Polymerization of renewable itaconic acid in deep eutectic monomers: Effect of the quaternary ammonium cation structure

A systematic investigation has been carried out on the synthesis of poly(itaconic acid) (PIA) in Deep Eutectic Monomer (DEM) systems, composed of bio-derived itaconic acid (IA) and quaternary ammonium chlorides (QCl) varying in their cation structure. The physicochemical properties including density, viscosity, Kamlet-Taft parameters and polarity as Nile Red transition energy of DEMs supported with spectroscopic studies (FT-IR, 1H and 13C NMR) are reported. It was observed that cation structure of the ammonium chloride impacts on the physicochemical properties and radical polymerization of DEMs. More notably, the correlations between the KamletTaft hydrogen bonding accepting ability (beta) of the DEMs and both IA polymerization rate and the molecular weight of the synthesized PIA were found. These findings provided theoretical guidance on designing DEMs tailored to specific polymerization process.