The use of ylide (4-picolinium 4-chloro phenacyl methylide) as an initiator for the polymerization of methyl methacrylate

The thermal polymerization of methyl methacrylate [MMA] was carried out using ylide (4-picolinium 4-chloro phenacyl methylide) as an initiator. The rate of polymerization (R_p) increases with increasing monomer and initiator concentrations; The exponent value has been computed to be 1 ± 0.02 and 0.5, respectively. The reaction was carried out at four different temperatures and the overall activation energy has been computed to be 16.01 kcal/mol. The polymerization was inhibited in the presence of hydroquinone as a radical scavanger. Kinetic studies indicates that the overall polymerization takes place by a radical mechanism.     

Vinyl Polymerization. 269. Polymerization of Methyl Methacrylate Initiated by p,p'-Dimethoxydiphenyldiazomethane

Using p,p'-dimethoxydiphenyldiazomethane (DMDM) as initiator, the polymerization of methyl methacrylate (MMA) in benzene or in bulk was carried out. The initial rate of polymerization, R_p, was found to be expressed by the following equation:

R_p = k[DMDM]^0.53 [MMA]^0.84

The polymerization was confirmed to proceed by a radical mechanism. The over-all activation energy for the polymerization in benzene was calculated as 19.3 kcal/mole. The rate of thermal decomposition of DMDM was also measured in benzene and the rate equation was obtained as follows:

k_d (sec^?1) = 1.0 × 10¹⁵ exp (^?29.1 kcal/RT) (for 50-80°C)

Explanations of these observations are discussed in connection with those of the preceding papers.     

Aqueous Polymerization of Methyl Methacrylate Initiated by Pyridine-Sulfur Dioxide Complex

The aqueous polymerization of MMA was studied kinetically at 40° C using low concentrations of Py-SO₂ complex as initiator. For [Py-SO₂] < 2 × 10^?2 mol/L, R_p ∞ [PY-SO₂]^0.5 [M]^1.5, and for [Py-SO₂] > 2 × 10^?2 mol/L, R_p ∞ [Py-SO₂]^0,0[M]^1.08. Polymerization is considered to proceed by a radical mechanism. The radical generation or the initiation step is believed to proceed through equilibrium complexation between the Py-SO₂ complex and monomer molecules. For [Py-SO₂] < 2 × 10^?2 mol/L, the polymerization is characterized by bimolecular termination. Above this [Py-SO₂], chain termination by a degradative initiator transfer process assumes prominence.     

Vinyl polymerization. 361. Polymerization of 2,2,4-trimethyl-3-on-1-pentyl methacrylate

2,2,4-Trimethyl-3-on-1-pentyl methacrylate (TMPM) was first synthesized from the condensation reaction of 2,2,4-trimethyl-1-pentanol-3-on with methacrylic acid. Second, the polymerization of TMPM and the copolymerization of TMPM with styrene (St) were carried out in benzene at 60°C, using 2,2′-azobisisobutyronitrile (AIBN) as an initiator. As the result of kinetic investigation, the rate of polymerization (R_p) could be expressed by: R_p = k[AIBN]^0.5 [TMPM]^1.0. Kinetic constants of polymerization of TMPM were obtained as follows: k_p/k = 0.27 dm^3/2 mole^?1/2 sec^?1/2, 2fk_d = 1.23 × 10^?5 sec^?1, f = 0.73, C_m = 2.6 × 10^?5, C_s = 1.1 × 10^?5. From the results the reactivity of TMPM was found to be larger than that of methyl methacrylate. The overall activation energy was calculated to be 110 kJ mole^?1. The following monomer reactivity ratios and Q, e values were obtained: TMPM(M₁) ? St(M₂): r₁ = 1.50, r₂ = 0.14, Q₁ = 2.63, E₁ = 0.45.     

