Sulfonation of poly(propylene) films with fuming sulfuric acid

Sulfonation is one of the most commonly used methods for the surface modification of polymers. In this study, the sulfonation of poly(propylene) (PP) films with fuming sulfuric acid has been investigated with the focus on the surface reaction. Analysis of the sulfonated PP films by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance (ATR) infrared spectroscopy, and chemical modification demonstrated the formation of C=C double bonds and sulfate groups in the sulfonation process. These results and a comparison with low-density polyethylene (LDPE) films led us to propose a new sulfonation mechanism involving hydride abstraction and the formation of beta-sultones.