Synthesis and characterization of chiral fluorescent liquid crystal polymers containing naphthalimide and coumarin units

In this paper, a naphthalimide‑based fluorescent liquid crystal monomer containing coumarin groups and a series of fluorescent cholesteric liquid crystal polymers were synthesised. The compounds and polymers were characterised using conventional methods. The results indicated all polymers possessed dual optical properties of fluorescence and selective reflection. The 5% thermal weight loss temperature of the polymer is greater than 300°C, indicating good thermal stability. The fluorescence decreases during the heating process and re-enhances during the cooling process. The polymers emitted different intensity fluorescence under UV light as the content of fluorescent monomers varies. The fluorescence intensity has a certain relationship with temperature and aggregation-caused quenching effect only occurs when the content of fluorescent monomer in the polymer exceeds 20% (i.e., at25% in FCP7). Synthesised polymers have potential application prospects in anti-counterfeiting, microelectronics, optical devices and other fields.