Kinetics of polymerization of methyl methacrylate initiated with cyclohexanone. Part I

The kinetics of radical polymerization of methyl methacrylate were investigated in a dioxane solution with cyclohexanone as initiator. It was found that the overall rate of reaction initiated with cyclohexanone (R_p) is proportional to the concentration of monomer and to the square root of the concentration of the initiator. The effect of temperature on the R_p in the temperature range of 65–95°C was discussed. The Arrhenius activation energy E_a estimated for the temperature range of 65–75°C was 137 kJ mol^?1.     

Radical copolymerization of fullerene (C60) and n‐butyl methacrylate (BMA) using triphenylbismuthonium ylide and characterization of C60–BMA copolymers

Radical copolymerization of fullerene (C₆₀) and n‐butyl methacrylate (BMA) has been carried out using triphenylbismuthonium ylide as an initiator at 70°C for 4 h in a dilatometer under nitrogen atmosphere. The kinetic expression of the polymerization is R_pα [Ylide]^0.5[C₆₀]^?1.0[BMA]^1.2, which is similar to that expected for ideal kinetics. The rate of polymerization increases with an increase in the concentration of initiator and BMA. However, it decreases with an increase in the concentration of fullerene. Fullerene acts as radical scavengers causing retardation in polymerization. The activation energy of copolymerization was estimated to be 72.2 K J mol^?1. The fullerene‐containing BMA copolymers were characterized by FTIR, ¹H NMR, ¹³C NMR, UV–vis, and GPC analyses. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 608–619, 2011     

Determination of Kinetic Parameters of Ethyl Methacrylate Polymerization Initiated by the Redox Pair SO2-tert-Butyl Hydroperoxide

Abstract

In the bulk polymerization of ethyl methacrylate with the redox initiator pair sulfur dioxide-tert-butyl hydroperoxide (SO₂-TBHP), the kinetic parameters were determined by the dead-end polymerization technique using the dilatometric method. Polymerization was conducted with various initiator pair compositions in the temperature interval of 12–35°C. An activation energy of 14.1 kJ/mol for [SO₂]/[TBHP] = 0.44 was determined for this temperature range. The values of k ² _p/k _t obtained in this study were in the interval 1.34 × 10^?4 to 1.11 × 10^?3 L/mol·s. The f/k _d ratios for the redox pair at different temperatures and for different initiator ratios were also calculated. The f/k _d ratios of the initiator pair changed between 15.1 and 187.6 seconds. The wide variations in these kinetic parameters were explained on the basis of competitive reactions between the redox pair and their reaction products.     

Kinetics and Mechanism of Polymerization of Methyl Methacrylate using Selenonium Ylide as a Novel Initiator

Polymerization of Methyl methacrylate (MMA) was carried out in dioxan at 60 ± 1°C for 90 min in dilatometer under nitrogenous atmosphere using diphenylselenonium 2,3,4,5-tetraphenylcyclopentadienylide (selenonium ylide) as a novel initiator. The exponent values for initiator and monomer were computed as 0.32 and 1.59, respectively. The overall activation energy and k_p ²/k_t were found 42.1 k J mol^?1 and 0.819 l mol^?1s^?1, respectively. The free radical mode of polymerization was confirmed by ESR spectroscopy. The FT-IR, ¹H-NMR and ¹³C-NMR spectroscopic techniques were used for its characterization.     

Copolymerization of Fullerene (C60) and Methyl Methacrylate (MMA) using Triphenylbismuthonium Ylide as a Novel Initiator and Characterization of the Copolymers (C60-MMA)

Copolymerization of fullerene (C₆₀) with methyl methacrylate (MMA) was carried out using triphenylbismuthonium ylide (abbreviated as Ylide) as a novel initiator in dioxan at 60°C for 4 h in a dilatometer under a nitrogen atmosphere. The reaction follows ideal kinetics: R_p∝ [Ylide]^0.5[C₆₀]^?1.0[MMA]^1.0. The rate of polymerization increases with an increase in concentration of initiator and MMA. However, it decreases with increasing concentration of fullerene due to the radical scavenging effect of fullerene. The overall activation energy of copolymerization was estimated to be 57 KJ mol^?1. The fullerene-MMA copolymers (C₆₀-MMA) were characterized by FTIR, UV–Vis, NMR and GPC analyses.     

