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THE ROLE OF HYDROGEN BONDING FOR INITIATION OF CHIRALITY, DENDRITES AND PHYSICAL GEL IN NEMATICS WITH SHORT RANGE SMECTIC C ORDER

B. Katranchev1,* , H. Naradikian1, M. Petrov1

Affiliation

  1. Laboratory “Optics and Spectroscopy”, Institute of Solid State Physics, Bulgarian Academy of Sciences, 72, Tzarigradsko Chaussee Blvd, 1784 Sofia, Bulgaria

Abstract

The transition from an achiral (racemic) to a chiral liquid crystal (LC) state is studied on microscopic and macroscopic levels. The induced chirality in achiral LC (4,n-alkyloxybenzoic acids – n-OBA, n = homologue number) is explained by symmetry lowering of the liquid crystal system due to breaking of the hydrogen bonds (the transformation of the closed dimers in open dimers) caused by temperature or surface action variations. An oriented dendrite texture appearing at a definite temperature in the nematic phase of 7-OBA and 8-OBA, aligned by rubbed polyimide, is reported. We suggest a possible mechanism for the dendrite growth. A new supramolecular compex: n-OBA and 4-hydroxypyridine (HOPY) is investigated using FT far-IR spectroscopy and polarization microscopy. A mechanism of the complex induction is suggested..

Keywords

Dendrites, Chirality, Dimers, Polyimide coatings.

Submitted at: Dec. 9, 2004
Accepted at: Jan. 26, 2005

Citation

B. Katranchev, H. Naradikian, M. Petrov, THE ROLE OF HYDROGEN BONDING FOR INITIATION OF CHIRALITY, DENDRITES AND PHYSICAL GEL IN NEMATICS WITH SHORT RANGE SMECTIC C ORDER, Journal of Optoelectronics and Advanced Materials Vol. 7, Iss. 1, pp. 273-276 (2005)