Dielectric and orientation effects of ‘classical’ and supramolecular liquid crystals self-assembly

ABSTRACT

Fragments of phase diagrams of binary systems containing 4-pentyloxy-4ʹ-cyanobiphenyl (5OCB) and 4-(ω-hydroxyalkyloxy)-4ʹ-cyanobiphenyl (HO3OCB, HO6OCB and HO9OCB) were obtained. The temperature range expansion of the nematic phase at mixing of the components was established. The dielectric and optical properties of binary mixtures were studied. A significant increase in the dielectric anisotropy was observed when the ‘classical’ liquid crystal (LC) was mixed with supramolecular HOnOCB. From the data on birefringence and the ¹H NMR spectra, temperature dependences of the orientational order parameter of the ‘classical’ LC + supramolecular LC systems were obtained. There is a good agreement between S values obtained by independent methods. The invariability of the order parameter at mixing 5OCB with HO3OCB and HO9OCB and some growth in systems containing HO6OCB were observed. On the basis of quantum chemical calculations, the analysis of the most probable types of components association in the systems 5ОСВ + HOnOCB was carried out. From the analysis of Kirkwood correlation factors, the main role of competition between the two mechanisms of intermolecular interaction was revealed.

ABSTRACT

KEYWORDS:

• Cyanobiphenyls
• nematic phase
• dielectric anisotropy
• birefringence
• order parameter
• NMR spectroscopy
• hydrogen bond
• self-assembly

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The study was carried out as a part of State Task of the Ministry of Education and Science of the Russian Federation (project 4.1929.2017/4.6 and 4.7305.2017/8.9 - NMR experiment).