Light-Triggered Bending in Photochromic/Graphene Oxide Bilayers via Synergistic Photo-Thermal Actuation and Mechanical Amplification.

The design of soft actuators remotely controlled by optical triggering and propelling schemes requires materials that might combine ease of device fabrication and miniaturization with robust performance of moving parts and versatile and precise response to light stimuli. Here, light-triggered photochromic-doped poly(methyl methacrylate)/reduced graphene-oxide bilayers are proposed as effective actuation architectures, showing multi-photoaddressable bending and distinctive photothermal properties. By interlayer thermomechanical contrast and intrinsic mechanical amplification of photoinduced strain mismatch, these hybrid systems show good bending and load-lifting performance, broadband photothermal triggering, as well as faster thermal and actuation response compared to pristine photochromic films. Under UV illumination, measured displacements, exerted force, and response time reach values of about 200 μm, 2 mN, and the scale of few seconds, respectively. The photothermal conversion efficiency of the system is estimated to be at least 55%. Such properties make these architectures appealing as actuation elements for various device platforms, including segments of biomimetic components, and biomedical devices with precise structure-function design of the optical control.