Deposition of calcium carbonate films by a polymer-induced liquid-precursor (PILP) process

A polypeptide additive has been used to transform the solution crystallizat ion of calcium carbonate to a solidification process of a liquid-phase mine ral precursor. In situ observations reveal that polyaspartate induces liqui d-liquid phase separation of droplets of a mineral precursor. The droplets deposit on the substrate and coalesce to form a coating, which then solidif ies into calcitic tablets and films. Transition bars form during the amorph ous to crystalline transition, leading to sectorization of calcite tablets, and the defect textures and crystal morphologies are atypical of solution grown crystals. The formation of nonequilibrium crystal morphologies using an acidic polypeptide may have implications in the field of biomineralizati on, and the environmentally friendly aspects of this polymer-induced liquid -precursor (PILP) process may offer new techniques for aqueous-based proces sing of ceramic films, coatings, and particulates. (C) 2000 Elsevier Scienc e B.V. All rights reserved.