Janus Oligomers Demonstrating Full-Spectrum Visible Light Reflection and Tunable Photoluminescence towards Dual-Mode Dynamic Anti-Counterfeiting

Stimulus-responsive multimodal optical materials demonstrating tunable optical behaviors possess significant application in optoelectronic materials and devices. Introducing fluorescent elements into liquid crystal structures is a common strategy. The design of hybrid optical structure at molecular level is seldom reported. Herein, novel Janus oligomers (JOs) combining the chiral nematic liquid crystalline (CNLC) units and the photoluminescent (PL) units on organosilicon oligomers by molecular grafting are proposed. The as-prepared JOs display brilliant visible light reflection originating from the chiral arrangement of the CNLC segments. The discrete pyrene chromogenic segments in the CNLC matrix enable the quantum yield and PL lifetime of JOs to be up to 38.58% and 68.45 ns. Furthermore, the JOs present dual-mode thermochromic performances, the blue-shift reflection across the full-spectrum visible light region, and the highly sensitive PL evolution. The JOs can be manufactured into dynamic anti-counterfeiting patterns with fast and reversible response by screen printing. The Janus optical structure enabled by chemically coupling different optical elements at the molecular level provides a templated strategy to create the next generation of intelligent hybrid optical materials.