Kinetics of polymerization of acrylic acid initiated by Mn3+–isobutyric acid redox system. II

The kinetics of redox -initiated polymerization of acrylic acid (AA) by the systerm Mn³⁺-isobutyric acid (IBA) in sulfuric acid was studied in the temperature range of 35–50°C. The overall rates of polymerization (R_p), disappearance of manganic ion (?R_m), and degree of polymerization (X _n), were measured with variation in [monomer], [Mn³⁺], [IBA], H⁺, μ, [Mn²⁺], and temperature. The polymerization is initiated by the organic free radical that develops from the Mn³⁺-isobutyric acid oxidation reaction. Two types of termination reactions, one by the metal ion (Mn³⁺) and the other by the MN³⁺-isobutyric acid complex are proposed to explain the kinetic results. The various rate parameters were evaluated an discussed.     

Homopolymerization of Ethyl Methacrylate

The kinetics of polymerization of ethyl methacrylate initiated by manganese (III) in sulfuric acid have been investigated. The overall rates of polymerization (R_p), disappearance of manganic ion (-R_m), and degree of polymerization (X _n) were measured with variation in [monomer], [Mn³⁺], [H⁺], μ, and temperature. Various rate parameters and thermodynamic parameters were evaluated and are discussed.     

Aqueous polymerization of acrylonitrile initiated by manganese(III) pyrophosphate-thiocyanate redox system: a kinetic study

Summary The kinetics of aqueous polymerization of acrylonitrile monomer (M) initiated by the Mn^III-KNCS redox system have been studied under deaerated conditions in the temperature range 26–40 °C at constant ionic strength. The overall rates of polymerization and the disappearance of Mn^III were determined. The polymerization was initiated by the free radicals arising from the Mn^III-thiocyanate redox reaction. The rate of polymerization was investigated at various concentrations of monomer and initiator. The effects of varying [Mn^III], [NCS^–], pH, total [P₂O _inf7 ^sup4– ], added [Mn^II], metal ions, ClO _inf4 ^sup– , Cl^– and SO _inf4 ^sup2– were examined. Dependence of the rate of polymerization on temperature was studied and activation parameters were computed from an Arrhenius plot. A suitable kinetic scheme consistent with the observed results is proposed and discussed.     

Polymerization of Methyl Methacrylate: Kinetics of the Reaction Initiated by the Mn(III)-1,2-Propanediol Redox System

Kinetics of polymerization of methyl methacrylate initiated by Mn³⁺/1,2-propanedlol has been investigated in aqueous sulfuric acid at the temperature range of 25–35°C. The rate of polymerization (R_p) and the rate of manganic ion disappearance (-R_Mn) have been computed. The effects of organic solvents, certain cationic and anionic detergents, added electrolytes on the initial rate of polymerization, and maximum conversion have been examined. Depending on the kinetic results, a reaction scheme has been suggested involving the formation of a complex between Mn³⁺ and the alcohol, which subsequently decomposed in an unimolecular step to generate the initiating free-radical which initiates polymerization and termination of the growing polymer chain by metal ion.     

Vinyl polymerization by cobaltic ions in aqueous solution: Part I. Polymerization of methyl methacrylate

Polymerization of methyl methacrylate initiated by cobaltic ions in perchloric, nitric and sulfuric acids was studied in the temperature range 15–25°C. In all three acids, water oxidation occurred as a side reaction. In HClO₄ and HNO₃ media monomer oxidation was shown to be an additional complicating feature. Rates of cobaltic ion disappearance, monomer disappearance, and chain lengths of polymers were measured with variations in [M], [Co³⁺], [H⁺], initially added [Co²⁺], and temperature. In HClO₄ and HNO₃ experimental results favored simultaneous initiation by Co³⁺ and CoOH²⁺ species, while in H₂SO₄, Co³⁺ ions alone were the active entities. An appropriate kinetic scheme to fit all the experimental observations is proposed. The various rate constants were evaluated.     

Polymerization of methyl methacrylate initiated by Mn(III)–glycerol redox system

The kinetics of thermal polymerization of methyl methacrylate initiated by the redox system Mn(III)–glycerol was studied in aqueous sulfuric acid in the temperature range of 30–40°C, and the rates of polymerization, R_p, and Mn³⁺ disappearance, etc., were measured. The effect of certain water-miscible organic solvents and certain cationic and anionic surfactants on the rates of polymerization has been investigated. A mechanism involving the formation of a complex between Mn³⁺ and glycerol whose decomposition yields the initiating free radical with the polymerization being terminated by the metal ion has been suggested.     

Vinyl polymerization by cobaltic ions in aqueous solution. Part II. Polymerization of acrylonitrile and methyl acrylate

Polymerization of methyl acrylate in HClO₄ and HNO₃ was studied in the temperature range 10–15°C. The kinetics of the polymerization were found to be very simple, involving initiation and termination by cobaltic ions. Kinetic studies on polymerization of acrylonitrile in HClO₄ and HNO₃ revealed that water oxidation, and monomer oxidation were side reactions as in the case of methyl methacrylate. Experimental evidence favored the simultaneous initiation by Co³⁺ and CoOH²⁺ species. In H₂SO₄, certain unusual features were encountered. At low [Co³⁺], linear termination as well as termination by mutual combination occurred. Another interesting aspect was that CoSO₄⁺ initiated at low [Co³⁺]. This was unlike the case of other monomers in H₂SO₄. The rates of polymerization and rates of cobaltic ion disappearance were measured with respect to changes in [M], [Co³⁺], [H⁺], temperature, etc. The various rate constants were evaluated.     

