A New Kind of Nonconventional Luminogens Based on Aliphatic Polyhydroxyurethane and its Potential Application in Ink-Free Anticounterfeiting Printing.

Organic luminogens have extensive applications due to their unique photophysical properties. In recent years, non-conjugated organic luminogens, in contrast to traditional conjugated luminogens, have gained much attention due to their facile preparation, environment-friendliness and biocompatibility. In this study, a new kind of nonconventional luminogens based on dynamic covalent cross-linked polyhydroxyurethane is reported for the first time. The new luminogens not only exhibit intrinsic strong fluorescent emissions at solid states, but also possess high mechanical properties along with good shape memory and self-healing properties. Especially, the new luminogens are synthesized from aliphatic polyfunctional cyclic carbonate and amines via a much more straightforward way, avoiding the use of toxic isocyanates. Investigations indicated that the intrinsic luminescence of the resultant luminogens was induced by the crosslinking of polymer chains and can be well tuned by controlling the degree of crosslinking. By taking advantage of the unique characteristics of the resultant polymer luminogens, we further develop a facile method, named "light-mediated ink-free screen printing", for anticounterfeiting paper fabrication. Different from traditional ink-based printing technology, the new method used UV-light instead of expensive security ink to encode anticounterfeiting information on natural cellulose paper. The anticounterfeiting information is stable under various wet conditions, showing promising applications in the fast-growing counterfeiting of pharmaceuticals, packaging and food industry.