Fluorescein-Functionalized Conjugated Polydiacetylenes with Excellent Reversible Thermochromic Properties under Thermal and 980 nm Near-Infrared Light Stimuli

The design of stimulus-responsive materials with a reversible colorimetric ability is of great value in the applications of sensors, anticounterfeiting, displays, and photodetection. In this article, the chromatic behavior of fluorescein-substituted polydiacetylene (FPDA) was researched in aqueous and solid films. The strong hydrogen bonding and aromatic interactions of the headgroup in FPDA led to an intriguing reversible thermochromism with a green-to-red color transition from 30 to 100 °C in solution and a blue-to-red color transition from 30 to 150 °C in the solid film. The relationships between colorimetric response values and the temperatures indicated the quantitative analysis of the temperature of PDA in both solution and solid films. Furthermore, FPDA displays a reversible color transition from blue to red in response to 980 nm near-infrared light with a higher power light density. Our work may pave the way for broadening the potential applications of PDA-based materials in the field of sensors, display materials, photodetectors, and anticounterfeiting barcode systems.