Alternating‐Current‐Field Induced Cholesteric–Nematic Phase Transitions

The Journal of Chemical Physics (Impact Factor: 3.12). 12/1969; 51(12). DOI: 10.1063/1.1671961

ABSTRACT In order to determine whether interaction between the permanent or the induced molecular dipole moments of a cholesteric liquid crystal and an applied electric field is responsible for inducing a transition to a nematic phase, ac‐field measurements were performed. In a mixture of cholesteryl chloride and cholesteryl myristate, phase transitions can be induced by an ac field of a frequency up to a threshold value fpt;fpt is approximately equal to the relaxation frequency for rotation of cholesteryl chloride molecules around a short molecular axis which has recently been determined by dielectric measurements. A relation between the rms field and fpt is derived and experimentally verified. The absence of ferroelectric ordering in the induced and aligned nematic phase is demonstrated.

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