3D-Printable Room Temperature Phosphorescence Polymer Materials with On-Demand Modulation for Modulus Visualization and Anticounterfeiting Applications.

Conventional room temperature phosphorescence (RTP) polymer materials lack a dynamic structural change mechanism for on-demand phosphorescence emission, limiting their application in specific scenarios, such as smart devices. However, the development of RTP polymer materials with an on-demand emission capability is highly attractive yet rather challenging. Herein, we report a novel RTP polymer material that doped purely organic chromophores into a polymer network with numerous free hydroxyl side chains. This unique polymer material can be 3D printed with RTP activated through thermal-triggered nonequilibrium transesterification, where on-demand phosphorescence emission is achieved because of the increased cross-linking degrees such that the thermal motion of chromophores is effectively restricted. As a result, ultralong RTP emission is successfully observed due to enhanced stiffness in the polymer network. Importantly, the modulus changes of the polymer during nonequilibrium transesterification are intuitively visualized based on the intensity of phosphorescence emission. Through liquid crystal display (LCD) 3D printing, complex shaped and multimaterial structured objects are demonstrated, targeting the information encryption of printed objects and on-demand regional emission of multicolored phosphorescence. This study would provide an avenue to control RTP with on-demand emission and contributes to the field of anticounterfeiting and detection applications for intelligent RTP materials.