Collaborative "Dual-Step" Stimuli-Responsive Polymer Dye and Its Applications in Information Encryption

Information encryption is essential for information security.However,constructing a collaborative multiple-information encryption systemwith elaborate design and intuitionistic displays is challenging.In recent years, owing to their wide applications in sensing, intelligentswitch, and information encryption, stimuli-responsive fluorescentmaterials have attracted the attention of scientists. Inspired bythe multi-component collaborative step-by-step strategy from biology,we designed and synthesized a collaborative "dual-step"stimuli-responsive fluorescent copolymer poly(NIPAm-co-1-vinylimidazole-co-Rh-2) (PNVRh-2) with high colorcontrast and good reversibility (>10 cycles) after treatment bymultiplestimuli. Using this strategy, we introduced rhodamine units with anacid-induced ring-opening effect and an electron-rich imidazole sidechain into poly(N-isopropylacrylamide) (PNIPAm).By combining these components, the conventional one-step acid-inducedluminescence process was transformed into a dual-step luminescenceprocess triggered by acid and heat. The fluorescence rate and intensityof PNVRh-2 could be manipulated by adjusting the pH and temperature.Contactless thermoprinting and erasable imaging were achieved. Furthermore,the great potential of PNVRh-2 in programmatic temperature-controlledinformation display and information encryption was illustrated, whichoffers a perspective for designing and optimizing high-performanceinformation encryption materials.