EPR Study into Cross‐Termination and Fragmentation with the Phenylethyl–Phenylethyl Dithiobenzoate RAFT Model System. Issue 8 (19th February 2013)

• Record Type: Journal Article
• Authors: Meiser, Wibke; Buback, Michael; Ries, Oliver; Ducho, Christian; Sidoruk, Alana
• Is Part Of: Macromolecular chemistry and physics. Volume 214:Issue 8(2013:Apr.)
• Page Start: 924
• Page End: 933
• Publication Date: 2013-02-19
• Subjects: Polymers -- Periodicals; Polymerization -- Periodicals; Synthetic products -- Periodicals; Macromolecules -- Periodicals; 547.7
• DOI: 10.1002/macp.201200668
• Languages: English
• ISSNs: 1022-1352

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The reversible addition–fragmentation chain transfer (RAFT) equilibrium constant of the phenylethyl–1‐phenylethyl dithiobenzoate model system is deduced via EPR spectroscopy to be 31 ± 4 L mol⁻¹ at 110 °C. The difference in activation energies of addition and fragmentation, <italic>E</italic>_a(<italic>k</italic>_ad) – <italic>E</italic>_a(<italic>k</italic>_β) ≈ −45.6 kJ mol⁻¹, is close to that of the polystyryl–polystyryl dithiobenzoate system. Significant amounts of products from cross‐termination and from "missing step" reaction of the cross‐termination product with the phenylethyl radical demonstrate that intermediate radical termination, rather than slow fragmentation of the RAFT intermediate radical, is responsible for the rate retardation in the dithiobenzoate‐mediated styrene polymerization.<boxed-text content-type="graphic" position="anchor" orientation="portrait"><graphic position="anchor" mimetype="image" xlink:href="ark:/27927/pgg1xr082b3" orientation="portrait" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></boxed-text></p> </abstract>