Structure and properties of the mesophase of syndiotactic polystyrene

The clathrated syndiotactic polystyrene (sPS) membranes were cast from the sPS solution of either ortho or meta or para-chlorotoluene isomer [(o, m, p)-CT] and sPS-(o, m, p)-CT (A-M) mesophase membranes were prepared by stepwise solvent extraction method. The formation of clathrate and mesophase were confirmed by IR, TGA, DSC and wide angle X-ray diffraction (WAXD) analyses. Among the isomers the p-CT (A-M) mesophase membrane was used for the sorption studies. The p-CT (A-M) mesophase membranes were immersed in mixed solution which includes different vol% of p-xylene (p-X) or chlorobenzene (CB) or 1,1,2-trichloroethane (TCE) or chloroform (CF) with 1 vol% of p-CT-methanol. The IR results confirmed that two solvents are sorbed in the molecular cavity of p-CT (A-M) mesophase membranes. The sPS-p-CT (A-M) mesophase membrane after immersed in equal concentrations of mixed solution, the relative absorbance (RA) of p-CT solvent peak is very high when compared with other solvents in the mixed solution and it is equal to the 1 vol% p-CT-methanol pure solution. The RA of p-CT decreased with increasing the concentration of other solvents in 1 vol% p-CT-methanol mixed solution. The DSC result revealed that two endothermic peaks are observed for lower concentrations of all the mixed solution in the temperature range between 85 and 120 °C and it confirmed that two clathrates were formed in the sPS membrane. The WAXD results showed that the (0 1 0) plane of the 2θ peak of p-CT (A-M) mesophase membrane gradually approached to that of the original clathrate of respective immersion solvents with increasing the concentration of immersion solvents in the 1 vol% p-CT-methanol mixed solution.