Studies on the kinetics and initiation mechanism of acrylamide polymerization using persulfate/aliphatic diamine systems as initiator

The effects of various aliphatic diamines on vinyl polymerization using ammonium persulfate as initiator were studied. It was found that diamines with two amino groups separated by an ethylene unit possess higher promoting activities than those with two amino groups linked by other α,ω‐alkylene units such as methylene or propylene. The promoting activities of diamines on vinyl polymerization are in the order: tertiary diamine > secondary diamine > primary diamine. The methyl group is a preferred substituent at the amino groups of the diamine, being faster oxidized by persulfate (to produce the dialkylaminomethyl free radical) than the α‐methylene groups. The primary free radicals produced through redox‐reaction of persulfate and aliphatic diamines were studied using the spin trapping technique and ESR spectroscopy. An initiation mechanism of persulfate/aliphatic diamine systems is proposed.