The effect of stable free radicals of the kinetics and mechanism of polymerization of some vinyl monomers

Goldfein, Mark D.; Rafikov, E.A.; Kozhevnikov, V. N.; Stepukhovich, A.D.; Trubnikov, A.V.

doi:10.1016/0032-3950(75)90083-0

Cited by 14 publications

(7 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The rate constant for reaction of nitroxyl radicals with polystyryl radicals is k 2 = 1 × 10 5 L·mol -1 ·s -1 . ,14e Taking [M] = 9 mol·L -1 and the average concentration of nitroxyl radical utilized in this work, [X] = 10 -2 mol·L -1 , we obtain W 1 / W 2 ≈ 10. Therefore, during the induction period, nitroxyl radicals react with styrene propagating radicals in preference to the initiating cyanocyclohexyl radical.…”

Section: Resultsmentioning

confidence: 77%

“…Azo-initiators do not oxidize nitroxides . When AIBN was used to initiate polymerization of MMA in presence of nitroxides, the stoichiometric coefficient of inhibition, μ, was found to be greater than 1. Other authors 14 found μ = 2.8 − 6.5 for radical polymerization of partially fluorinated methacrylates in the presence of different nitroxides at 60 °C.…”

Section: Introductionmentioning

confidence: 96%

See 1 more Smart Citation

Hydrogen Transfer Reactions of Nitroxides in Free Radical Polymerizations

Gridnev

1997

Macromolecules

View full text Add to dashboard Cite

The kinetics of radical polymerization of styrene with nitroxide stable radicals and the corresponding hydroxylamines and secondary amine were investigated at 90 °C. The amine derivative was found to be inert. The hydroxylamine causes retardation of polymerization. The rate constant of termination of the styrene propagating radicals by hydroxylamines, C x, was found to be 0.18−0.43, depending on the structure of the nitroxyl. Nitroxide caused an induction period and retarded the rate after the induction period ended. Both retardations are ascribed to hydrogen transfer. In the case of hydroxylamines it is the result of hydrogen abstraction from the hydroxyl group of the hydroxylamine by the polystyryl radical. In the case of nitroxides, it is suggested that retardation is caused by hydroxylamine formed as a byproduct during the induction period when the nitroxide reacts with the propagating radical. This is generally a minor side reaction of the propagating radical scavenging by nitroxyl radicals, but this reaction may become important at elevated temperatures when the adduct of the styrene radical with nitroxide is unstable and a reversible reaction prevails. When these two reactions of retardation occur simultaneously, it makes termination of the propagating radicals by nitroxides a catalytic reaction.

show abstract

Section: Resultsmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 96%

Hydrogen Transfer Reactions of Nitroxides in Free Radical Polymerizations

Gridnev

1997

Macromolecules

View full text Add to dashboard Cite

show abstract

“…The configuration of the playing field in this work is based on the chain-reaction concept laying the foundation of the complex polymerization process that thus presenting it as a well-traced sequence of superpositional elementary reactions [26,27]. From a theoretical viewpoint, such a vision of polymerization is the most favorable for using the quantum-chemical (QC) techniques for its virtual consideration, reducing it to the consideration of individual elementary reactions [28,29]. The theory of elementary reactions and their QC consideration has been going on for many decades [30][31][32][33][34], and the only complaint about the certain limitations of these studies can be the fact that highly welcome QC calculations of sets of one-type reactions did not become widespread.…”

Section: Playing Field and Characters Of The Digital Twins' Virtual F...mentioning

confidence: 99%

Virtual Free-Radical Polymerization of Vinyl Monomers in View of Digital Twins

Sheka

2023

Polymers

View full text Add to dashboard Cite

The first case of virtual polymerization based on the concept of digital twins (DTs) is presented. The free-radical polymerization of vinyl monomers is considered to be a chain reaction consisting of a set of elementary ones. Those three types, related to the polymerization initiation and propagation as well as to the termination of polymer chain growth, are discussed. Special sets of DTs, whose total number approaches 60, distinguish each reaction type. The calculations are carried out using a semi-empirical version of the unrestricted Hartree–Fock approximation. The main energy and spin-density parameters of the ground state of the DTs are determined. The barrier profiles of two pairs of DTs are calculated, based on which two Evans–Polanyi–Semenov relations, attributed to elementary reactions of type (1) and (2), are constructed. These provide a quite reliable evaluation of the activation energy for the initiation and propagation of the free-radical polymerization of vinyl monomers in all the cases. The decisive role of spins in the formation of the elementary reaction transition states is established.

show abstract

“…A detailed consideration of reactions (1) and (2) has been performed recently [3,4]. Reactions (3)(4)(5)(6)(7)(8)(9)(10)(11)(12) are the main goal of the current study.…”

Section: Potential Frcp Of Vinyls With Stable Radicals In Light Of Su...mentioning

confidence: 99%

“…Chain reaction, as a set of independent elementary reactions (ERs), has proven to be in high demand in modern virtual polymerics based on the concept of digital twins (DTs) [3,4]. The latter implements the long-desired consideration of reactions of the same type, carried out under the same conditions, which makes it possible to determine with high conviction the main trends accompanying a complex and multifaceted polymerization process [5][6][7]. Recently published first results [3,4] are related to the virtualization of free-radical polymerization (FRP) of vinyl monomers and the role in this process of small additives of stable radicals such as TEMPO and C60 fullerene.…”

Section: Introductionmentioning

confidence: 99%

Virtual Vibrational Spectrometry of Stable Radicals—Necklaced Graphene Molecules

Sheka

2022

Nanomaterials

View full text Add to dashboard Cite

The article presents results of an extended virtual experiment on graphene molecules performed using the virtual vibrational spectrometer HF Spectrodyn that exploits semiempirical Hartree-Fock approximation. The molecules are composed of flat graphene domains surrounded with heteroatom necklaces. Not existing individually, these molecules are met in practice as basic structure units of complex multilevel structure of all sp2 amorphous carbons. This circumstance deprives the solids’ in vitro spectroscopy of revealing the individual character of basic structural elements, and in silico spectrometry fills this shortcoming. The obtained virtual vibrational spectra allow for drawing first conclusions about the specific features of the vibrational dynamics of the necklaced graphene molecules, caused by spatial structure and packing of their graphene domains as well as by chemical composition of the relevant necklaces. As shown, IR absorption spectra of the molecules are strongly necklace dependent, once becoming a distinct spectral signature of the amorphous body origin. Otherwise, Raman spectra are a spectral mark of the graphene domain’s size and packing, thus disclosing the mystery of their universal D-G-band standard related to graphene-containing materials of various origins.

show abstract

The effect of stable free radicals of the kinetics and mechanism of polymerization of some vinyl monomers

Cited by 14 publications

References 4 publications

Hydrogen Transfer Reactions of Nitroxides in Free Radical Polymerizations

Hydrogen Transfer Reactions of Nitroxides in Free Radical Polymerizations

Virtual Free-Radical Polymerization of Vinyl Monomers in View of Digital Twins

Virtual Vibrational Spectrometry of Stable Radicals—Necklaced Graphene Molecules

Contact Info

Product

Resources

About