SMA-g-MPEG comb-like polymer as a dispersant for Al2O3 suspensions

Abstract

SMA-g-MPEG comb-like polymer is first employed as the dispersant of Al2O3 suspensions in this paper. The comb-like polymer has anionic polycarboxylate backbone, which makes the polymer easily absorbed on the cationic surface of Al2O3 particles; on the other hand, the comb-like polymer has hydrophilic MPEG side chains, which extend into the solution to provide steric repulsion after the comb-like polymer is absorbed on the surface of Al2O3 particles. The adsorption behavior, zeta potential, apparent viscosity, granularity and TEM images of the Al2O3 suspensions using SMA-g-MPEG as dispersant are investigated. The addition of SMA-g-MPEG improves the dispersibility and decreases the apparent viscosity of the Al2O3 suspension observably. The impacts of the length of side chains on the dispersion of Al2O3 suspensions are particularly discussed. The adsorbed molecular number of the dispersant decreased by increasing the length of side chains. The zeta potential of Al2O3 suspension is more negative by using comb-like polymer with shorter side chains. Based on the steric repulsion and adsorbed molecular number, SMA-g-MPEG with moderate length of side chain is found to have the best dispersibility for Al2O3 suspension.