Vinyl polymerization: Kinetics of Ce(IV)–acetophenone-initiated polymerization of acrylonitrile in acetic–sulfuric acid mixtures

The polymerization of acrylonitrile (M) initiated by the Ce(IV)–acetophenone (AP) redox pair has been studied in acetic–sulfuric acid mixtures in a nitrogen atmosphere. The rate of polymerization is proportional to [M]^3/2, [AP]^1/2 and [Ce(IV)]^1/2. The rate of disappearance of ceric ion,–R_Ce, is proportional to [AP], [M], and [Ce(IV)]. The effect of certain salts, solvent, acid and temperature on both the rates have been investigated. A suitable kinetic scheme has been proposed, and the composite rate constants k_p ²(k/k/_t) and k₀/k_i are reported.     

Block copolymerization initiated by Mn(III)-poly(ethylene glycol) redox system — general features and kinetics

The kinetics and mechanism of thermal polymerization of acrylonitrile initiated by Mn(III) pyrophosphate — poly(ethylene glycol) (PEG, molecular weight 6000) redox system in aqueous sulfuric acid medium was studied in the temperature range 30–60°C. The overall rates of polymerization and the disappearance of Mn³⁺ were determined. The polymerization was initiated by the organic free radical produced from the Mn³⁺-PEG reaction and the termination was by the metal ions. The rate of polymerization of acrylonitrile was found to be directly proportional to the square of the monomer concentration and first power of PEG concentration, and inversely proportional to the concentration of Mn³⁺. The rate of manganic ion disappearance was found to be directly proportional to manganic ion concentration and PEG concentration, and independent of the monomer concentration. Based on these observations, a plausible reaction scheme was suggested and suitable kinetic expressions were evaluated.     

Polymerization of Acrylonitrile Initiated by the Thiourea-Mn3+ Redox System

Kinetics of vinyl polymerization initiated by the redox system thiourea-Mn³⁺ were investigated in the temperature range 30–40°C in sulfuric acid, and the rates of polymerization R_p and disappearance of Mn³⁺ have been measured. The effect of certain water-miscible organic solvents and anionic surfactant on the rates of polymerization was investigated. A mechanism involving the formation of a complex between Mn³⁺ and thiourea whose decomposition yields the initiating free radical with the polymerization terminated by mutual intraction of growing radicals is suggested.     

Polymerization of Acrylonitrile: Kinetics of the Reaction Initiated by the Redox System Mn3/Mannitol

Polymerization of acrylonitrile initiated by the redox system Mn³⁺/mannitol has been investigated in aqueous sulfuric acid in the temperature range 35–50°C. The rate of polymerization R_p and the rate of disappearance of Mn⁺³ (?R_M) were measured. The effect of certain water-miscible organic solvents, inorganic salts and complexing agents on the rate of polymerization have been investigated. Based on the experimental results, a suitable reaction mechanism is suggested involving the formation of complex between Mn³⁺ and the hydroxyl group of the substrate molecule, whose decomposition yields the initiating free radical; the polymer chain is terminated by the mutual combination of growing chains.     

Polymerization of Acrylonitrile: Kinetics of the Reaction Initiated by the Mn3+-Cyclohexanol Redox System

The vinyl polymerization of acrylonitrile initiated by the redox system Mn³⁺-cyclohexanol was investigated in aqueous sulfuric acid in the temperature range of 30–45° C. The rate of polymerization R_p and the rate of Mn³⁺ ion disappearance were measured. The effects of certain water-miscible organic solvents and certain anionic, cationic, and nonionic surfactants on the rate of polymerization were investigated. Based on the results obtained, a suitable reaction mechanism involving the formation of a complex between Mn³⁺ and the alcohol, whose decomposition yields the initiating free radical with the polymer chain being terminated by the mutual combination of growing chains is suggested.     

Kinetics and mechanism of polymerization of acrylonitrile by peroxomonosulphate

The kinetics of polymerization of acrylonitrile initiated by peroxomonosulphate (PMS) has been carried out in the temperature range 45–60°C at constant ionic strength of 0.50 mol dm^?3 under deaerated conditions. The rate of polymerization R_p has been investigated at various concentrations of monomer and initiator. The effects of [monomer], [initiator], [H⁺], ionic strength, temperature, and reducing agents (organic and inorganic substrates) on the rate of polymerization have been observed. Activation energy was found to be 15.2 kcal mol^?1.     

