Atom transfer radical polymerization of styrenesulfonic acid sodium salts (SSNa) in aqueous phase

Aqueous ATRP of SSNa has been investigated in the presence of initiator, 2-bromo-2-methylpropionate (1), mediated with Cu(I)Br/bpy. When using water only as a polymerization solvent, some deviations from the living behaviors were observed, including a bimodal molecular weight distribution. It was found that the competitive coordination effect of water could be suppressed by using Cu(II)Br or variation of polymerization solvent. The addition of Cu(II)Br with the ratio of Cu(l)/Cu(II)= I was found to give the optimum results with 92% conversion achieved in approximately 60 min, leading to a polymer with a molecular weight close to the theoretical with a polydispersity index=1.20. Using mixture of. water and methanol with the ratio of water/methanol=30/20 wt% also suppressed the formation of the high molecular weight fraction and more than 95% conversion was achieved in 80 min. SEC of the resulting polymer was monodisperse with a polydispersity index =1.21.