Unexpected irregular structures of poly(itaconic acid) prepared in Deep Eutectic Solvents

Poly(itaconic acid) (PIA) was synthesized by persulfate initiated free-radical polymerization of ternary Deep Eutectic Solvents (DES) containing equimolar amounts of itaconic acid (IA) as hydrogen-bond donor, quaternary ammonium salt, namely choline chloride (CC) or tetraethylammonium chloride (TEAL) as hydrogen-bonds acceptors, and water as the initiator solvent. The syntheses were carried out at 65 degrees C for 2 h, and polymers produced were purified by dialysis and by treatment on strong cation exchange resin. The microstructures of the polymers were analysed using H-1, C-13 and H-1-C-13 HSQC NMR spectroscopy. The unexpected methylene and methine groups resulting from decarboxylation and/or branching as well as choline ester moieties were detected as irregular structures in PIA synthesised in IA-TEAC and IA-CC DES, respectively.