Studies on the Clathrate (δ) Form of Syndiotactic Polystyrene Crystallized by Different Solvents Using Fourier Transform Infrared Spectroscopy

Abstract

Amorphous syndiotactic polystyrene (sPS) was crystallized at room temperature in dichloromethane, chloroform, toluene, o -dichlorobenzene, and decalin (cis−trans) to form the clathrate structure (δ form) with respective solvent molecules. Room temperature FTIR spectra are compared for subtle differences, which arise due to the solvent for the first time. The absorbance bands in the regions 590−615, 920−950, and 1130−1400 cm -1 are identified to be sensitive to the solvent used for the compound formation. In-situ high-temperature Fourier transform infrared spectroscopic studies were made on these samples, and the spectra showed major changes when the γ form transformed into the α‘ ‘ form at ∼200 °C on heating; the bands due to the helical structure disappear, and bands corresponding to the zigzag conformation appear. On the other hand, the transition of the δ form into the γ form on heating above the glass transition temperature involves spectral changes in weak bands sensitive to the helical conformation.