Low Temperature Initiation by 3-Mercaptopropionic Acid-Ce(IV) or -KMnO₄Redox System for Polymerization of Acrylamide Monomer

Polymerization of acrylamide initiated with Ce(IV)- and KMnO4–mercaptosuccinic acid redox systems in acid-aqueous medium

“…It was reported that H 2 SO 4 was used to increase the solubility of the oxidant and to prevent the hydrolysis of the oxidant. Moreover, the redox reaction between mercaptosuccinic acid and Ce(IV) or KMnO 4 salt takes place in acetic medium [30][31][32][33][34]. After polymerization was completed, the solution was poured into an excess of acetone to precipitate the raw polymer.…”

Swelling properties of acrylamide-N,N’-methylene bis(acrylamide) hydrogels synthesized by using meso-2,3-dimercaptosuccinic acid-cerium(IV) redox couple

“…These parameters are: the molar ratios of acrylamide/ cerium(IV) sulfate (n AAm /n Ce(IV) = 100 and 200) at constant crosslinker and acid concentrations, the concentration of sulfuric acid (C H 2 SO 4 = 0.0125 and 0.025 mol/l) at the n AAm /n MBAA = 40 and the molar ratios of acrylamide to N,N′-methylene bis(acrylamide) for different acid and initiator concentrations. The radical generation in the redox reaction of meso-2,3-dimercaptosuccinic acid and cerium(IV) sulfate in acid-aqueous medium is supposed to occur by one electron transfer from meso-2,3-dimercaptosuccinic acid to Ce(IV) according to the reactions given in Figure 1 as reported in the literature [18][19][20][21][22]. Because of low S-H bonding energy, the formation of free radicals in reaction I in Figure 1 is more likely than other reactions to initiate crosslinking polymerization of acrylamide and N,N′methylene bis(acrylamide) and oxidative termination of polymer radicals is also possible by ceric ions [18,20,21].…”

“…The radical generation in the redox reaction of meso-2,3-dimercaptosuccinic acid and cerium(IV) sulfate in acid-aqueous medium is supposed to occur by one electron transfer from meso-2,3-dimercaptosuccinic acid to Ce(IV) according to the reactions given in Figure 1 as reported in the literature [18][19][20][21][22]. Because of low S-H bonding energy, the formation of free radicals in reaction I in Figure 1 is more likely than other reactions to initiate crosslinking polymerization of acrylamide and N,N′methylene bis(acrylamide) and oxidative termination of polymer radicals is also possible by ceric ions [18,20,21]. In previous investigations, it is described that the formation of radicals on carboxyl groups may be possible [18][19][20][21][22].…”

“…Because of low S-H bonding energy, the formation of free radicals in reaction I in Figure 1 is more likely than other reactions to initiate crosslinking polymerization of acrylamide and N,N′methylene bis(acrylamide) and oxidative termination of polymer radicals is also possible by ceric ions [18,20,21]. In previous investigations, it is described that the formation of radicals on carboxyl groups may be possible [18][19][20][21][22]. However, the radical formation on carboxyl groups may appear less than that of the other radical formation reactions given in Figure 1, as the formation of free radicals on carcoxyl groups requires more energy.…”

“…However, ceric saltorganic reducing agent containing thiol functional group or groups are also new sources to initiate copolymerization of vinyl monomers at low tem-peratures. When reducing agent with thiol functional group is used in redox system of ceric saltorganic reducing agent, the formation of -S. radical is energetically most favorable due to low S-H bonding energy to initiate copolymerization of gel particles in acid-aqueous medium at lower temperatures [18][19][20][21][22][23]. The swelling of polymeric networks is influenced by the composition of the polymer i.e.…”