Novel Peroxide-Free redox initiator based on Saccharin/Electron Donor/Copper salt for radical polymerization

Abstract

In this work, a peroxide-free redox initiating system for radical polymerization of acrylate is suggested, based on the combination of saccharin, aromatic amine and copper salt. Free radical redox polymerization was investigated through differential scanning calorimetry (DSC), highlighting the efficiency of the redox initiating system. The role of the different components was studied mainly through liquid chromatography-coupled mass spectrometry (LC-MS), evidencing the involvement of aminoalkyl radical as initiating species. When p-toluenesulfonate is added as accelerator, the corresponding radical, as well as the oxygenated derived one, were found to act also as initiating radical. The oxidation state of the copper catalyst during the reaction is studied by UV–visible spectroscopy experiments, using bathophenanthroline as a probe for the involvement of Cu(I). From these experiments, a mechanism is proposed to account for the initiation reaction.