Laser-Writing Multicolor Fluorescent Polyurethane for Facile Display and Potential Application in Luminescent Labeling

Fabrication of dual-color fluorescent patterning with multiple sophisticated properties through a facile strategy is a great challenge, although it is highly desirable for the rapid development of modern society. Herein, we explore a novel strategy to realize dual-color fluorescent patterning by utilizing laser writing to generate local photoheat for rearrangement of electron groups containing n and π electrons to adjust electron delocalization. A polyurethane containing T-shaped quadruple hydrogen bonding moieties (IU-PU_X) is designed to provide a rigid and strong H-bonding donor–acceptor structure. It is found that the fluorescence of the materials undergoes a transition from blue to cyan, green, and yellow successively upon heating due to the formation of electron delocalization domains of varying sizes through the rearrangement of hierarchical hydrogen bonds. The patterning process is efficient and cost-effective. The pattern has high resolution and can be erased on demand. In addition, the IU-PU_X exhibits good self-healing and excellent adhesion properties due to the presence of a large amount of hydrogen bonds. The IU-PU_X film with laser written patterns can be used as labels that could be easily adhered to various object surfaces and can be easily peeled off at high temperatures when needed, avoiding heavy consumption of single-use or transient labels. This study provides a facile and high-efficiency method to fabricate dual-color label materials with multiple properties.