Ferrocene/ferrocenium Redox shuttling: peroxide decomposition catalysis applied to vinyl monomers polymerization under suspension conditions
Résumé
Ascorbic acid derivatives in combination with ferrocenyl-based activators in catalytic amounts, referred to as kickers, are described as powerful redox systems to promote the decomposition of organic peroxides into radicals for the polymerization of vinyl monomers under suspension conditions. According to the nature of both the vinylic monomer and the peroxide, the initial polymerization rates can be improved by a factor up to 8. In the presence of ferrocene/ascorbyl palmitate kicker, the overall polymerization time of VC was reduced from 3 to 2 h under industrial conditions. However, crusting during polymerization as well as yellowing of PVC upon thermal tests were observed. The first problem was solved by changing the surfactant, while optimizing the injection mode of the kicker improved the efficiency of the process without affecting the quality of the resulting PVC. This study demonstrates the effectiveness of ferrocene-based kickers in improving the polymerization of vinyl monomers under suspension conditions.