Liquid Crystal Networks on Thermoplastics: Reprogrammable Photo-Responsive Actuators.

Arbitrary shape (re)programming is appealing for fabricating untethered shape-morphing photo-actuators with intricate configurations and features. We present re-programmable light-responsive thermoplastic actuators with arbitrary initial shapes through spray-coating of polyethylene terephthalate (PET) with an azobenzene-doped light-responsive liquid crystal network (LCN). The initial geometry of the actuator is controlled by thermally shaping and fixing the thermoplastic PET, allowing arbitrary shapes, including origami-like folds and left- and right-handed helicity within a single sample. The thermally fixed geometries can be reversibly actuated through light exposure, with fast, reversible area-specific actuation such as winding, unwinding and unfolding. By shape re-programming, the same sample can be re-designed and light-actuated again. The strategy presented here demonstrates easy fabrication of mechanically robust, recyclable, photo-responsive actuators with highly tuneable geometries and actuation modes.