Phosphonic acid esters as thermally latent initiatiors: Initiation process in the polymerization of glycidyl phenyl ether

Abstract

The initiating species of phosphonic acid esters serving as thermally latent initiators was investigated in the cationic polymerization of glycidyl phenyl ether (GPE). O,O-Di-t-butyl phenylphosphonate (1 H) dissociated into phenylphosphonic acid and isobutene on heating to 150°C. 2H NMR spectroscopic study was carried out to examine the alkyl initiating species in the cationic polymeriaztion of GPE with O,O-di-t-butyl-d9 phenylphosphonate (1 D) in the presence of ZnCl2. A signal based on the t-butyl-d9 group was observed in the obtained polymer. The cationic polymerization of GPE with phosphonic acid was carried out to examine the proton initiating species at 170°C. GPE was converted quantitatively to the corresponding. It was suggested that both the alkyl cation and the proton serve as the initiating species in the cationic polymerization of GPE.