Calorimetric study of nematic prewetting

PACS. 61.30.Gd – Orientational order of liquid crystals; electric and magnetic field effects on order. PACS. 64.70.Md – Transitions in liquid crystals. PACS. 68.08.Bc – Wetting. Abstract. – We report specific-heat measurements for a series of liquid crystals imbedded in a porous cylindrical geometry. Above the nematic-to-isotropic transition and dependent on nematic width (or chain length), the specific heat shows a small peak. In analogy to known ellipsometry results, the peak is believed to be the signature of a nematic prewetting transition. The behavior of liquid crystals (LC) at interfaces has been extensively researched due to the fundamental phenomena present and the possible impact on technological applications. Typical studies have determined the orientational anchoring and/or wetting behavior of LC at solid substrates or at the air interface [1–3]. Using ellipsometry on planar LC films, Lucht et al. [4–6] investigated the wetting behavior at the free surface, above the nematic (or smectic-A) to isotropic phase transition for several LC series. Above the smectic-A–to–isotropic (AI) transition of non-polar compounds they observed either i) complete wetting, or ii) partia