EPR Study of Backbiting in the Aqueous‐Solution Polymerization of Acrylamide. Issue 24 (21st October 2015)

• Record Type: Journal Article
• Authors: Kattner, Hendrik; Buback, Michael
• Is Part Of: Macromolecular rapid communications. Volume 36:Issue 24(2015:Dec.)
• Page Start: 2186
• Page End: 2191
• Publication Date: 2015-10-21
• Subjects: acrylamide -- backbiting -- EPR/ESR -- polymer kinetics -- polymers; radical polymerization; Macromolecules -- Periodicals; Polymers -- Periodicals; Chemistry -- Periodicals; 547.705
• DOI: 10.1002/marc.201500479
• Languages: English
• ISSNs: 1022-1336

Abstract

Abstract : Via electron paramagnetic resonance (EPR) spectroscopy, the type of radicals occurring during acrylamide (AAm) homopolymerization in aqueous solution is investigated between −5 and +100 °C. The radicals are produced photochemically under stationary conditions. Midchain AAm radicals (MCRs) are clearly identified by EPR which demonstrates that secondary propagating AAm radicals (SPRs) undergo backbiting reactions. Above 50 °C, the fraction of MCRs even exceeds the one of SPRs. The extent of backbiting is however well below the one in butyl acrylate polymerization at identical temperature. Abstract : Electron paramagnetic resonance spectroscopy demonstrates that both secondary propagating radicals (SPRs) and tertiary midchain radicals (MCRs) occur during acrylamide polymerization in aqueous solution. Above 50 °C, the mole fraction of MCRs exceeds the one of SPRs, but is well below the MCR content with butyl acrylate.