Impact of molecular size of SMA-g-MPEG comb-like polymer on the dispersion of CaCO₃ suspensions

Poly(styrene-co-maleic anhydride)-g-methoxypolyethylene glycols comb-like polymer was employed as the dispersant of CaCO₃ suspensions in this paper. The comb-like polymer had much better dispersability than traditional linear polyelectrolyte. By changing the length of side chains to alter the molecular size, the dispersion of CaCO₃ suspensions was greatly influenced. The absolute value of zeta potential and the adsorption density decreased with increasing the length of side chains, while the rheological and dispersion properties had a best value when using polymers with moderate length of side chain. Calculations were performed based on the scaling law and Flory theory. It was known from the calculations that by increasing the length of side chains, the molecular size and the steric repulsion were both increased. But due to the worse activity of adsorption, the comb-like polymers with longer side chains had lower adsorption amount. The dispersability was due to the cooperation of steric repulsion and adsorption, which resulted that comb-like polymers with moderate length of side chain presented the best dispersability in actual application.