Synthesis and characterization of polyacrylamides containing meso‐2,3‐dimercaptosuccinic acid end groups

Abstract

By using meso-2,3-dimercaptosuccinic acid-cerium(IV) sulfate and meso-2,3-dimercaptosuccinic acid-potassium permanganate redox systems, the polymerization reaction of acrylamide (AAm) monomer was examined in aqueous acidic medium at low temperatures. Water-soluble polyacrylamides bearing meso-2,3-dimercaptosuccinic acid end groups were synthesized using meso-2,3-dimercaptosuccinic acid as a reducing agent. The effects of parameters such as the molar ratio of acrylamide to initiator, temperature, polymerization time, and sulfuric acid concentration on the yields and molecular weights of polymers were investigated. The augmentation in initiator concentration resulted in a decrease in molecular weight but an increase in the yield of polymers. The increase in reaction temperature from 20 to 60 • C led to a decrease in the yield from 56.80% to 20.58%. Ce(IV) and Mn(VII) ions are reduced to Ce(III) and Mn(II) ions in the polymerization reaction and the synthesized acrylamide polymers containing meso-2,3-dimercaptosuccinic acid end groups can absorb these ions at the end of the polymerization reaction. Ultraviolet-visible and atomic absorption measurements of polymer solutions were performed to indicate complexation between polyacrylamide and Ce(III) ions or Mn(II) ions. C

3‐Mercaptopropionic Acid–Ce(IV) Redox Couple for Preparing Cross‐Linked Gels with Moderate Swelling Ratios

“…The radical generation in the redox reaction of MPA and cerium(IV) sulfate in acid aqueous medium is believed to occur by one-electron transfer from MPA to Ce(IV) according to the reactions given in Scheme 1 as reported in the literature. [25][26][27][28][29][30]32,37 Because of low S H bonding energy, the formation of free radicals in reaction (I) in the Scheme 1 is more likely than other reactions to initiate crosslinking polymerization of AAm and MBAA, and oxidative termination of polymer radicals is also possible by ceric ions. 25,27,28,30,32,37 In previous investigations, it is described that the formation of radicals on carboxyl groups may be possible.…”

“…[25][26][27][28][29][30]32,37 Because of low S H bonding energy, the formation of free radicals in reaction (I) in the Scheme 1 is more likely than other reactions to initiate crosslinking polymerization of AAm and MBAA, and oxidative termination of polymer radicals is also possible by ceric ions. 25,27,28,30,32,37 In previous investigations, it is described that the formation of radicals on carboxyl groups may be possible. [25][26][27][28][29][30][31][32][33]37 However, the radical formation on carboxyl groups may appear less than that of the other radical formation reactions given in Scheme 1, due to necessity of higher energy for the formation of free radicals on carboxyl groups and formation of ionization of carboxyl groups in an aqueous medium.…”

“…25,27,28,30,32,37 In previous investigations, it is described that the formation of radicals on carboxyl groups may be possible. [25][26][27][28][29][30][31][32][33]37 However, the radical formation on carboxyl groups may appear less than that of the other radical formation reactions given in Scheme 1, due to necessity of higher energy for the formation of free radicals on carboxyl groups and formation of ionization of carboxyl groups in an aqueous medium.…”

“…[19][20][21][22][23][24] A ceric salt-organic reducing agent containing thiol, hydroxyl, carboxyl, and amine functional groups can be used for polymerization and copolymerization of vinyl monomers. [25][26][27][28][29][30][31][32][33][34][35][36] However, ceric salt-organic reducing agents containing the thiol functional group or groups are new sources to initiate copolymerization of vinyl monomers at low temperatures. When a reducing agent with the thiol functional group is used in a redox system of the ceric salt-organic reducing agent, the formation of the 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.…”

“…When a reducing agent with the thiol functional group is used in a redox system of the ceric salt-organic reducing agent, the formation of the 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. [25][26][27][28][29][30]32 In this study, the 3-mercaptopropionic acid-Ce(IV) redox system was used to synthesize the cross-linked polymer of AAm with MBAA in acid aqueous medium. The effects of parameters such as molar ratios of AAm to MBAA, AAm to cerium(IV) sulfate, and the concentration of sulfuric acid were investigated.…”