Helical columnar phase of mesogen-jacketed liquid crystal polymers for efficient circularly polarized luminescence

Abstract

Chiral luminescent liquid crystals show unique application values in the preparation of circularly polarized luminescent (CPL) materials with a large luminescence dissymmetry factor (g_lum) and have received widespread attention in recent years. The luminescent mesogen-jacketed liquid crystal polymers (MJLCPs) show good thermal stability, stable phase structure, and excellent luminescent performance. However, how to design and synthesize MJLCPs with CPL-active is still a challenge. In this article, we developed a copolymerization strategy for preparing MJLCPs with CPL-active. Monomer MJ0CN12C with AIEE characteristics and monomer MJ0Chol bearing chiral cholesterol chromophore were polymerized to synthesize the mesogen-jacketed liquid crystal homopolymers PMJ0CN12C, PMJ0Chol, and mesogen-jacketed liquid crystal copolymers abbreviated as CN(x)-Chol(y). PMJ0CN12C, PMJ0Chol and CN(x)-Chol(y) show a stable phase structure. When heated to 300 °C, their liquid crystal phase structure still exists stably. All the copolymers CN(x)-Chol(y) show AIEE and CPL characteristics while homopolymers PMJ0CN12C and PMJ0Chol show no CPL signal. Meanwhile, as the content of chiral cholesterol component increases, the g_lum values of CN(x)-Chol(y) initially increase and then decrease. For CN(0.6)-Chol(0.4), the g_lum value can achieve 0.081, showing excellent CPL emission.