Termination Mechanism of the Radical Polymerization of Acrylates

Nakamura, Yasuyuki; Lee, Richmond; Coote, Michelle L.; Yamago, Shigeru

doi:10.1002/marc.201500677

Cited by 42 publications

(72 citation statements)

References 26 publications

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“…We simulated the reactions carried out by Nakamura et al assuming a model (details in the Supporting Information) in which the macroinitiator undergoes decomposition and then either backbiting or termination with other radicals present in the system. It should be noted that the assumption of first order decomposition is a simplification of the experimental system that provides an estimate of the radical concentration throughout the experiment.…”

Section: Resultsmentioning

confidence: 99%

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On the Termination Mechanism in the Radical Polymerization of Acrylates

Ballard

Hamzehlou

Ruipérez

et al. 2016

Macromol. Rapid Commun.

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In a recent publication, Nakamura and co-workers studied the termination mechanism in the radical polymerization of acrylates. Contrary to conventional thinking, their conclusion is that termination is overwhelmingly by disproportionation. This finding impacts on a large body of the previous work in the polymerization of acrylic monomers which this work seeks to address. Analysis of the molecular weight distribution of acrylic polymers obtained under different polymerization conditions shows that termination by combination is the more probable mechanism for mutual termination of secondary radicals. It is proposed that in the experiments conducted by Nakamura and co-workers, backbiting plays a key role and their experimental data are reinterpreted, showing that they are more revealing with respect to the mode of termination of the midchain radical produced by backbiting, than to bimolecular termination of secondary radicals.

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Section: Resultsmentioning

confidence: 99%

“…Nakamura et al have recently described a new technique to determine the mode of termination using a monodisperse, dormant organotellurium terminated polymer which is activated by UV light . By comparison of the molecular weight distribution (MWD) of the polymer before and after irradiation they determined the mode of termination.…”

Section: Introductionmentioning

confidence: 99%

On the Termination Mechanism in the Radical Polymerization of Acrylates

Ballard

Hamzehlou

Ruipérez

et al. 2016

Macromol. Rapid Commun.

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“…In this case the % of chains terminated by radical means are below 1%, what indicating that seATRP was conducted with preserved chain end functionality, therefore the bimodality cannot be detected by GPC, even if termination will be 100% of coupling. Probability of the intramolecular termination of acrylates can be enhanced due to a close proximity of radicals but also can be diminished due to radical segregation [15,64] (Figure 9 and 10).…”

Section: Synthesis Of 21-arm Star Block Copolymersmentioning

confidence: 99%

Synthesis of cationic star polymers by simplified electrochemically mediated ATRP

Chmielarz¹

2016

Express Polym. Lett.

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Abstract. Cyclodextrin-based cationic star polymers were synthesized using β-cyclodextrin (β-CD) core, and 2-(dimethylamino)ethyl methacrylate (DMAEMA) as hydrophilic arms. Star-shaped polymers were prepared via a simplified electrochemically mediated ATRP (seATRP) under potentiostatic and galvanostatic conditions. The polymerization results showed molecular weight (MW) evolution close to theoretical values, and maintained narrow molecular weight distribution (MWD) of obtained stars. The rate of the polymerizations was controlled by applying more positive potential values thereby suppressing star-star coupling reactions. Successful chain extension of the ω-functional arms with a hydrophobic n-butyl acrylate (BA) formed star block copolymers and confirmed the living nature of the β-CD-PDMAEMA star polymers prepared by seATRP. Novelty of this work is that the β-CD-PDMAEMA-b-PBA cationic star block copolymers were synthesized for the first time via seATRP procedure, utilizing only 40 ppm of catalyst complex. The results from 1 H NMR spectral studies support the formation of cationic star (co)polymers.

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“…[15][16][17] Polymerend radicals, such as 7c,w ith controlled molecular weight are generated from the corresponding "living" polymer having the organotellurium end group 8c. [15][16][17] Polymerend radicals, such as 7c,w ith controlled molecular weight are generated from the corresponding "living" polymer having the organotellurium end group 8c.…”

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confidence: 99%

“…[15][16][17] Polymerend radicals, such as 7c,w ith controlled molecular weight are generated from the corresponding "living" polymer having the organotellurium end group 8c. [16] 2) The termination of methacrylate and styrene polymerizations are significantly changed by the viscosity of the reaction media, and selective Disp was observedi nh ighly viscous media in both cases. Please keep in mind that the structures of 9d, 10 d,a nd 11 d are identicalt ot hose of 3b, 4b,a nd 5b,r espectively.T wo significant conclusions have been drawn from the analyses of molecular weights and endgroup structures:1 )the termination of ap olyacrylate-end radical predominantly proceeds by Disp under ambient temperature, whereas major textbooks describe the termination of acrylate polymerization as Comb.…”

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confidence: 99%

The Effect of Viscosity on the Diffusion and Termination Reaction of Organic Radical Pairs

Ogihara

Abe

et al. 2019

Chemistry A European J

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The effecto fv iscosity on the diffusion efficiency (F dif )o fa no rganic radical pair in as olvent cage and the termination mechanism, that is,t he selectivity of disproportionation (Disp)a nd combination (Comb)o ft he geminated caged radical pair and the diffused radicals encountered, were investigated quantitatively by following the photolysis of dimethyl 2,2'-azobis(2-methylpropionate) (V-601) in the absence andp resence of PhSD. F dif and Disp/ Comb selectivity outside the cage [Disp (dif) /Comb (dif) ]a re highly sensitivetot he viscosity. In contrast, the Disp/Comb selectivity inside the cage [Disp (cage) /Comb (cage) ]i sr ather insensitive. The differencei nv iscosityd ependence between Disp (cage) /Comb (cage) and Disp (dif) /Comb (dif) is explained by the spin state of the radical pair inside and outside the cage and the spin state dependent configurationalc hangeso f the radical pair upon their collision. Given that the configurational change of the radicals associates the displacement and reorganization of solvents around the radicals, the terminationo utside the cage, which requires larger change than that inside the cage, is highly viscosity dependent. Furthermore,while the bulk viscosity of each solvent shows good correlation with F dif and Disp/Comb selectivity, microviscosity is the better parameterp redicting F dif and Disp (dif) /Comb (dif) selectivity regardless of the solvents.[a] X.

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Termination Mechanism of the Radical Polymerization of Acrylates

Cited by 42 publications

References 26 publications

On the Termination Mechanism in the Radical Polymerization of Acrylates

On the Termination Mechanism in the Radical Polymerization of Acrylates

Synthesis of cationic star polymers by simplified electrochemically mediated ATRP

The Effect of Viscosity on the Diffusion and Termination Reaction of Organic Radical Pairs

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