Single-Pulse Pulsed Laser Polymerization–Electron Paramagnetic Resonance Investigations into the Termination Kinetics of n-Butyl Acrylate Macromonomers

Type of content
Journal Article
Thesis discipline
Degree name
Publisher
University of Canterbury. Chemistry
Journal Title
Journal ISSN
Volume Title
Language
Date
2012
Authors
Barth, J.
Buback, M.
Barner-Kowollik, C.
Junkers, T.
Russell, G.T.
Abstract

The termination of model mid-chain radicals (MCRs), which mimic radicals that occur in acrylate polymerization over a broad range of reaction conditions, has been studied by singlepulse pulsed-laser polymerization (SP PLP) in conjunction with electron paramagnetic resonance (EPR) spectroscopy. The model radicals were generated by initiator-fragment addition to acrylic macromonomers that were preformed prior to the kinetic experiments, thus enabling separation of termination from the propagation reaction, for these model radicals propagate sparingly, if at all, on the timescale of SP-PLP experiments. Termination rate coefficients of the MCRs were determined in the temperature range 0–60 °C in acetonitrile and butyl propionate solution as well as in bulk macromonomer over 0–100 °C. Termination rate coefficients slightly below those of the corresponding secondary radicals were deduced, demonstrating the relatively high termination activity of this species, even when undergoing MCR-MCR termination. For chain length 10, a reduction by a factor of 6 is observed. Unusually high activation energies were found for the termination rate coefficient in these systems, with 35 kJ mol⁻¹ being determined for bulk macromonomer.

Description
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Citation
Barth, J., Buback, M., Barner-Kowollik, C., Junkers, T., Russell, G.T. (2012) Single-Pulse Pulsed Laser Polymerization–Electron Paramagnetic Resonance Investigations into the Termination Kinetics of n-Butyl Acrylate Macromonomers. Journal of Polymer Science Part A: Polymer Chemistry, 50(22), pp. 4740-4748.
Keywords
ESR/EPR, kinetics (polym.), macromonomers (acrylate), mid-chain radicals, radical polymerization, termination
Ngā upoko tukutuku/Māori subject headings
ANZSRC fields of research
Field of Research::03 - Chemical Sciences::0303 - Macromolecular and Materials Chemistry::030304 - Physical Chemistry of Materials
Fields of Research::34 - Chemical sciences::3403 - Macromolecular and materials chemistry::340306 - Polymerisation mechanisms
Field of Research::03 - Chemical Sciences::0306 - Physical Chemistry (incl. Structural)::030606 - Structural Chemistry and Spectroscopy
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