Probing the effects of polymers on the early stages of calcium carbonate formation by stoichiometric co-titration.

Potentiometric titrations are a powerful tool to study the early stages of the precipitation of minerals such as calcium carbonate and were used among others for the discovery and characterisation of key precursors like prenucleation clusters. Here we present a modified procedure for conducting such titration experiments, in which the reactants ( calcium and (bi)carbonate ions) are added simultaneously in stoichiometric amounts, while both the amount of free calcium and the optical transmission of the solution are monitored online. Complementarily, the species occurring at distinct stages of the crystallisation process were studied using cryogenic transmission electron microscopy.

In Situ Synthesis of Catalytic Active Au Nanoparticles onto Gibbsite-Polydopamine Core-Shell Nanoplates.

We report a facile method to synthesize anisotropic platelike gibbsite-polymer core-shell particles. Dopamine is self-polymerized on the surface of gibbsite nanoplates and forms a homogeneous layer on it. Transmission electron microscopy characterization of the resulting latexes demonstrates the formation of well-defined platelike core-shell particles.