2002
DOI: 10.1002/pola.10464
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Penultimate unit effects in the free‐radical copolymerization of styrene with acrylonitrile according to theoretical thermochemistry

Abstract: Penultimate unit effects in the free‐radical copolymerization of styrene with acrylonitrile were investigated by the consideration of the theoretical thermochemistry of three subsequent propagation steps in the copolymerization process at 298 K and the electronic properties of the relevant reactants. The total energies, zero‐point energies incorporating a 0.96 scale factor, and thermal enthalpy corrections for all optimized structures were computed with the B3LYP density functional theory and the 6‐311G(d,p) b… Show more

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Cited by 16 publications
(16 citation statements)
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“…However, a comparison between dependencies of the penultimate unit effects on the total spin density at the radical atom for the S-M and S-A systems did not reveal any significant difference between the two systems. Results for the S-M system reproduced the former relation 24 for the S-A system, showing that there is almost no incidence of the penultimate monomer unit on the total spin density at the radical atom ( Fig. 6).…”
Section: Free-radical Copolymerizationsupporting
confidence: 65%
See 1 more Smart Citation
“…However, a comparison between dependencies of the penultimate unit effects on the total spin density at the radical atom for the S-M and S-A systems did not reveal any significant difference between the two systems. Results for the S-M system reproduced the former relation 24 for the S-A system, showing that there is almost no incidence of the penultimate monomer unit on the total spin density at the radical atom ( Fig. 6).…”
Section: Free-radical Copolymerizationsupporting
confidence: 65%
“…However, both dependencies, that is, the enthalpy of the addition reaction versus polarity of the radical and Mulliken charges at radical atoms, are regular in contrast to the equivalent dependencies for the S-A monomer system. 24 Here again, the kinetics of the elementary propagation reaction CH 3 -A-A ⅐ ϩ A 3 CH 3 -A-A-A ⅐ seemed to play a key role in differentiation between the penultimate effects in the two systems of monomers.…”
Section: Free-radical Copolymerizationmentioning
confidence: 96%
“…Recently, we applied the B3‐LYP density functional theory (DFT)14, 15 to study the free‐radical copolymerization of the styrene–acrylonitrile monomer system. The experimental results for the composition16–18 and kinetics19–21 proved that this system could display a significant penultimate effect in a copolymerization reaction. Therefore, for the monomer system, the theoretical enthalpies of reactions for three subsequent propagation steps in the radical copolymerization at 298 K21 were evaluated.…”
Section: Introductionmentioning
confidence: 82%
“…The experimental results for the composition16–18 and kinetics19–21 proved that this system could display a significant penultimate effect in a copolymerization reaction. Therefore, for the monomer system, the theoretical enthalpies of reactions for three subsequent propagation steps in the radical copolymerization at 298 K21 were evaluated. This allowed us to estimate the theoretical enthalpic terminal (Δ H 0italicterm; implicit penultimate) and penultimate (Δ H 0italicpen; explicit penultimate) unit effects, which could be defined as the differences between the enthalpies of addition of a given monomer and those of growing radicals differing in their terminal and penultimate units, respectively.…”
Section: Introductionmentioning
confidence: 82%
“…In fact, the rapid and continuing increase in computer power has made it feasible to use ab initio QM to determine different properties, such as molecular geometries (i.e., bond lengths, bond angles, and torsional angles), energetic profiles of reactions, vibrational frequencies of molecular species, transition state structures, and reaction frequency factors, with good accuracy. Only a few pioneering works that use this technique to study free radical copolymerization reactions have been proposed in the literature 56, 62–67…”
Section: Introductionmentioning
confidence: 99%