Aqueous polymerization of methacrylamide initiated by KMnO₄/H₂C₂O₄ redox system

Abstract

The polymerization of methacrylamide initiated by potassium permanganate/oxalic acid redox system has been studied at 35 f 0.2"C in a nitrogen atmosphere. The rate of polymerization is independent of the activator (oxalic acid) concentration within the range 5.10-3to 10.10-3mole.1-1, except at very high (above 10.10-3mole.1--1) or at very low(be1ow 5 .lO-3 mole.1-1) concentrations of the activator. The rate varies linearly a t low monomer concentration (up t o 5.87.10-2 mole.1-1). The catalyst exponent decreases from nearly unity (0.91) to 0.66 with increase in concentration of the catalyst (KMnO4) probably due to participation of primary radicals in the termination of the growing chain. The addition of strong acid (HzSO4) within the range 5~10-4-15~10-4mole~l-~, shows a constant pH of 2.7 resulting in no change in initial rate. With activator alone (13zC204.2HzO), within the pH range 2.7 to 2.9 an optimum is observed. The initial rate increases with increase in polymerization temperature. The overall energy of activation as calculated from the ARRHENIUS plot has been found t o be 15.1 kcal.mole-1 within the temperature range 30-50°C.Organic solvents (water miscible only) depress the initial rate and the maximum conversion. Small amounts of neutral salts (KCl and NazSOd), however, show no appreciable effect on the polymerization rate, but small amounts of manganous salts (MnS04) can increase the initial rate to a considerable extent. High concentrations of MnS0.q result in termination of the growing chain. A complexing agent, Na2F2, decreases the initial rate but increases the maximum conversion. Introduction of fresh catalyst at intermediate stages of polymerization increases both the rate of the reaction and the conversion. ZUSAMMENFASSUNG:Die mit dem Redoxsystem Permanganat/Oxalsaure ausgeloste Polymerisation von Methacrylamid unter Stickstoff wurde bei 35 i 0,2OC untersucht. Die Polymerisationsgeschwindigkeit ist im Bereichvon 5.10-3 bis 10.10-3 mol.Z-1vonder Aktivator(Oxa1saure)konzentration unabhangig. Hiervon ausgenommen ist der Bereich sehr hoher (iiber 10 mol. I-1) oder sehr niedriger (unter 5 .10-3 mo1.Z-1) Alrtivatorkonzentration. Die Geschwindigkeit ist bis zu 5,87.10-2 mol. Z -1 der Monomerkonzeutration proportional. Der Katalysatorexponent nimmt von nahezu eins (0,91) bis auf 0,66 mit zunehmender Katalysator-(KMn04-)konzentration ab, da moglicherweise Primarradikale am Abbruch der wachsenden Kette teilnehmen. Das Zugeben einer starken Saure (HzSO4) innerhalb 5.10-4-15.10-4 mo1.I-1 ergibt einen koustanten pH-Wert von 2,7 und bewirkt keine Anderung der Startgeschwindigkeit. Mit dem Aktivator (IIzC204.2 HzO) allein wird im pH-Bereich von 2,7 bis 2,9 ein Optimum beobachtet. 195 C;. S. MISRA and C. V. GUPTA Die Startgeschwindigkeit wachst mit zunehmender Polymerisationstemperatur. Die gesamte Aktivierungsenergie berechnet sich im Bereich von 30-50 "C aus der Auftragung nach ARRHENIUS zu 15,l kcal.mo1-1. Organische Losungsmittel (nur solche, die mit Wasscr mischbar sind) vermindern die Startgeschwindigkei...

Aqueous polymerization of methacrylamide

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Polymerization kinetics of methylmethacrylate by oxidation: Reduction system using cerium(IV)/lactic acid in aqueous medium

“…Further the interchain hydrogen bonding interlocking the polymer chain is not rigid, and therefore the tendency of mutual termination of the polymer chain increases. 58,59 Effect of surfactants on the rate of polymerization…”

Studies on Vinyl Polymerization: Polymerization of Methyl Methacrylate by Permanganate-Malonic Acid Initiator System

“…It cannot alone initiate polymerization of vinyl monomers in aqueous medium, but when coupled with a suitable organic substrate (reducing agent), it acts as a powerful initiator for the polymerization of vinyl monomers, e.g., acrylic acid, methacrylic acid, acrylonitrile, methyl acrylate, methyl methacrylate, acrylamide. A large number of organic substrates, e. g., oxalic acid, citric acid, tartaric acid, isobutyric acid, glycerol, and ascorbic acid, have been coupled with permanganate by different groups of workers [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] to utilize them as the initiator systems. Palit et al [l,21,Misra et al [3,41, Konkhim et al [7], and Matsuzawa et al [8] have extensively studied the polymerization of different vinyl monomers by the permanganate-oxalic acid redox system.…”