Reversible Emission Color, Brightness, and Shape Changes of AIEgen-containing Bulk Polymers

Bulk polymers generally exhibit faster response, higher shape-deformation speed, and stronger mechanical properties than the hydrogels. However, it still remains a formidable challenge to enable bulk polymers to exhibit reversible changes in shape and fluorescence simultaneously. Herein, for the first time, the temperature-responsive reversible changes in fluorescence color, brightness, and shape of semi-crystalline poly( ε -caprolactone) (PCL) network doped with a D-A based aggregation-induced emission luminogen (AIEgen) is realized. The fabricated flower-like and dragonfly-shaped actuators show reversible blooming-closing and wing fanning behaviors, respectively, as well as reversible fluorescence-changing effects. Notably, the response and shape-deformation speed as well as mechanical properties of the system is much better than the reported hydrogels. Moreover, a smart switch is developed to demonstrate the potential applications. The stick fabricated by the sample can lift and release an object 1000 times larger than its weight, serving as a color-changing artificial muscle. This material design strategy may shine light on the design and preparation of other reversible shape-deformation polymers in combination with stimuli-responsive luminescence-changing AIEgens, such as mechanochromic, thermochromic, and photochromic luminogens.