It is well known that a relatively large Kerr effect in the isotropic phase of nematic liquid
crystals (NLCs) is related to the existence of short-range ordering (SRO). Thus, the
conversion of the long-range ordering (LRO) behavior in the nematic phase to the SRO in
the isotropic phase of NLCs can characterize the nonlinear electro-optic Kerr effect. To
show conversion from LRO to SRO, we employ an empirical solvent polarity scale (
).
Interestingly,
originates from the solvatochromic polarity (SP) parameters, which
demonstrates the quantitative value for describing the molecular interaction in each
temperature point, even in the isotropic phase of NLCs. Our results show that the higher
value leads to a larger Kerr constant (B) owing to the larger short-range molecular
interaction between rigid rod-like NLCs. To demonstrate a linear relationship of the B value
with the
and SP parameters, a new correlation is introduced for the first time. Our
investigations and newly introduced parameters strongly indicate that short-range molecular
interactions still exist in the isotropic phase of NLCs, even when the macroscopically
observable LRO behaviors disappear.
