A New Approach to Thickening Polymers through the Esterification Reaction of Poly(styrene-<i>alt</i>-maleic anhydride) and Sugar (Alcohol)

The synthesis and application of thickening polymers for aqueous solutions are crucial in a multitude of industries. Herein, we propose the 4-dimethylaminopyridine (DMAP)-catalyzed esterification reaction between poly(styrene-alt-maleic anhydride) (SMA) and sugar (alcohol) for preparing a new type of thickening polymer. A thorough investigation of the esterification kinetics of SMA and sorbitol as well as the average reacted hydroxyl number (Ne) of sorbitol was conducted by a combination of Fourier transform infrared spectroscopy (FT-IR) and potentiometric titration. The present method can be extended to sugars, including sucrose and maltose, thus delivering SMA-g-sugar (alcohol) with diverse structures. The apparent viscosity of aqueous solutions thickened by SMA-g-sugar (alcohol) before and after further chain extension with diamine was evaluated by using a rotational rheometer. After chain extension with polyetheramine D230, great thickening property and excellent stability against thermal cycles and shear time can be achieved. The present method has broad compatibility, controllable polymer structure, and possibility for further chain extension, thus holding great prospect for preparing thickening polymers applied across different industrial sectors.