A bidirectionally reversible light-responsive actuator based on shape memory polyurethane bilayer

In this work, a simple method is proposed for the preparation of bidirectionally reversible light-responsive shape memory polyurethane (SMPU) bilayer. This SMPU bilayer consists of a 4,4-azodibenzoic acid (Azoa) containing SMPU (SMPU-Azoa) layer and a carbon black (CB) containing SMPU (SMPU-CB) layer. A reversible deformation is realized when the two sides are exposed to ultraviolet (UV) and infrared (IR) lights, respectively. The working mechanism is the trans?cis isomerization of SMPU-Azoa layer and the photo-thermal effect of SMPU-CB layer. The effect of the filler content and the thickness ratio of bilayer is systematically studied. The reversible bending angle of the SMPU bilayer can exceed 30? in 16 s for one cycle when the Azoa and CB contents are 5 wt% and 0.5 wt%, respectively, and the thickness ratio of SMPU-Azoa layer to SMPU-CB layer is 1/1.3. Furthermore, a microrobot based on such LSMP bilayer is demonstrated.

Automated summary

A bidirectionally reversible light-responsive shape memory polyurethane (SMPU) bilayer was proposed, consisting of SMPU-Azoa and SMPU-CB layers, which can realize reversible deformation under ultraviolet and infrared lights. The filler content and thickness ratio of the bilayer were found to significantly affect the reversible bending angle of the SMPU bilayer, with a maximum angle exceeding 30° when Azoa and CB contents are 5wt% and 0.5wt%, respectively.