Thiourea-Based Soft Actuators from Photo-triggered Fluoride Generation and Amplification

The development of soft actuators is an important research area due to their wide application range, specifically for biomimetic soft robotics. Photo-responsive or -triggered actuators have also gained much attention, mainly because they allow for remote triggering with spatial and temporal control. In this study, we prepare bilayer actuators composed of thiourea (TU) networks integrated with fluoride-generating and fluoride-amplifying molecules. These molecules demonstrate fluoride generation and amplification inside the TU actuators by UV irradiation. The photo-triggered TU actuators produce relatively large deformations due to the volume contraction of the TU films with binding of photo-generated and amplified fluoride. The bound fluoride can be removed by a protonation process using a protic solvent that allows the photo-active TU actuators to be recycled. Such photo-triggered TU actuators are potentially useful for micromechanical systems, such as robotic arms, oscillators, and transmission devices.