The unique physical properties of the hydrogen bonded in dimers liquid crystals

INERA Workshop 2016: Membrane and Liquid Crystal Nanostructures

Petrov, M.^1 ; Katranchev, B.^1 ; Rafailov, P.M.^1

Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., Sofia

1784, Bulgaria^1

关键词: Aromatic carboxylic acids;    Cholesteryl benzoate;    Ferroelectric phasis;    Ferroelectric smectic;    Intermolecular hydrogen bonds;    Liquid crystalline;    Structure formations;    Supramolecular complexes;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/780/1/012012/pdf
DOI  :  10.1088/1742-6596/780/1/012012

来源: IOP

【 摘 要 】

The dimerization of aromatic carboxylic acids, is the base of the structure formation of hydrogen bonded in dimers liquid crystals (HBDLCs), that exhibit non-conventional mesomorphism. The structural units of these LCs are amphiphilic-type molecules, which after suitable functionalization, induce supramolecular complexes, nanocomposites based on HBDLCs. The liquid crystalline character of the nanocomposites strongly dependent on intermolecular hydrogen bonds between symmetric, where the H-donors and H acceptors are contained in similar and non-symmetric HBDLCs, where the H-donors and H acceptors are contained in unlike molecules. The strength and non-covalent character of the hydrogen bonds provides both sufficient HBDLCs complex stability and bonding flexibility with a possibility to design and drive the supramolecular geometry. We investigated a series of nanocomposites produced by mixture of HBDLC (p-n-alkyloxybenzoic acid - nOBA), serving as matrices, with non-mesogenic (single walled carbon nanotubes - SWCNTs, hydroxypiridine - HOPY) and mesogenic (cholesteryl benzoate - ChB) nano-particles in various shapes and sizes. A set of new chiral ferroelectric phases were found in the nanocomposites, otherwise do not appearing in the pristine achiral HBDLCs materials. A molecular model of an unique low-temperature ferroelectric smectic phase C based on the molecular dimer ring symmetry reduction (bent dimer formation) towards to the lowest triclinic one is presented for both symmetric and nonsymmetric supramolecular liquid crystal complexes.