Itaconic acid: From monomer properties to radical homo-polymerization in water

Abstract

Itaconic acid (ITA) is a promising renewable chemical building block. Previous research on its radical homo-polymerization in aqueous media has shown slow kinetics, low conversion, and low molecular weight polymers. In this paper, we demonstrate the impact of the intrinsic properties of itaconic acid on its polymerization conditions. Specifically, the role of the degree of ionization (α) on its structure, solubility, and reactivity towards radical polymerization in water was investigated. The results indicate that the highest solubility in water occurs when itaconic acid is half-deprotonated. At a given concentration, the reaction rate and final molecular weight decrease as the degree of ionization increases, presumably due to electrostatic effects and hydrophobic/hydrophilic variations. Despite lower reactivity, full conversion can be achieved in a relatively short time with the half-deprotonated form of itaconic acid, because the polymerization can be achieved at higher monomer concentrations. These experimental findings are further supported by computational simulations of the monomer's structure and reactivity.