Effects of Chain Transfer Agent and Temperature on Branching and β-Scission in Radical Polymerization of 2-Ethylhexyl Acrylate

Jean-Baptiste Lena (1) , Michaël Deschamps (2, 3) , Natasha Sciortino (4) , Sarah Masters (1) , Marie Squire (1) , Gregory Russell (1)

1 University of Canterbury [Christchurch]
2 CEMHTI - Conditions Extrêmes et Matériaux : Haute Température et Irradiation
3 RS2E - Réseau sur le stockage électrochimique de l'énergie
4 School of Chemistry

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 13C 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 kbb values is obtained, especially for activation energy. This strongly suggests family-type behavior for acrylate kbb.

Domaines: Matériaux

Jean-Baptiste Lena, Michaël Deschamps, Natasha Sciortino, Sarah Masters, Marie Squire, et al.. Effects of Chain Transfer Agent and Temperature on Branching and β-Scission in Radical Polymerization of 2-Ethylhexyl Acrylate. Macromolecular Chemistry and Physics, 2018, 219 (9), ⟨10.1002/macp.201700579⟩. ⟨hal-01898377⟩