The role of hyperbranched polyesters in acrylamide‐based polymers as thickening agents in aqueous solutions

Abstract

Acrylamide polymers are typically used in industrial and healthcare sectors as thickening agents; however, their thickening capabilities rely mainly in their molecular mass. A versatile and simple strategy to improve their performance is the copolymerization with specific monomers or their chemical modification with structures like dendritic or hyperbranched molecules. This study introduces a novel acrylamide-acrylic acid polymer grafted with minor proportions (≤4.0 wt%) of Boltorn H30, a hyperbranched polyester monomer. The incorporation of Boltorn H30 aims to exploit the hyperbranched architecture´s impact on the viscosity and rheological behavior of polymer solutions. Polymers with 0.4 and 4.0 polyester wt% characterized by several analytical techniques displayed improved viscosity in aqueous solution compared against the parent poly(acrylamide-co-acrylic acid). Results revealed that while the molecular mass distribution changed between 20% and 94%, the thickening capabilities significantly improved with increments of 2.7 and 3.8 times compared to that of the original polymers. These findings demonstrate that even with a minimal incorporation of hyperbranched polyesters, the abundance of hydroxyl groups fosters extensive hydrogen bonding, resulting in enhanced viscosity properties of the polymer.