π-Extended Viologen-Based Lyotropic Chromonic Liquid Crystal Reactive Mesogen: Uniaxial Orientation and Photopolymerization for Transmittance and Color Controllable Electrochromic Smart Glass.

Pham, Huan Huu; Rim, Minwoo; Wi, Youngjae; Hyeong, Jaeseok; Koo, Jahyeon; Lee, Kyung Min; Godman, Nicholas P; McConney, Michael E et al. · Adv Mater · 2025

basic_science · Level V

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Abstract

To advance the development of an electrochromic (EC) smart glass, a π-extended viologen-based lyotropic chromonic liquid crystal (πV-LCLC) reactive mesogen (RM) is newly designed and successfully synthesized in this study. By extending the π-conjugation length of viologen, the πV-LCLC RM forms a stable LCLC phase at room temperature and retains its chemical integrity during the EC reactions, exhibiting reversible transitions across three redox states: dication (D), cation-radical (C), and neutral (N). A uniaxially oriented nanostructure is constructed on the macroscopic scale through shear-coating and molecular self-assembly. Subsequent photopolymerization of the uniaxially oriented πV-LCLC film significantly enhances its mechanical and chemical stability while enabling polarization-dependent transmittance and distinct color transitions. This newly developed πV-LCLC RM facilitates the fabrication of energy-efficient EC optical devices with tunable transmittance and multicolor modulation, and it is operable at a low voltage of 2.5 V.