Effect of poly(vinyl alcohol) on the rheological and drying properties of aqueous ceria-based suspensions under various pH conditions

Poly(vinyl alcohol) (PVA), as a polymeric binder, was incorporated into ceria-based suspensions to achieve better coating-relevant properties. The pH-dependent feature of PVA on the particle surface altered the interactions between the PVA-adsorbed ceria particles, significantly affecting the rheological and drying properties of the ceria–PVA suspensions. PVA adsorption on the ceria particles was determined by the PVA conformation, which resulted from the pH-dependent degree of ionization of its non-hydrolyzed acetate groups. This adsorption modified the primary interaction between PVA-adsorbed particles in suspensions, leading to either flocculation or stabilization, as confirmed with hydrodynamic diameter and zeta potential measurements. Suspensions with well-dispersed PVA-adsorbed ceria particles exhibited shear-thinning to Newtonian behavior, with weak thixotropic characteristics, whereas suspensions with flocculated particles displayed shear-thinning and strong thixotropic features. The mobility of the PVA-adsorbed ceria particles in sessile suspension droplets during drying, analyzed using multi-speckle diffusing wave spectroscopy, critically affected the final droplet patterns after drying.