Adsorption of PAA on the α‐Al₂O₃ Surface

Abstract

The specific system of interest is the polyacrylic acid (PAA) and (0001) a-Al 2 O 3 surface, which was modeled and simulated by Cerius 2 4.9 software with empirical potentials. The simulation predicted that the adsorbed conformations of PAA with a molecular weight (M w ) of 5000 were train and tail at pH o4 and >10, respectively. After gradually inserting additional PAA molecular chains, the adsorption reached a saturated amount. Gel permeation chromatography experimental results showed that the adsorption amount at pH 3.6 was three times greater than that at pH 11. Based on the results from simulations and experiments, a successively increasing pH environment was modeled to illustrate the possibility of optimizing electro-steric effects by combining the higher adsorption density at a lower pH and strong steric repulsion of tail-adsorbed configuration at a higher pH.

Earthen construction: an increase of the mechanical strength by optimizing the dispersion of the binder phase

“…This results in an increase of the edge-to-edge repulsive interaction, promoting the switching of coagulated clays systems from an edge-to-face to a face-to-face configuration [45,46]. PAA polymer are adsorbed on surface oxides by means of a strong electrostatic interaction of acrylic acid groups with the positive sites surface [11,46] and, in water, the dissociation of the chains, characterized by a pKa close to 4, causes an increase of the negative net particle charge that constitutes the electrostatic effect. Then, if the adsorption ratios are higher with more acidic pH than the zero charge point, the degree of dissociation has also a large incidence on the efficiency of the dispersant.…”

Synthesis and Properties of Homogeneous Nb‐Doped Bismuth Oxide

“…Thus, the prepared mixtures without agglomeration and good homogeneity are achievable. Properties of powder surface in aqueous solutions are essential for colloidal dispersion 14–16 . The interaction between aqueous solvent, polyelectrolyte dispersants, and powder is significant and important to achieve stable suspension.…”

Freeze granulation: Powder processing for transparent alumina applications

“…6) show that the viscosity increases at pH 9 compared to pH 4, which may be due to the increased effective volume of the powder by configurational change of the PAA adsorption. 37 In addition, appearance of a yield stress can be observed at pH 9, which is proportional to the effective volume and the solid loading. 35,38 Upon dopant addition at the desired level for optimal sintering, strong interactions between dissociated PAA with the dopant cations at pH 4 39-41 caused a gel formation, which could not be characterized with the rheological setup.…”