Polymerization of N,N′-methylenebisacrylamide initiated by two new redox systems involving acidic permanganate

Two new redox systems, viz. KMnO₄ with ethyleneglycol and KMnO₄ with thioglycollic acid, have been used as initiators for the polymerization of the divinyl monomer, N,N′-methylenebisacrylamide. The initiating radical is formed when a monomer-Mn³⁺ complex interacts with the redox complex. An intramolecular cyclization prior to propagation is involved in the mechanism suggested to explain the kinetics. The higher rate of polymerization for this monomer, when compared with acrylamide and methacrylamide, gives added evidence for this new type of propagation.     

Kinetics of Cyclopolymerization of N,N′-Methylenebisacrylamide Initiated by Redox Couples with Mn(III). Part III

Redox-initiated free-radical cyclopolymerization of the nonconjugated divinyl monomer N,N′-methylenebisacrylamide was studied at 25–40°C, involving trisacetatomanganese(III) dihydrate as oxidant with four different reductants, methyl ethyl ketone (2-butanone), cyanoacetic acid, malic acid, and thiomalic acid. While the general mechanistic sequence is the same, the modes of termination are different in these cases. Because the reactivities of the different free radicals from the four redox pairs are different, the kinetic order with respect to the monomer, oxidant, and reductant differ considerably in magnitude. The kinetic and thermodynamic parameters were calculated.     

Kinetics of acid catalyzed and Ag(I) catalyzed decomposition of peroxodisulfate in aqueous medium

The mechanism of acid catalyzed decomposition of peroxodisulfate, (S₂O) in aqueous perchlorate medium involves the hydrolysis of the species H₂S₂O₈ and HS₂O and the homolysis of the species H₂S₂O₈, HS₂O and S₂O at the O? O bond. The overall rate law when 1.4M > [HClO₄] > 0.1M is The constants k′ and k″ contain the hydrolysis and homolysis rate constants of HS₂O₈^? and H₂S₂O₈, respectively. With added Ag(I), the acid catalyzed and Ag(I) catalyzed reactions take place independently. Ag(I) catalyzed decomposition appears to involve the species AgS₂O (aq).     

Synthesis and characterization of some halogen-containing poly(esterurethane)s

A series of halogen-containing poly (esterurethane)s was synthesized from the prepolymers, i.e., hydroxy-terminated polyesters containing chlorine and fluorine and the diisocyanates such as toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI). Polyesterification of halogenated phthalic anhydride with an excess of diols such as ethylene glycol, 1,2-propanediol, and 1,4-butanediol in the presence of trifluoroacetic anhydride (TFAA) was carried out to prepare prepolymers. The prepolymers and the poly (esterurethane)s were characterized by infrared (IR), ¹H nuclear magnetic resonance (NMR), viscosity, end-group analysis, solubility and thermal analysis namely thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Kinetics of thermal degradation was also studied. Resistance of the polymers to alkaline agents and combustion was also tested.     

Polymerization of methyl methacrylate with cobalt acetylacetonate-diethyl zinc catalyst system

Polymerization of methyl methacrylate was studied with a cobalt acetylacetonate-diethyl zinc catalyst initiator system in benzene medium at 40°C. When the stoichiometric ratio of Zn/Co is 2, the activity for polymerization is found to be maximum. The structure of the obtained polymethyl methacrylate is compared with that obtained using a free-radical initiator such as benzoyl peroxide. The structure of polymer and the M?_w/M?_n values indicate that cobalt acetylacetonate-zinc diethyl system has pronounced free-radical characteristics. A suitable mechanism is proposed from the kinetic studies. © 1995 John Wiley & Sons, Inc.     

Kinetics of polymerization of N,N-methylenebisacrylamide initiated by KMnO4-H2C2O4 redox system

A kinetic study of the gel free polymerization of the divinyl monomer N,N′-methylenebisacrylamide has been made using permanganate-oxalic acid system as redox initiator; R_p is proportional to [monomer]², [KMnO₄] and [H₂C₂O₄]⁰. A cyclopolymerization mechanism is proposed. A complex between monomer and Mn³⁺ participates, in addition to the complex [Mn(HC₂O₄)₂]⁺.     

Peroxo salts as initiators of vinyl polymerization—2. Kinetics of polymerization of acrylic acid and sodium-acrylate by peroxodisulphate in aqueous solution—effect of pH and Ag+ catalysis

Results on the rate of polymerization of acrylic acid by S₂O^2?₈ ion in alkaline and acid conditions are presented. R_p depended upon $\text{[S}{}_2\text{O}{}^{\mathrm{2?}}{}_8\text{]}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and $\text{[monomer]}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ both in acid and alkaline solutions. The influence of ionic strength, the effect of pH on R_p and the catalytic effect of Ag⁺ and Cu²⁺ on the system have been discussed. Suitable mechanisms are proposed.