Initiation Kinetics in Free‐Radical Polymerization: Prediction of Thermodynamic and Kinetic Parameters Based on ab initio Calculations

Dossi, Marco; Storti, Giuseppe; Moscatelli, Davide

doi:10.1002/mats.200900056

Cited by 35 publications

(30 citation statements)

References 46 publications

(43 reference statements)

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“…Starting from these data, frequencies of molecular species, energetic reaction profiles, vibrational transition state structures, and reaction frequency factors can be obtained explicitly and directly [62][63][64][65][66]. The rate constant of reactions involved in a FRP system can be expressed through the Arrhenius equation.…”

Section: Quantum Chemistrymentioning

confidence: 99%

“…In particular, propagation reaction of alkenes that are characterized by very simple molecular structures such as ethene [84,85], vinyl chloride [86,87], and acrylonitrile [86][87][88] were studied. Gradually, the interest was turned to the study of homopolymer systems of more complex monomers such as styrene and various acrylates [66,89] and to that of monomers with larger substituent [88,90] such as α-substituted acrylates [91].…”

Section: From Initiation To Propagationmentioning

confidence: 99%

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On the Use of Quantum Chemistry for the Determination of Propagation, Copolymerization, and Secondary Reaction Kinetics in Free Radical Polymerization

2015

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Throughout the last 25 years, computational chemistry based on quantum mechanics has been applied to the investigation of reaction kinetics in free radical polymerization (FRP) with growing interest. Nowadays, quantum chemistry (QC) can be considered a powerful and cost-effective tool for the kinetic characterization of many individual reactions in FRP, especially those that cannot yet be fully analyzed through experiments. The recent focus on copolymers and systems where secondary reactions play a major role has emphasized this feature due to the increased complexity of these kinetic schemes. QC calculations are well-suited to support and guide the experimental investigation of FRP kinetics as well as to deepen the understanding of polymerization mechanisms. This paper is intended to provide an overview of the most relevant QC results obtained so far from the investigation of FRP. A comparison between computational results and experimental data is given, whenever possible, to emphasize the performances of the two approaches in the prediction of kinetic data. This work provides a comprehensive database of reaction rate parameters of FRP to assist in the development of advanced models of polymerization and experimental studies on the topic.

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Section: Quantum Chemistrymentioning

confidence: 99%

Section: From Initiation To Propagationmentioning

confidence: 99%

On the Use of Quantum Chemistry for the Determination of Propagation, Copolymerization, and Secondary Reaction Kinetics in Free Radical Polymerization

2015

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“…Wavefunction‐based quantum chemical methods and DFT have been successfully applied to determine geometries of molecules, transition states, reaction mechanisms, and rate constants of initiation, propagation and chain transfer reactions in high temperature and controlled radical polymerization of acrylates and methacrylates . Various DFT functionals have been successfully applied to study large polymeric systems . It was shown that the 1:5 backbiting mechanism is preferred to 1:3 and 1:7 in thermal polymerization of acrylonitrile .…”

Section: Introductionmentioning

confidence: 99%

“…Various DFT functionals have been successfully applied to study large polymeric systems . It was shown that the 1:5 backbiting mechanism is preferred to 1:3 and 1:7 in thermal polymerization of acrylonitrile . Degirmenci et al studied the propagation of methyl acrylate using B3LYP, MPW1K, BB1K, MPWB1K, and MPW1B95.…”

Section: Introductionmentioning

confidence: 99%

Backbiting and β-scission reactions in free-radical polymerization of methyl acrylate

Liu

Srinivasan

Grady

et al. 2013

Int. J. Quantum Chem.

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Multiple mechanisms of backbiting and b-scission reactions in free-radical polymerization of methyl acrylate are modeled using different levels of theory, and the rigid-rotor harmonicoscillator (RRHO) and hindered-rotor (HR) approximations. We identify the most cost-effective computational method(s) for studying the reactions and assess the effects of different factors (e.g., functional type and chain length) on thermodynamic quantities, and then identify the most likely mechanisms with first-principles thermodynamic calculations and simulations of nuclear magnetic resonance (NMR) spectra. To this end, the composite method G4(MP2)-6X is used to calculate the energy barrier of a representative backbiting reaction. This calculated barrier is then compared with values obtained using density functional theory (DFT) (B3LYP, M06-2X, and PBE0) and a wavefunction-based quantum chemistry method (MP2) to establish the benchmark method. Our study reveals that the barriers predicted using B3LYP, M06-2X, and G4(MP2)-6X are comparable. The entropies calculated using the RRHO and HR approximations are also comparable. DFT calculations indicate that the 1:5 backbiting mechanism with a six-membered ring transition state and 1:7 backbiting with an eight-membered ring transition state are energetically more favored than 1:3 backbiting and 1:9 backbiting mechanisms. The thermodynamic favorability of 1:5 versus 1:7 backbiting depends on the live polymer chain length. The activation energies and rate constants of the left and right b-scission reactions are nearly equal. The calculated and experimental 13 C and 1 H NMR chemical shifts of polymer chains affected by backbiting and b-scission reactions agree with each other, which provides further evidence in favor of the proposed mechanisms.The G4(MP2)-6X calculations are performed with Gaussian 09 [61] to take advantage of the parallel algorithm of open-shell

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“…Two DFT functionals have been used to calculate the exchange and correlation energies. In addition to the B3LYP,19, 20 which has been extensively used in our previous works,7, 13, 14, 21–25 we adopted the novel hybrid meta DFT method MPWB1K developed by Zhao and Truhlar,26 based on modified Perdew and Wang exchange functional (MPW) and Becke's 1995 correlation functional (B95). As refinement of our previous calculations,14 simulations with the B3LYP functional have been performed using the 6‐311+G(d,p) basis set,27 while the 6‐31G(d,p) basis set has been used with the MPWB1K functional 28…”

Section: Computational Detailsmentioning

confidence: 99%

Quantum Chemical Investigation of Secondary Reactions in Poly(vinyl chloride) Free‐Radical Polymerization

Cuccato¹,

Dossi²,

Moscatelli³

et al. 2012

Macro Reaction Engineering

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Free-radical polymerization of vinyl chloride is investigated computationally with special attention to the secondary reactions involving mid-chain radicals (MCRs). Namely, the rate constants of backbiting, chain scission, chain transfer, and propagation reactions are evaluated using a density functional theory method. The rate coefficients of such reactions are estimated taking into account the position of the radical along the chain as well as its distance from the chain-end. In particular 1:5, 5:1, and 5:9 backbiting are the most relevant secondary reactions, followed by the slower propagation of MCRs. Finally, a kinetic model of suspension polymerization including the investigated reactions is developed, in order to determine their impact on the quality of the final polymer.

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Initiation Kinetics in Free‐Radical Polymerization: Prediction of Thermodynamic and Kinetic Parameters Based on ab initio Calculations

Cited by 35 publications

References 46 publications

On the Use of Quantum Chemistry for the Determination of Propagation, Copolymerization, and Secondary Reaction Kinetics in Free Radical Polymerization

On the Use of Quantum Chemistry for the Determination of Propagation, Copolymerization, and Secondary Reaction Kinetics in Free Radical Polymerization

Backbiting and β-scission reactions in free-radical polymerization of methyl acrylate

Quantum Chemical Investigation of Secondary Reactions in Poly(vinyl chloride) Free‐Radical Polymerization

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