Kinetics of polymerization initiated by Mn3+–substrate redox system. I

The kinetics and mechanism of polymerization of acrylamide (AM) initiated by manganese (III) acetate (MTA)–diglycolic acid (DGA) redox system in aqueous sulfuric acid were studied in the temperature range 20-35°C. The overall rates of polymerization and the disappearance of Mn³⁺ and the kinetic chain lengths of polyacrylamide were determined. The polymerization reaction is initiated by the organic free radical arising from the Mn³⁺–diglycolic acid reaction and the termination is by the metal ions. The rate of polymerization of acrylamide was found to be proportional to the first power of monomer and diglycolic acid and independent of manganese(III) acetate. The various rate parameters were evaluated.     

Vinyl Polymerization Initiated by Ceric Ion–Ethyl Cellosolve Redox System in Aqueous Nitric Acid

Abstract

Polymerizations of methyl methacrylate (MMA) and acrylonitrile (AN) were carried out in aqueous nitric acid at 30°C with the redox initiator system ammonium ceric nitrate-ethyl cellosolve (EC). A short induction period was observed as well as the attainment of a limiting conversion for polymerization reactions. The consumption of ceric ion was first order with respect to Ce(IV) concentration in the concentration range (0.2–0.4) × 10^?2 M, and the points at higher and lower concentrations show deviations from a linear fit. The plots of the inverse of pseudo-first-order rate constant for ceric ion consumption, (k ¹)^?1 vs [EC]^?1, gave straight lines for both the monomer systems with nonzero intercepts supporting complex formation between Ce(IV) and EC. The rate of polymerization increases regularly with [Ce(IV)] up to 0.003 M, yielding an order of 0.41, then falls to 0.0055 M and again shows a rise at 0.00645 M for MMA polymerization. For AN polymerization, R _p shows a steep rise with [Ce(IV)] up to 0.001 M, and beyond this concentration R _p shows a regular increase with [Ce(IV)], yielding an order of 0.48. In the presence of constant [NO^? ₃], MMA and AN polymerizations yield orders of 0.36 and 0.58 for [Ce(IV)] variation, respectively. The rates of polymerization increased with an increase in EC and monomer concentrations: only at a higher concentration of EC (0.5 M) was a steep fall in R _p observed for both monomer systems. The orders with respect to EC and monomer for MMA polymerization were 0.19 and 1.6, respectively. The orders with respect to EC and monomer for AN polymerization were 0.2 and 1.5, respectively. A kinetic scheme involving oxidation of EC by Ce(IV) via complex formation, whose decomposition gives rise to a primary radical, initiation, propagation, and termination of the polymeric radicals by biomolecular interaction is proposed. An oxidative termination of primary radicals by Ce(IV) is also included.     

Phase-Transfer Catalysis: Free-Radical Polymerization of Methyl Methacrylate using K2S2O8-Quaternary Ammonium Salt Catalyst System. A Kinetic Study

Abstract

The kinetics of phase-transfer-agent-assisted free-radical polymerization of methyl methacrylate using K₂S₂O₈ as the water-soluble initiator and triethylbenzylammonium chloride (TEBA) as the phase-transfer catalyst (PTC) was investigated in toluene-water biphase media at 60°C. The effect of varying [MMA], [K₂S₂O₈], [TEBA], [H⁺], the ionic strength of the medium, and the temperature on the rate of polymerization (R _p) was studied. R _p was found to be proportional to [MMA]², [K₂S₂O₈]¹, and [TEBA]^0.5. Based on the kinetic results, a mechanism involving initiation of polymerization by phase-transferred S₂O₈ ^2- and termination by Q⁺ (quaternary ammonium ion) is proposed.     

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]⁺.     

Aqueous polymerization of acrylonitrile by ascorbic acid–peroxodisulfate redox system

The polymerization of acrylonitrile initiated by an ascorbic acid–peroxodisulfate redox system was studied in an aqueous solution at 35°C in the presence of air. Molecular oxygen was found to have no effect on the polymerization reaction. An increase in ionic strength slightly increased the rate. The overall rate of polymerization, R_p, showed a square dependence on [monomer] and a half-order dependence on [peroxodisulfate]. A first-order dependence on [ascorbic acid] at low concentrations (<3.0 × 10^?3 mol L^?1) followed by a decrease in R_p at higher concentrations of ascorbic acid (>3.0 × 10^?3 mol L^?1) was also noted. R_p remained unchanged up to 40°C and showed a decline thereafter. Addition of catalytic amounts of cupric ions decreased the rate whereas ferric ions were found to increase the rate. Added sulfuric acid in the range (6.0?50.0) × 10^?5 mol L^?1 decreased the R_p.     

Polymerization of acrylonitrile initiated by ceric ion–citric acid redox system

Heterogeneous polymerization of acrylonitrile initiated by ceric ammonium sulfate–citric acid (C.A.) redox system is reported at 35 ± 0.2°C under nitrogen atmosphere. The rate of monomer disappearance is found to be proportional to [C.A.]⁰, [Ce⁴⁺]^0.63, and [Monomer]^1.59. The rate of ceric ion disappearance is directly proportional to ceric ion concentration but independent of monomer concentration. The initial rate was independent of [H₂SO₄]. The molecular weight of polyacrylonitrile increases with increasing monomer concentration and decreasing ceric ion concentration. Activation energy was found to be 27.9 kJ/mol.