Preferential solvation of the eutectic mixture of liquid crystals E7 in a polysiloxane

Blends of the nematic liquid crystal E7 and poly(methylphenylsiloxane) (PMPS) with molecular weight 120,000 g/mol are investigated by high performance liquid chromatography (HPLC) measurements. This study was prompted by observations made recently while analyzing the phase behavior of poly(siloxane)/E7 and poly(acrylate)/E7 systems. A remarkable increase of the nematic to isotropic transition temperature TNI was found when polymer was added to the liquid crystal. Surprisingly, the increase of TNI was enhanced with the polymer concentration up to 80 wt%, where it reached its highest value. This behavior could be interpreted by invoking a preferential solvation of the constituents of E7 towards the polymer. The present investigation provides an evidence of this phenomenon using HPLC data.