The Role of Nitroxide Degradation on the Efficiency of the Controller in Nitroxide-Mediated Radical Polymerization (NMP) of Styrene

The effect of nitroxide degradation on polymerization rate and molar mass development in the nitroxide-mediated radical polymerization (NMP) of styrene is studied using electron spin resonance (ESR) spectroscopy and a mathematical model based on the method of moments. The stability of two nitroxides...

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Veröffentlicht in:Industrial & engineering chemistry research 2020-10, Vol.59 (40), p.17786-17795
Hauptverfasser: Cuatepotzo-Dı́az, Rubén, López-Méndez, Brenda Larisa, López-Domı́nguez, Porfirio, Albores-Velasco, Martha Eugenia, Penlidis, Alexander, Vivaldo-Lima, Eduardo
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Sprache:eng
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Zusammenfassung:The effect of nitroxide degradation on polymerization rate and molar mass development in the nitroxide-mediated radical polymerization (NMP) of styrene is studied using electron spin resonance (ESR) spectroscopy and a mathematical model based on the method of moments. The stability of two nitroxides, 3,3-diphenyl-1,1-dimethyl azabutane N-oxide (azabutane) and 2,2,5-trimethyl-4-phenyl-azahexane N-oxide (TIPNO), is followed by ESR spectroscopy, and the products present in the final mixture are separated and analyzed. Significant nitroxide degradation is observed in both cases. The rate of azabutane degradation is about 100 times faster than that of TIPNO. Although a degradation mechanism is proposed, it is assumed in the model, for simplicity, that a new type of radical and a nitroso compound are produced. This new radical can propagate and terminate. Its participation is properly addressed in the polymerization scheme and its corresponding model. The model is validated using experimental data of styrene polymerization mediated by alkoxyamines derived from azabutane and TIPNO at 120 °C. Azabutane degradation significantly affects polymerization rate, initial molar mass, and end-group functionality of the polymer. The model provides a good representation of the effect of nitroxide degradation on NMP of styrene.
ISSN:0888-5885
1520-5045
DOI:10.1021/acs.iecr.0c03547