Morphological evaluation and film formation with iso-oriented calcite crystals using binary poly(acrylic acid)

The influence of poly(acrylic acid) (PAA) on the morphological evolution of calcite crystals depended on the concentration and molecular weight of the polyelectrolyte in an aqueous solution. A low-molecular-weight PAA (Mw 2000) weakly suppressed the regular crystal growth and miniaturized calcite grains as a suppressant. High-molecular-weight PAA (Mw 90 000 or 250 000) drastically decreased the grain size as a strong suppressant and promoted the formation of thin films as a template on the surface of a glass substrate. The difference in the performance of the PAAs was ascribed to the mobility and conformation derived from the polymer chain length. In a binary polymer system (Mw 2000 and 250 000), lozenge-shaped films consisting of iso-oriented nanoscale crystal grains were produced through nucleation with the high-molecular-weight PAA anchored to a glass substrate and controlled growth with the mixture of low- and high-molecular-weight PAAs.