Radical and cationic polymerizations of 3‐ethyl‐3‐methacryloyloxymethyloxetane

3‐Ethyl‐3‐methacryloyloxymethyloxetane (EMO) was easily polymerized by dimethyl 2,2′‐azobisisobutyrate (MAIB) as the radical initiator through the opening of the vinyl group. The initial polymerization rate (R_p) at 50 °C in benzene was given by R_p = k[MAIB]^0.55 [EMO]^1.2. The overall activation energy of the polymerization was estimated to be 87 kJ/mol. The number‐average molecular weight (M?_n) of the resulting poly(EMO)s was in the range of 1–3.3 × 10⁵. The polymerization system was found to involve electron spin resonance (ESR) observable propagating poly(EMO) radicals under practical polymerization conditions. ESR‐determined rate constants of propagation (k_p) and termination (k_t) at 60 °C are 120 and 2.41 × 10⁵ L/mol s, respectively—much lower than those of the usual methacrylate esters such as methyl methacrylate and glycidyl methacrylate. The radical copolymerization of EMO (M₁) with styrene (M₂) at 60 °C gave the following copolymerization parameters: r₁ = 0.53, r₂ = 0.43, Q₁ = 0.87, and e₁ = +0.42. EMO was also observed to be polymerized by BF₃OEt₂ as the cationic initiator through the opening of the oxetane ring. The M?_n of the resulting polymer was in the range of 650–3100. The cationic polymerization of radically formed poly(EMO) provided a crosslinked polymer showing distinguishably different thermal behaviors from those of the radical and cationic poly(EMO)s. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1269–1279, 2001     

Polymerization of methyl acrylate with triphenylbismuthonium 1,2,3,4‐tetraphenylcyclopentadienylide as a new radical initiator

Triphenylbismuthonium 1,2,3,4‐tetraphenylcyclopentadienylide in 1,4‐dioxan initiated radical polymerization of methyl acrylate to ～30% conversion without gelation because of autoacceleration. The polymer had a viscosity‐average molecular weight of 200,000. The kinetic expression was R_pα[I]^0.3[M]^1.16, that is, the system followed nonideal kinetics because of primary radical termination and degradative chain‐transfer reactions. The values of kk_t and the energy of activation were computed as 3.12 × 10^?5 Lmol^?1s^?1 and 28 kJ/mol, respectively. The ylide dissociated to form a phenyl radical, which brought about polymerization of methyl acrylate. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2060–2065, 2004     

Studies on the kinetics of ceric–thiourea-initiated aqueous polymerization of methyl methacrylate. I. Mechanistic features in moderately acid solution

The kinetics of the aqueous polymerization of methyl methacrylate by a ceric-thiourea initiator system in moderately acid solution (pH 2.15) was studied. The rate of polymerization was proportional to 0.41 power of ceric concentration, 0.32 power of thiourea concentration, and 1.18 power of monomer concentration. The degree of polymerization was smaller than expected from the rate of polymerization. Initiation efficiency was less than one. There was no evidence of any ceric ion termination in the concentration range of 2.50 × 10^?4–2.00 × 10^?3M studied. The results are explained in terms of partial primary radical termination; the principal mode of termination, however, was bimolecular.     

Catalytic action of metallic salts in autoxidation and polymerization. IX. Polymerization of methyl methacrylate with sodium hexanitrocobaltate(III) in mixed solvent of acetone and water

Polymerization of methyl methacrylate with some cobalt (III) complexes was carried out in various solvents and in mixed solvents of acetone and water or alcohols. Sodium hexanitrocobaltate(III) was found to be an effective initiator in mixed solvent of water and acetone. The kinetic study on the polymerization of methyl methacrylate with Na₃[Co(NO₂)₆] in a water-acetone mixed solvent gave the following over-all rate equation: R_p = 8.04 × 10⁴ exp{ ?13,500/RT} [I]^1/2[M]² (mol/1.?sec). The effects of various additives on polymerization rate and the copolymerization curve with styrene suggest that polymerization proceeds via a radical mechanism. The dependence of the polymerization rate on the square of monomer concentration and the spectroscopic data were indicative of the formation of a complex between initiator and monomer.     

