New H-Shaped Conjugated Reactive Liquid Crystals with Exceptionally Low Birefringence for Advanced Polymer Optics

Abstract

The growing demand for advanced optical materials in augmented reality (AR), virtual reality (VR), and imaging technologies requires new strategies to overcome the limitations of conventional high-birefringence systems. Herein, the design, synthesis, and characterization of a novel series of conjugated H-shaped liquid crystal (LC) molecules is reported with exceptionally low birefringence. These materials combine LC behavior with reactive end groups, enabling their integration into highly transparent, well-aligned polymer films. The unique molecular architecture balances the extraordinary and ordinary refractive indices, minimizing anisotropy without compromising optical quality. Their incorporation into cholesteric liquid crystal (CLC) systems resulted in narrow reflection bandwidths of 37 nm on average across the visible spectrum, maintaining high transparency and preventing phase separation. The projection of sharp images and videos is successfully achieved on a transparent CLC coating that selectively reflects red, green, and blue wavelengths. These results demonstrate the significant potential of H-shaped conjugated mesogens for the next generation of optical and photonic devices requiring precise birefringence control and optical clarity.