Reducing the degree of branching in polyacrylates via midchain radical patching: A quantitative melt-state NMR study

Marianne Gaborieau, Sandy P.S. Koo, Patrice Castignolles, Thomas Junkers, Christopher Barner-Kowollik

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34 Citations (Scopus)

Abstract

Degrees of branching were measured with 13C melt-state NMR in poly(n-butyl acrylates) synthesized in both the presence and absence of 1-octanethiol at various temperatures, and their precision calculated based on the signal-to-noise ratio of the quaternary carbon at the branching point. Nitrogen gas was used for all pneumatics. Samples synthesized with thiol were measured in 7 mm rotors at MAS rotational frequencies of 1.8 to 4.5 kHz, while samples synthesized without thiol were measured in 4 mm rotors at 9 kHz MAS. The relative standard deviation SD of DB was calculated from the signal-to-noise ratio of the quaternary carbon SNR. The accuracy of measured degrees of branching was ensured by full relaxation of the relevant signals between pulses. A significant decrease of branching was observed in the presence of a thiol during the polymerization process, experimentally confirming the patching effect of midchain tertiary radicals by the thiol.

Original languageEnglish
Pages (from-to)5492-5495
Number of pages4
JournalMacromolecules
Volume43
Issue number13
DOIs
Publication statusPublished - 13 Jul 2010
Externally publishedYes

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