that by accelerating the rate of the thermal Z to E back-isomerization of hydrazones, macroscopic deformation with fast strain rate can be obtained. The rapid motion of the film is the key factor in obtaining the continuous rotatory motion of the mill. These results broaden the range of molecular switches available for macroscopic motion of light-driven organic devices and offer new insights for single-step energy conversion in soft robotics and automated systems.