New Generation Kickers Based on Sulfinate Reducing Agents for the Synthesis of Polyvinyl Chloride by Free Radical Suspension Polymerization

A new family of organophilic sulfinate reagents, combined with catalytic amounts of ferrocene (Fc), was developed to improve peroxide decomposition in the radical suspension polymerization of vinyl chloride. More specifically, α-aminomethanesulfinate derivatives, bearing dicyclohexylammonium counterions, were designed to increase solubility in the monomer phase and support efficient Fc/Fc + redox cycling after peroxide reduction. Used with Fc, these reducing agents, collectively called a “kicker”, significantly accelerated polymerization under industrially relevant conditions with (2-ethylhexyl)peroxydicarbonate (EHP), shortening the time to reach 70% conversion by up to 28% compared with a reference run without kicker. Among the tested compounds, Fc/ 7 DCyA gave the best balance between activity and process control, enabling fast polymerization while maintaining suspension stability and limiting excessive heat release. The improved performance mainly came from better solubility and phase transfer, and the PVC properties, including particle size and thermal stability, remained unchanged. The strategy was also effective with lauroyl peroxide (LPO).