Spontaneous polymerization of methyl methacrylate. 8. Polymerization kinetics of acrylates containing chlorine atoms

Lingnau, J.; Meyerhoff, G.

doi:10.1021/ma00134a068

Cited by 21 publications

(14 citation statements)

References 4 publications

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“…The electron-withdrawing effect of the cyano group is not significant enough to allow for the abstraction of adjacent protons. 31 1H,1H,2H,2H-Perfluorooctyl methacrylate can form reactive radical species, either spontaneously at high temperatures 32,33 or by reaction with an initiator derived free radical, which then combines with the radical center in the polymer backbone resulting in the formation of a graft (Scheme 1b).…”

Section: Resultsmentioning

confidence: 99%

Molecular Simulations and Experimental Characterization of Fluorinated Nitrile Butadiene Elastomers with Low H₂S Permeability

Luo

Putnam

Incavo

et al. 2019

Ind. Eng. Chem. Res.

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The elastomer seals that are used in the processing of sour gas in the oil and gas industry must be able to withstand chemical degradation by corrosive materials such as hydrogen sulfide present in the sour gas. Nitrile rubbers, including hydrogenated nitrile butadiene (HNBR), are commonly used because they have low glass transition temperatures, good low-temperature sealing ability, and excellent resistance to swelling by hydrocarbons. They are, however, prone to chemical modifications, including chain scission, cross-linking, and sulfur incorporation, that result in changes in mechanical properties after contact with H2S. Fluoroelastomers are promising alternatives but have higher glass transition temperatures than nitrile rubbers, which affect their low-temperature performance. The approach of free-radical grafting of a semifluorinated alkyl methacrylate, 1H,1H,2H,2H-perfluorooctyl methacrylate (F6H2MA), to HNBR, to improve its resistance to H2S was investigated. The effects of grafting density of F6H2MA on the solubilities and diffusion coefficients of H2S, and carbon dioxide, which is also present in sour gas, were studied using molecular dynamics and Monte Carlo simulations. The influence of acrylonitrile concentration in the copolymer was characterized. Simulated dilatometry and differential scanning calorimetry measurements showed that the grafting of F6H2MA to HNBR did not result in a significant increase in the glass transition temperature of the copolymer. H2S permeability through the fluorinated HNBR showed a significant decrease with an increase in F6H2MA concentration. The results of molecular simulations were corroborated by measurement of mechanical properties of elastomer samples aged in a sour-gas environment at 250 °F and 1000 psig for 24 h. Gravimetric and volumetric swelling, as well as mechanical properties of the aged samples, was measured for comparison with the original unaged samples. The degrees of swelling and mechanical property deterioration after aging were significantly suppressed by grafting HNBR with even low concentrations of the semifluorinated methacrylate.

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Section: Resultsmentioning

confidence: 99%

Molecular Simulations and Experimental Characterization of Fluorinated Nitrile Butadiene Elastomers with Low H₂S Permeability

Luo

Putnam

Incavo

et al. 2019

Ind. Eng. Chem. Res.

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“…This agrees with previous experimental observations that halogen-containing acrylate monomers polymerize at a much higher rate. 61…”

Section: Theory and Computational Methodsmentioning

confidence: 99%

Modeling Spin-Forbidden Monomer Self-Initiation Reactions in Spontaneous Free-Radical Polymerization of Acrylates and Methacrylates

et al. 2014

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A spin-forbidden reaction is a reaction in which the total electronic spin-state changes. The standard transition-state theory that assumes a reaction occurs on a single potential energy surface with spin-conservation cannot be applied to a spin-forbidden reaction directly. In this work, we derive the crossing coefficient based on the Wentzel-Kramers-Brillouin (WKB) theory to quantify the effect of intersystem crossing on the kinetics of spin-forbidden reactions. Acrylates and methacrylates, by themselves, can generate free radicals that initiate polymerization at temperatures above 120 °C. Previous studies suggest that a triplet diradical is a key intermediate in the self-initiation. The formation of a triplet diradical from two closed-shell monomer molecules is a spin-forbidden reaction. This study provides a quantitative analysis of singlet-triplet spin crossover of diradical species in self-initiation of acrylates and methacrylates, taking into account the effect of intersystem crossing. The concept of crossing control is introduced and demonstrated computationally to be a new likely route to generate monoradicals via monomer self-initiation in high temperature polymerization.

