Adsorption and adhesion of poly(vinyl alcohol) and poly(ammonium acrylate) as organic additives for wet mold processing of Al2O3

Adsorption and adhesion of polyvinyl alcohol (PVA) molecules on Al2O3 surfaces in pH 3–10 or 0–0.1 mass% poly(ammonium acrylate) (PAA) aqueous solution was examined using the AFM colloidal probe method. The PVA behavior on the solid surface was estimated using force curve measurements obtained using colloidal probe AFM. Extensions originating from the bridging of PVA between the solid surfaces were observed primarily at less than approximately 200 nm in the pH 3 aqueous solution. The extensions, which were observed at more than approximately 600 nm for pH 6 and 10 aqueous solutions, resulted from different conformations of the PVA molecules. In the PVA–PAA system, the number of extensions decreased by increasing the PAA content. This was not observed in a PAA aqueous solution of greater than 0.1 mass%, which indicates that PAA was adsorbed selectively onto the solid surface. The force curve showed that PAA was more effective than PVA.