Dissolved State of Atactic Polystyrene in Aromatic Solvents: Approaches through 1H NMR, FT-IR and Adiabatic Compressibility

Abstract

ABSTRACT:An attempt was made to interpret significant differences in thermodynamic parameters, including the concentration dependence coefficients Pt and p2 of the polymer-solvent interaction parameter X, Flory entropy parameter at infinite dilution 1/10 , Flory temperature 0, observed between atactic polystyrene (PS) in aromatic and aliphatic solvents by the characteristic features of the dissolved state of PS in aromatic solvents. For this purpose, 1 H NMR spectra were measured on PS/benzene, cyclohexane, toluene, and methylcyclohexane systems and the infrared spectra and adiabatic compressibility were determined for the former two solvents. In PS/aromatic solvents H,-, H 3-, and H4-phenyl proton peaks are shifted to a lower magnetic field than those in PS/aliphatic solvent, which was produced by hydrogenation of the aromatic solvent. The degree of solvation is slightly larger in benzene than in cyclohexane. The experimental results were explained only by the case where the PS phenyl ring was stacked in parallel to the solvent phenyl ring for PS/aromatic solvent systems. larger than those between CH and MCH for both CSP. From these analyses they concluded2 that the skelton structure of the solvent is a more important factor than the substituent group to the skelton, covering the thermodynamic interaction between the polymer and solvent, and that even if the solvents have similar molecular weights and almost the same molecular shapes, p 1 and p 2 differ remarkably depending on whether the solvent is aliphatic or aromatic. Table I was made from Table II