Synthesis of low-molecular weight itaconic acid polymers as nanoclay dispersants and dispersion stabilizers

Itaconic oligomers with an average molecular weight of Mn = 1500-2200 g/mol and different end-groups were prepared by 2,2 '-azobis(2-methyl-propionamidine) dihydrochloride (V-50) - induced radical polymerization of itaconic acid (IA) in aqueous solution at 65 degrees C for 24 h. Mercaptoethanol, thioglycerol, and sodium hypo -phosphite were used as chain transfer agents (CTA) with the molar ratio ranging from 30:3:1 to 30:3:4 of IA, V50, and CTA, respectively. The structure of the oligomers was confirmed by electrospray ionization mass spec-trometry (ESI-MS) and tandem mass spectrometry (ESI-MS/MS). The excellent dispersing efficiency of the oligomers at very low concentrations for Laponite (R) sols was proved by oscillatory rheology and small-angle X-ray scattering (SAXS) measurements.