Polymerization of Methyl Methacrylate by Charge-Transfer Mechanism with Amines and Carbon Tetrachloride

The charge-transfer complex formed between an amine and carbon tetrachloride can initiate the polymerization of vinyl monomers in a nonaqueous solvent such as dimethylsulfoxide. Here we use cyclopentylamine (CPA) and heptylamine (HA) as the donor compounds for charge-transfer initiation of the polymerization of methl methacrylate (MMA). The rate of polymerization R_p = k[MMA]¹ [amine]^0.5 [CCl₄]^0.5 when [CCl₄] [amine] ≤ 1; when [CCl₄] [amine] < 1, R_p becomes independent of [CCl₄] and R_p = k[MMA]^1.5 [amine]^0.5. The average constant at 60°C for the polymerization of MMA in terms of monomer were (1.66 ± 0.03) × 10^?5 and (1.46 ± 0.04) × 10^?5 s^?1 with CPA and HA, respectively, when [CCl₄] [amine] ≤ 1, and (1.16 ± 0.04) × 10^?5 and (1.39 ± 0.08) × 10^?1 L/mol·s when [CCl₄]/[amine] < 1.     

Vinyl polymerization. 275. Polymerization of vinyl monomers photosensitized by tetramethyltetrazene

A study of the photopolymerization of vinyl monomers in the presence of tetramethyltetrazene (TMT) was made. TMT was found to act as an effective sensitizer. In the photopolymerization of vinyl monomers such as methyl methacrylate or styrene the rate of polymerization was expressed by the equation: R_p = k[TMT]^1/2[monomer]. The chain-transfer constant of TMT under ultraviolet irradiation was estimated to be 3.8 × 10^?2 for the above monomers. A linear correlation was found to exist between the reactivity of dimethylamino radical toward the vinyl monomers and e values for the corresponding monomers.     

Polymerization of vinyl chloride and copolymerization with carbon monoxide by a new initiator

The system comprising the ethoxydized product of triethylaluminum, cuprous chloride, and carbon tetrachloride was used as an initiator for polymerization of vinyl chloride, and the polymerization kinetics was studied. From plots of the molar number of number-average polymer chain Y/P? versus yield Y, the two parameters a ( = ∫ R_idt ? 1/2 ∫ R_tdt) and b ( = ∫ R_trdt/∫ R_pdt) were estimated to be 6 × 10^?3 mole/l. and 6.6 × 10^?4 respectively. Studies of the tacticity of the poly(vinyl chloride) showed isotactic = 49.3% and syndiotactic = 50.7%. The present initiator also permitted copolymerization of vinyl chloride with carbon monoxide; the monomer reactivity ratios were r₁ = 0.40 (vinyl chloride) and r₂ = 0.01 (carbon monoxide).     

Polymerization of acrylonitrile: Kinetics of the reaction initiated by the Fe2+/BrO3− redox system

The aqueous polymerization of acrylonitrile initiated by the bromate—ferrous redox system in aqueous sulfuric acid was studied under nitrogen atmosphere. The rate of polymerization increased with increasing concentration of ferrous in the range of 0.25-1 × 10^?2M. The percentage of conversion increased with increasing concentration of the catalyst, but beyond 2.5 × 10^?3M there was a decreasing trend in the rate of polymerization. The rate varied linearly with [monomer]. The initial rate of polymerization as well as the maximum conversion increased within the range of 1–2.5 × 10^?3M KBrO₃, but beyond 2.5 × 10^?3M the rate of polymerization decreased. The initial rate and limiting conversion increased with increasing polymerization temperature in the range 30–40°C; beyond 40°C they decreased. The effect of certain neutral salts, water-miscible solvents, complexing agents, and copper sulfate concentration on the rate of polymerization was investigated.     

