Effects of Chain Transfer Agent and Temperature on Branching and β‐Scission in Radical Polymerization of 2‐Ethylhexyl Acrylate. Issue 9 (23rd March 2018)

• Record Type: Journal Article
• Authors: Lena, Jean‐Baptiste; Deschamps, Michaël; Sciortino, Natasha F.; Masters, Sarah L.; Squire, Marie A.; Russell, Gregory T.
• Is Part Of: Macromolecular chemistry and physics. Volume 219:Issue 9(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-03-23
• Subjects: β‐scission -- branching -- electrospray ionization (ESI)‐mass spectrometry -- NMR -- poly(2‐ethylhexyl acrylate); Polymers -- Periodicals; Polymerization -- Periodicals; Synthetic products -- Periodicals; Macromolecules -- Periodicals; 547.7
• DOI: 10.1002/macp.201700579
• Languages: English
• ISSNs: 1022-1352

Abstract

Abstract: Poly(2‐ethylhexyl acrylate) is synthesized by conventional radical bulk polymerization both with and without 1‐dodecane thiol as chain transfer agent (CTA) at temperatures from 4 to 140 °C. Electrospray‐ionization mass spectrometry is used to analyze the polymer. This reveals the occurrence of significant β‐scission at high temperature and confirms the presence of CTA‐capped polymers at all temperatures, as well as combination products from 4 to 65 °C. Subsequent 13 C melt‐state NMR analysis allows quantification of branching and β‐scission. Both are reduced when CTA is present, consistent with a "patching" effect. As expected, the amounts of β‐scission and branching increase with synthesis temperature, although β‐scission dominates at the highest temperature. The backbiting rate coefficient of 2‐ethylhexyl acrylate is determined from NMR results, taking β‐scission into account for the first time. Remarkable agreement with literature k bb values is obtained, especially for activation energy. This strongly suggests family‐type behavior for acrylate k bb . Abstract : Poly(2‐ethylhexyl acrylate) is synthesized from 4 to 140 °C and characterized by electrospray‐ionization mass spectrometry and 13 C melt‐state NMR spectroscopy. The percentages of branching points and unsaturated terminal double bonds are determined, and thus the backbiting rate coefficient is estimated.