Computational Study of Cyclohexanone–Monomer Co-initiation Mechanism in Thermal Homo-polymerization of Methyl Acrylate and Methyl Methacrylate

Liu, Shi; Srinivasan, Sriraj; Grady, Michael C.; Soroush, Masoud; Rappe, Andrew M.

doi:10.1021/jp2124394

Cited by 22 publications

(16 citation statements)

References 45 publications

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“…The LbL fabrication process is identical to our previous publications, where negatively charged gold nanoparticles (3 nm diameter, 20 ppm, Purest Colloids) are deposited LbL with positively charged inert long‐chain polyelectrolyte (10 × 10 −3 m poly(allylamine hydrochloride) (PAH) (Sigma–Aldrich). The highly conductive and porous CNC layers within the actuator provided extra volume for ion accumulation and thus enhance the bending performance of the actuator.…”

Section: Methodsmentioning

confidence: 99%

Well‐Defined Imidazolium ABA Triblock Copolymers as Ionic‐Liquid‐Containing Electroactive Membranes

Jangu

Wang

et al. 2014

Macro Chemistry & Physics

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Nitroxide-mediated polymerization (NMP) affords the synthesis of well-defi ned ABA triblock copolymers with polystyrene external blocks and a charged poly(1-methyl-3-(4-vinylbenzyl)-imidazolium bis(trifl uoromethane sulfonyl)imide central block. Aqueous size-exclusion chromatography (SEC) and 1 H NMR spectroscopy studies confi rm the control of the composition and block lengths for both the central and external blocks. Dynamic mechanical analysis (DMA) reveals a room temperature modulus suitable for fabricating these triblock copolymers into electroactive devices in the presence of an added ionic liquid. Dielectric relaxation spectroscopy (DRS) elucidates the ion-transport properties of the ABA triblock copolymers with varied compositions. The ionic conductivity in these single-ion conductors exhibits Vogel-FulcherTammann (VFT) and Arrhenius temperature dependences, and electrode polarization (EP) analysis determines the number density of simultaneously conducting ions and their mobility. The actuators derived from these triblock copolymer membranes experience similar actuation speeds at an applied voltage of 4 V DC, as compared with benchmark Nafi on membranes. These tailorable ABA block copolymers are promising candidates for ionic-polymer device applications.

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Section: Methodsmentioning

confidence: 99%

Well‐Defined Imidazolium ABA Triblock Copolymers as Ionic‐Liquid‐Containing Electroactive Membranes

Jangu

Wang

et al. 2014

Macro Chemistry & Physics

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“…The Wigner tunneling correction method is used for β‐scission reactions. Detailed formulas for Eckart and Wigner corrections can be found in our previous work and Supporting Information. The rate constant at a temperature T, k ( T ), is then calculated using

k (T) = κ {(c °)}^{1 - m} \frac{k_{normalB} T}{h} \exp \frac{Δ S^{\neq}}{R} \exp \frac{- Δ H^{\neq}}{R T}

in which κ is the tunneling correction, c ° is the inverse of the reference volume assumed in the calculation of translational partition function, m is the molecularity of the reaction, h is Planck constant, k B is the Boltzmann constant, R is the ideal gas constant, Δ S ≠ is the entropy of activation, and Δ H ≠ is the enthalpy of activation.…”

Section: Methodsmentioning

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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“…Furthermore, both the two symmetric breaks of the carbon-carbon bonds that can occur when a MCR undergoes a β-scission reaction were studied [70,106,143,144,151,152]. Finally, reactions relevant in high temperature processes like thermal self-initiation were approached by quantum chemical investigations [151,153,154].…”

Section: Secondary Reactionsmentioning

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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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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Computational Study of Cyclohexanone–Monomer Co-initiation Mechanism in Thermal Homo-polymerization of Methyl Acrylate and Methyl Methacrylate

Cited by 22 publications

References 45 publications

Well‐Defined Imidazolium ABA Triblock Copolymers as Ionic‐Liquid‐Containing Electroactive Membranes

Well‐Defined Imidazolium ABA Triblock Copolymers as Ionic‐Liquid‐Containing Electroactive Membranes

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

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

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