Effect of sulfonation on the crystallization behaviour of syndiotactic polystyrene

Syndiotactic Polystyrene (sPS) was sulfonated to different levels in a mixture of 1,1,2-trichloroethane and chloroform. Sulfonation levels were determined by nonaqueous titrations using phenolphthalein indicator. Thermal properties of sulfonated sPS (SsPS) ionomers depend on the sulfonation level. Incorporation of sulfonic acid groups in to the syndiotactic polystyrene backbone was found to affect the crystallization behavior of sPS. DSC data indicated that the melting temperature (T-m), heat of fusion, crystallization temperature (T-c), crystallization rate and degree of crystallization were lowered by the incorporation of sulfonic acid group on the syndiotactic polystyrene backbone. Thermal and FIR data indicated that the sulfonic groups did not enter into the crystal lattice but remained in the amorphous phase.