Pretransitional surface ordering and disordering of a liquid crystal

Using the evanescent-wave ellipsometry technique, we have observed the growth of a disordered liquid-crystal layer adjacent to a ${\mathrm{SiO}}_{\mathit{x}}$-coated surface near the nematic-isotropic transition. We have also observed the pretransitional growth of a planar-oriented liquid-crystal layer in the isotropic phase of the same system, with a negative orientational order parameter. Both behaviors can be explained quantitatively by the Landau–de Gennes theory.