[Research on a new side-chain liquid crystalline polysiloxane as stationary phase for capillary column gas chromatography].

A new stationary phase, side-chain liquid crystalline polysiloxane, was obtained and used in capillary column gas chromatography. Two kinds of side-chain polysiloxane, PSI5 and PSI6, were characterized by polarized light microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction and proved to be smectic phase Sc. Two fused-silica capillary columns (0.25 mm i.d.) were coated with 5 g/L solutions of PSI5 and PSI6 in dichloromethane by the static method, named column 15 and column 16. Numbers of theoretical plate were 1,598/m-2,423/m (I5) and 3,191/m-4,235/m (I6) for anthracene at 200 degrees C-240 degrees C. These columns showed wide operation temperature range (I5: 50 degrees C-200 degrees C; I6: 100 degrees C-260 degrees C), outstanding thermostability and weak polarity. These columns exhibited unique selectivity for many organic compounds, especially positional isomers. For example, the mixtures of anthracene, phenanthrene and fluorene were well separated on column I5 and I6; dimethyl benzene isomers were well separated on column I5, but they were not separated on column I6; dimethyl phenol isomers were well separated on column I5, but they were not wholly separated on column I6. The different selectivities of these columns are mainly due to the different chemical structures.