Effect of deuteration on the alkyl chain dynamics in the reentrant liquid crystal CBOBP

Abstract

Deuterium NMR experiments were carried out for the reentrant liquid crystal CBOBP, (4-cyanobenzoyloxy-[4-octylbenzoyloxy]-.p-phenylene, and the chain-deuterated analog, CBOBP-d17. Significantly different dynamic behaviors were found between the protonated and deuterated alkyl chains. The deuterated chain exhibits distinctly higher orientational order in the reentrant nematic and the smectic A1 phases. A mechanism of the reentrant phase transition is discussed on the basis of the mass effect on the chain dynamics and the phase transition temperatures.