Directly printing of upconversion fluorescence-responsive elastomers for self-healable optical application

Lanthanide ions (Ln(3+)) doped upconversion crystals (UCCs) have promising application in optical anti-counterfeiting device, biomedical sensors and volumetric displays. However, these designed optical devices cannot recover their functions after mechanical damage and scratches. Herein, the novel upconversion fluorescence-responsive disulfide crosslinked polyurethane (DSPU) self-healing elastomers were designed for the first time, including the impaction of red-green-blue UCCs into DSPU (DSPU-UCCs) films and screen-printed fluorescence patterns on DSPU films. The DSPU-UCCs films exhibit tunable red-green-blue upconversion emissions as well as favorable mechanical properties (1037% stretchability) and self-healing ability (97.8% efficiency). The further investigations of the surface scratches and rheology results show that the disulfide bonds offer more efficient metathesis efficiency at higher temperatures. Moreover, the fluorescence-responsive self-healing elastomers can be reprocessed and reshaped, thus showing outstanding recyclability and sustainability. Directly screen-printing method was employed to fabricate versatile fluorescence patterns on DSPU elastomers, which can replace the traditional methods of relying on high-cost molds or masks to fabricate patterns. Healing scratches electronic patterns and assembling a series of versatile fluorescence patterns suggest that the upconversion fluorescence-responsive DSPU elastomers are highly promising for implementation in practical applications.