Engineering the chemical structure of H-shaped reactive molecules for negative dispersion of retardation

Five kinds of H-shaped reactive monomers with different central core groups were newly designed and synthesized for obtaining a negative dispersion of retardation. The H-shaped molecules were mixed with cylindrical reactive mesogen molecules and the mixtures with the H-shaped molecules wherein a benzene or a naphthalene ring is in the core presented a wide liquid crystalline phase and a uniform orientation. The retarder film made by UV-polymerization of the mixtures showed a positive or a negative dispersion of retardation depending on the chemical structure of the H-shaped molecules. To understand the different dispersion properties, the molecular orientation of the H-shaped molecules was investigated by measuring the UV-vis absorption anisotropy and out-of-plane retardation of the samples. The retarder sample showed a negative dispersion of retardation when the imine groups of the H-shaped molecules were aligned orthogonal to the slow axis of the sample.

Automated summary

This study designed and synthesized five different H-shaped reactive monomers with various central core groups to achieve a negative dispersion of retardation. Mixing the H-shaped molecules with cylindrical reactive mesogen molecules resulted in a wide liquid crystalline phase and a uniform orientation when a benzene or a naphthalene ring was present in the core. Polymerizing the mixtures using UV light produced retarder films with either positive or negative dispersion of retardation depending on the chemical structure of the H-shaped molecules. The molecular orientation of the H-shaped molecules was investigated using UV-vis absorption anisotropy and out-of-plane retardation measurements, revealing that the retarder sample exhibited negative dispersion when the imine groups of the H-shaped molecules were aligned orthogonal to the slow axis of the sample.