Synthesis of linear and crosslinked isosorbide-containing poly(β-thioether ester) via amine-catalyzed thiol-Michael addition

In this work, the amine-catalyzed thiol-Michael reaction of isosorbide or isomannide-derived dithiols as Michael-donors, with some diacrylates and dimethacrylates as Michael-acceptors, is reported. In a first part, different amines (1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU), dimethylaminopyridine (DMAP), Amberlyst® A-21 and hexylamine (HA)) were tested as catalysts for reactions involving diacrylates and dimethacrylates in acetonitrile, respectively. Molecular weight taken as the relevant criterion, DBU and DMAP were found to be equally efficient for polymerization with acrylates while DBU was the most efficient one with methacrylates. A library of polymers differing from the structure of the used diacrylate (some of them derived from isosorbide or isomannide) or dimethacrylate was prepared, with fair molecular weights and Tg varying from –22 to +32 °C. Then oligomers with controlled molecular weight and good end group fidelity were prepared, and were further used in a two-stage crosslinking reaction to prepare soft and elastic biobased crosslinked polymers via thiol-Michael addition.