Photoinduced deformation of amorphous polyimide enabled by an improved azobenzene isomerization efficiency

Abstract

Photodeformable azobenzene-containing polyimides (azo-PIs) have attracted attention due to their photo-response, good mechanical properties, and thermal stability. The deformation principle of azo-PIs mainly depends on the accumulation of conformational changes in one direction by polarized-light irradiation or pre-stretching. Herein, we synthesize a new deformable azo-PI and put forward a different strategy to achieve photodeformation by improving the azobenzene isomerization efficiency, which is attributed to the incorporation of azobenzene into the side chains of the polyimide (s-azo-PI). The s-azo-PI film exhibits reversible bending behaviour under alternate ultraviolet and visible light irradiation without using polarized light or pre-stretching. By means of this photodeformable behaviour, origami- or kirigami-inspired deformable 3D-structure objects, such as a cubic box and roller, are easily manufactured without any prior treatment, showing the potential to broaden the application of azopolymers in smart 3D actuators.