Phase Behavior of Binary Mixtures of a Liquid Crystal and Methane

Phase diagrams of binary systems of four different liquid crystals with different polarity and CH4 are investigated experimentally in this study. The solubility of CH4 in liquid crystals has not been studied before. The liquid crystals used were 4-ethyl-4'-propylbicyclohexyl, 4-pentylcyclohexyl-4'-benzonitrile, 4-pentyl-4'-cyanobiphenyl, and 4-pentyloxy-4'-cyanobiphenyl. The concentration of the methane used was 0.01 wt %. The phase diagrams were studied in the temperature range of (295 to 365) K and up to 13 MPa. The phase equilibria studied were the three-phase equilibria nematic + isotropic + gas, smectic + isotropic + gas, and the two-phase equilibria isotropic + gas <-> isotropic, nematic + isotropic <-> isotropic, nematic <-> nematic + isotropic, and smectic + isotropic <-> isotropic. The main conclusion of this study is that increasing the polarity of the solvent leads to a lower solubility of CH4.