Efficient dispersants for the dispersion of gallium zinc oxide nanopowder in aqueous suspensions

Appropriate dispersants for the dispersion of gallium zinc oxide ( GZO ) nanopowder in aqueous suspensions were identified in this study. The dispersion efficiencies and stabilization mechanisms of water‐based dispersants ammonium poly(acrylic acid) ( PAA – NH 4 ), an anionic polyelectrolyte, and polyethylenimine ( PEI ), a cationic polyelectrolyte, were compared. The experimental analyses of rheology and sedimentation showed that both PAA – NH 4 and PEI were good dispersants for the dispersion of GZO . Theoretical calculations based on Derjaguin‐Landau‐Verwey‐Overbeek theory revealed that the stabilization mechanism of PEI was mainly related to the steric effect, and a very low molecular weight of 1800 g/mol was insufficient for powder stabilization. GZO was well dispersed by PEI with high molecular weight of 10 000 g/mol, but agglomeration occurred when too much PEI was added. Compared with PEI , PAA – NH 4 was more efficient because of its high contribution to the increase in electrostatic repulsion. Based on theoretical considerations on both steric and electrostatic effects, namely, the electrosteric stabilization mechanism, PAA – NH 4 is optimal for the dispersion of GZO nanopowder in aqueous suspensions.