Photoinduced Acrylate Polymerization: Unexpected Reduction in Chain Branching. Issue 16 (1st June 2015)

• Record Type: Journal Article
• Authors: Wenn, Benjamin; Reekmans, Gunter; Adriaensens, Peter; Junkers, Thomas
• Is Part Of: Macromolecular rapid communications. Volume 36:Issue 16(2015:Aug.)
• Page Start: 1479
• Page End: 1485
• Publication Date: 2015-06-01
• Subjects: Macromolecules -- Periodicals; Polymers -- Periodicals; Chemistry -- Periodicals; 547.705
• DOI: 10.1002/marc.201500198
• Languages: English
• ISSNs: 1022-1336

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>The branching stemming from midchain radical formation in <italic>n</italic>‐butyl acrylate polymerization is investigated via melt‐state ¹³C NMR measurements. The dependence of the degree of branching (DB) on the monomer conversion of the system is examined for photoinduced polymerizations, revealing a steady increase in branching with conversion. For polymerization at moderate light intensities, an increase in branching from 0.03% to 0.37% is observed for polymerizations at 60 °C, which is fivefold below the level of branching observed in thermally initiated poly­merizations under otherwise identical reaction conditions. The reason for this overall reduction in branching remains momentarily unclear; yet, a strong dependence of branching on light intensity is observed. While polymerization under a 1 W LED lamp results at almost full monomer conversion in branching degrees of 0.22%, polymerization under a 400 W lamp yields 1.81% of chain branches. <graphic position="anchor" mimetype="image" xlink:href="ark:/27927/pgj2f9rjg86" orientation="portrait" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></p> </abstract>