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“…In nonstyrenic monomers, such as methyl methacrylate (MMA), Diels–Alder adducts lack the tendency to undergo hydrogen abstraction to generate monoradicals. Stickler, Meyerhoff, and coworkers18–25 studied the spontaneous thermal polymerization of MMA at high temperatures (100–130°C) and reported low‐conversion (≤ ∼ 5%), high‐average‐molecular‐weight polymers and the formation of a significant amount of dimers, trimers, and oligomers after 75 h of batch operation. The presence of diradical species and the initiation mechanism were identified from the predominant formation of a linear unsaturated dimer, dimethyl 1‐hexene 2,5 carboxylate 19–21…”

Section: Introductionmentioning

confidence: 99%

“…Theoretical considerations lead to the conclusion that sustained polymer chain growth is not possible from diradical species 23. The role of the solvent as a chain‐transfer species was studied in the spontaneous thermal polymerization of MMA23–25 and pentafluorostyrene 26. Low rates of polymerization of MMA were found in nonpolar solvents,23 and high rates of polymerization were found in halogenated solvents and polar, protic solvents, such as thiophenol.…”

Section: Introductionmentioning

confidence: 99%

“…Low rates of polymerization of MMA were found in nonpolar solvents,23 and high rates of polymerization were found in halogenated solvents and polar, protic solvents, such as thiophenol. Halogenated solvents and thiophenol were reported to increase the rate of polymerization because of the rapid chain transfer and crossing of diradical species from an unstable singlet to a stable triplet state via collisions with the heavy halogen or sulfur atom 23–25. However, the heavy atom effect in thiophenol was found to be less evident in comparison to halogenated solvents.…”

Section: Introductionmentioning

confidence: 99%

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Experimental study of the spontaneous thermal homopolymerization of methyl andn‐butyl acrylate

Srinivasan

Kalfas

Petkovska

et al. 2010

J of Applied Polymer Sci

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This article presents an experimental study of the spontaneous thermal homopolymerization of methyl acrylate (MA) and n-butyl acrylate (nBA) in the absence of any known added initiators at 120 and 140 C in a batch reactor. The effects of the solvent type, oxygen level, and reaction temperature on the monomer conversion and polymer average molecular weights were investigated. Three solvents, dimethyl sulfoxide (DMSO; polar, aprotic), cyclohexanone (polar, aprotic), and xylene (nonpolar) were used. The spontaneous thermal polymerization of MA and nBA in DMSO resulted in a lower conversion and higher average molecular weights in comparison to polymerization in cyclohexanone and xylene under the same conditions. The highest final conversion of both monomers was obtained in cyclohexanone. The high polymerization rate in cyclohexanone was most likely due to an additional initiation mechanism where cyclohexanone complexed with the monomer to generate free radicals. Bubbling air through the mixture led to a higher monomer conversion during the early stage of the polymerization and a lower polymer average molecular weight in xylene and cyclohexanone; this indicated the existence of a distinct behavior between the air-and nitrogen-purged systems. Matrixassisted laser desorption/ionization time-of-flight analysis of the polymer samples taken from nitrogen-bubbled batches did not reveal fragments from initiating impurities. On the basis of the identified families of peaks, monomer self-initiation is suggested as the principal mode of initiation in the spontaneous thermal polymerization of MA and nBA at temperatures above 100 C.

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Spontaneous polymerization of methyl methacrylate. 8. Polymerization kinetics of acrylates containing chlorine atoms

Cited by 21 publications

References 4 publications

Molecular Simulations and Experimental Characterization of Fluorinated Nitrile Butadiene Elastomers with Low H₂S Permeability

Molecular Simulations and Experimental Characterization of Fluorinated Nitrile Butadiene Elastomers with Low H₂S Permeability

Modeling Spin-Forbidden Monomer Self-Initiation Reactions in Spontaneous Free-Radical Polymerization of Acrylates and Methacrylates

Experimental study of the spontaneous thermal homopolymerization of methyl andn‐butyl acrylate

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Spontaneous polymerization of methyl methacrylate. 8. Polymerization kinetics of acrylates containing chlorine atoms

Cited by 21 publications

References 4 publications

Molecular Simulations and Experimental Characterization of Fluorinated Nitrile Butadiene Elastomers with Low H2S Permeability

Molecular Simulations and Experimental Characterization of Fluorinated Nitrile Butadiene Elastomers with Low H2S Permeability

Modeling Spin-Forbidden Monomer Self-Initiation Reactions in Spontaneous Free-Radical Polymerization of Acrylates and Methacrylates

Experimental study of the spontaneous thermal homopolymerization of methyl andn‐butyl acrylate

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Product

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Molecular Simulations and Experimental Characterization of Fluorinated Nitrile Butadiene Elastomers with Low H₂S Permeability

Molecular Simulations and Experimental Characterization of Fluorinated Nitrile Butadiene Elastomers with Low H₂S Permeability