Biomimetic synthesis of calcium carbonate films on bioinspired polydopamine matrices

Abstract

We combine the active surface of polydopamine (PDA) with the biomimetic mineralization of CaCO3 to obtain the macroscopically continuous CaCO3 films under mild conditions. In this approach, the organic matrices were adhesive PDA coatings, which were dip-coated on silicon wafers by the self-polymerization of dopamine in an alkaline aqueous solution (pH 8.5). The inorganic layers were CaCO3 films, which were formed in a CaCl2 solution in the presence of poly(acrylic acid) (PAA) via a CO2 diffusion method. During the biomimetic mineralization, amorphous calcium carbonate (ACC) was formed on PDA matrices with the help of PAA, which, subsequently, was transformed into a flat continuous calcite film on the PDA matrices. As the mineralization time increased, a new layer of CaCO3 crystals was formed over the calcite and, as a result, led to continuous CaCO3 films with rough surfaces. The thicknesses of CaCO3 films can be controlled by tuning the mineralization time. Our approach may provide a simple, yet efficient way for the preparation of macroscopically continuous organic–inorganic composite CaCO3 films under mild conditions. Moreover, superhydrophobic surfaces can be successfully achieved via a hydrophobic modification of the rough CaCO3 films, which make them suitable candidates for a variety of superhydrophobic applications, such as self-cleaning surfaces or anticorrosion, antiadhesive coatings.