Design, synthesis, and characterization of bent-core mesogen-jacketed liquid crystalline polymers

Abstract

We report the design, synthesis, and characterization of a series of mesogen-jacketed liquid crystalline polymers with bent-core liquid crystals (BCLCs). For the first time, BCLC mesogens were directly side-attached to the polymer backbone and bent-core mesogen-jacketed liquid crystalline polymers (BMJLCPs) were achieved. Both three-ring and five-ring mesogens were employed. The n-alkoxy substituent lengths for the three-ring and five-ring BMJLCPs were controlled as n = 1-5 and n = 6-16, respectively. Various characterization techniques such as differential scanning calorimetry, wide-angle X-ray diffraction, and polarized light microscopy were used to study their mesomorphic phase behavior. The monomers of five-ring BMJLCPs with relatively long tails showed mesophase behavior. Columnar liquid crystalline phase was observed in both three-ring and five-ring BMJLCPs. Columnar rectangular (Φ R) phase was observed in the three-ring system. In the five-ring BMJLCPs, relatively short-tail homologues possess Φ R phase, while columnar hexagonal phase was observed in the long-tail samples. The differences in the phase structures were attributed to the "softness" of the macromolecular BMJLCP column surface. © 2006 American Chemical Society.