Magnetic hybrid materials in liquid crystals

Abstract

The integration of nanoparticles with magnetic, ferroelectric or semiconducting properties into liquid crystals (LCs) has attracted great interest both for fundamental investigations and for technological applications. Here, an overview of hybrid materials based on magnetic nanoparticles (MNPs) and thermotropic LCs is given. After a general introduction to thermotropic LCs and LC-MNP hybrid materials, various preparation methods established by us are presented. The synthesis of shape-(an)isotropic MNPs, their functionalization by tailored (pro)mesogenic ligands with linear or dendritic structures and their integration into LC hosts are discussed. The characterization of the MNPs, (pro)mesogenic ligands and resulting MNP-LC hybrid materials is described to show the influence of MNP functionalization on the MNP-LC interactions including aspects such as colloidal stability and structuring in the LC host. Overall, we show that the physical properties of the hybrid material are significantly influenced not only by the MNPs (i.e., their size, shape and composition) but also by their surface properties (i.e., the structure of the (pro)mesogenic ligands).

Magnetic Tilting in Nematic Liquid Crystals Driven by Self‐Assembly

“…The transition from the isotropic to the smectic A‐phase takes place at T(SmA‐I) = 88.2 °C, while the crystalline phase is formed at T(Cr‐SmA) = 88.0 °C. [ 20 ] The nature of the ligand critically influences the coupling to the surrounding LC host. A ligand exchange reaction of 4.6 nm CFO‐MNPs with a dendron yielded dendronized MNPs (Dend‐MNPs).…”

Rapid, label-free and low-cost diagnostic kit for COVID-19 based on liquid crystals and machine learning

“…When an array of liquid crystals (LC) is placed between two crossed polarizers, the presence of an external material in their vicinity can make the LC molecules reorient according to their proximity to the different parts of the material. As LCs are anisotropic in their natural state ( Li and Alivisatos 2003 ; Woltman et al, 2007 ; Hähsler et al, 2020 ; Prakash et al, 2020 ), their reorientation due to the external material leads to the appearance of specific patterns on the surface of one polarizer when light is emitted to the sample from the side of the other polarizer. The pattern can be recorded and analyzed in order to infer the composition of the external material.…”

Method of Molecular Parameters for Columnar Mesomorphism Prediction of Tristriazolotriazines

“…Создание новых наноматериалов на основе жидких кристаллов (ЖК) для электронных и оптоэлектронных устройств (солнечных батарей, полевых транзисторов, светодиодов, дисплейной оптики, квантовых компьютеров и др.) является актуальной областью исследований для более эффективного практического использования [1][2][3][4][5]. Если каламитные ЖК уже нашли достаточно широкое применение в современных нанотехнологиях, являясь, например, ключевыми элементами ЖКдисплеев [6][7][8], то использование дискотических мезогенов (ДМ) в этой области все еще находится на начальной стадии развития [9][10][11][12].…”