2025/10/06 by Maksym, Andriy Z., Andrushchak, Anatoliy, Shchur, Yaroslav +6
#Natural Sciences and Mathematics::530: Physics::530.4: States of Matter #Natural Sciences and Mathematics::541: Physical #Technology::620: Engineering::620.1: Engineering Mechanics and Materials Science::620.11: Engineering Materials #Theoretical #liquid crystal nanocomposites #mesoporous alumina #mesoporous silica #nanoconfinement #optical polarimetry #twist-bent nematics
paper · doi:10.15480/882.15924
Bent-core nematic liquid crystals exhibit unique properties, including giant flexoelectricity and polar electro-optic responses, making them ideal for energy conversion and electro-optic applications. When confined in nanopores, they can stabilize chiral nanostructures, enhance polar order, and enable defect-driven switching – offering potential in nanofluidics, sensing, and adaptive optics. The thermotropic ordering of the bent-core dimer CB7CB confined in anodic aluminum oxide (AAO) and silica membranes with precisely engineered cylindrical nanochannels – ranging from just a few nanometers to several hundred nanometers–is examined. These well-aligned nanochannels enable high-resolution polarimetry studies of optical anisotropy, revealing how geometric confinement affects molecular organization and phase behavior. Under weak confinement, CB7CB forms a layered heterophase structure, with nematic, splay-bent, and twist-bent heliconical phases likely arranged concentrically. As confinement increases, a Landau-de Gennes analysis shows that ordered phases are suppressed, leaving only a paranematic phase under strong spatial constraints. Remarkably, temperature-dependent changes in optical birefringence under confinement closely resemble those seen under applied electric fields, revealing a parallel between geometric and electro-optic effects. Overall, this work demonstrates how nanoconfinement allows one to systematically tailor the self-assembly and optical behavior of bent-core nematics, enabling novel functionalities in responsive and anisotropic materials.