Studies of molecular dynamics and non-isothermal crystallization process of 4-n-butyloxybenzylidene-4′-n'-octylaniline (BBOA) liquid crystal under two dimensional nano-confinement

Abstract

The impact of confinement imposed by cylindrical pores of alumina matrix on the molecular dynamics and phase behavior of BBOA liquid crystal was examined by a combination of Broadband Dielectric Spectroscopy (BDS), Differential Scanning Calorimetry (DSC) and Fourier-Transform Infrared Spectroscopy (FTIR) methods. The phase transition temperatures as a function of inverse pore diameter show linear dependence. The BDS studies revealed new relaxation processes related to gradual paranematic-to-nematic transition in nanopores. Special emphasis is given to the influence of spatial constraints on the non-isothermal crystallization process upon cooling. Furthermore, the analysis of temperature dependent IR spectra of BBOA pointed out that the band ascribed to vibration of methylene group ν s (CH 2 ) changes abruptly at crystallization temperature in bulk whereas a continuous temperature evolution of the ν s (CH 2 ) band shift upon crystallization was observed under confinement. • Phase behavior of a liquid crystalline material in spatial restriction • Inter- and intra-molecular dynamics under nanometric confinement • Non-isothermal crystallization of a liquid crystal in pores