A novel tridentate nitrogen donor as ligand in copper catalyzed ATRP of methyl methacrylate

A tridentate ligand, BPIEP: 2,6‐bis[1‐(2,6‐diisopropyl phenylimino) ethyl] pyridine, having central pyridine unit and two peripheral imine coordination sites was effectively employed in controlled/“living” radical polymerization of MMA at 90°C in toluene as solvent, Cu^IBr as catalyst, and ethyl‐2‐bromoisobutyrate (EBiB) as initiator resulting in well‐defined polymers with polydispersities M_w/M_n ≤ 1.23. The rate of polymerization follows first‐order kinetics, k_app = 3.4 × 10^?5 s^?1, indicating the presence of low radical concentration ([P*] ≤ 10^?8) throughout the reaction. The polymerization rate attains a maximum at a ligand‐to‐metal ratio of 2:1 in toluene at 90°C. The solvent concentration (v/v, with respect to monomer) has a significant effect on the polymerization kinetics. The polymerization is faster in polar solvents like, diphenylether, and anisole, as compared to toluene. Increasing the monomer concentration in toluene resulted in a better control of polymerization. The molecular weights (M_n,SEC) increased linearly with conversion and were found to be higher than predicted molecular (M_n,Cal). However, the polydispersity remained narrow, i.e., ≤1.23. The initiator efficiency at lower monomer concentration approaches a value of 0.7 in 110 min as compared to 0.5 in 330 min at higher monomer concentration. The aging of the copper salt complexed with BPIEP had a beneficial effect and resulted in polymers with narrow polydispersitities and higher conversion. PMMA obtained at room temperature in toluene (33%, v/v) gave PDI of 1.22 (M_n = 8500) in 48 h whereas, at 50°C the PDI is 1.18 (M_n = 10,300), which is achieved in 23 h. The plot of lnk_app versus 1/T gave an apparent activation energy of polymerization as (ΔE^≠_app) 58.29 KJ/mol and enthalpy of equilibrium (ΔH⁰_eq) to 28.8 KJ/mol. Reverse ATRP of MMA was successfully performed using AIBN in bulk as well as solution. The controlled nature of the polymerization reaction was established through kinetic studies and chain extension experiments. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4996–5008, 2005     

Acidic Peroxo Salts: A New Class of Initiators for Vinyl Polymerization. IV. Kinetics of Polymerization of Methyl Methacrylate Initiated by Potassium Monopersulfate Catalyzed by Ag(l)

Abstract

Kinetics of vinyl polymerization of methyl methacrylate (MMA) initiated by an acidic peroxo salt, such as potassium monopersulfate coupled with silver nitrate, have been investigated in aqueous medium over the temperature range from 35 to 50°C. The rates of polymerization (R_p) have been computed for various concentrations of the monomer and initiator. The effectiveness of various metal salts in catalyzing the polymerization reaction has been determined from the observed R_p values. The effects of the catalyst (AgNO₃), initiator, monomer, and various secondary aliphatic and aromatic amines on R_p and percentage conversion have been studied. The endgroups of the resultant polymers have been studied using standard methods. From the observed endgroups and kinetic results, a reaction scheme has been proposed involving initiation by ′OH or SO₄ ^? radicals, generated by the interaction of the initiator with silver nitrate and termination by mutual combination.     

Study on the Kinetics of Polymerization of Tributyltin Methacrylate

The kinetics of polymerization of tributyltin methacrylate (TBTM) has been studied in benzene solution in the temperature range 60–75°C in the presence of azobisisobutyronitrile (AIBN). We have obtained the following polymerization rate equation: R _p = K _p [TBTM]^1.5 [AIBN]^0.5. It shows that the dependence of the polymerization rate on the concentrations of the monomer TBTM and the initiator AIBN are 1.5 and 0.5 order, respectively. The activation energy of polymerization was found to be 18.1 kcal/mol. The activation energy for the degree of polymerization is approximately -12.3 kcal/mol.