Visualization of photocuring and 4D printing with real-time phosphorescence

Facile and real-time visualization monitoring of photocuring process is a challenge. Base on the fact that pure organic room-temperature phosphorescence (RTP) is quite sensitive and easy to be regulated via internal rigidity changes of the surrounding environments of phosphore dyes, competitive organic candidates with advantageous RTP are brought into the fields of photocuring and 4D printing materials. Herein, we have put forward a strategy to introduce phosphors into photocuring materials because of the rigidity-increasing liquid-to-solid transformation. Based on this, the obtained luminescent curing films achieve RTP emission with full-color display of blue, green, and orange. Visible real-time monitoring can be realized by observations of phosphorescent changes, thus allowing the recording of curing speed, internal environment, and conversion during the curing process. Moreover, these curing materials successfully complete 4D printing and shape-memory process, demonstrating continuous dynamic deformation in fabricated 2D materials (the fabricated flower-pattern film) and 3D materials (the spaceman and pandas) with vivid RTP emission. Especially, the further regulations of the real-time phosphorescence can realize significant visualization in these 4D printing materials. We believe this discovery with the replacement of phosphors opens a door to further extension in the field of curing materials and more sophisticated morphing in 4D printing.