Kinetic Characterization of Precipitation Reactions: Possible Link between a Phenomenological Equation and Reaction Pathway

Abstract

The characteristic time scale of reactive crystallization is traditionally investigated as a function of supersaturation in the deterministic regime, but no chemical meaning is assigned to the empirical power law. Applying chemical model systems in which various oxalate complexes form beside the precipitate, we show that the exponent provides information about the reaction pathways. The speciation of the reactant solution is revealed by combining equilibrium calculations and conductance measurements; the precipitate is identified with powder X-ray diffraction. A link between microstructure and kinetics is illustrated by scanning electron microscopy. The functionality of complex-shaped particles is examined by utilizing them as filler material to modify the wetting properties of a fluoropolymer-based thin film. Finally, it is shown that investigating the characteristic time scale as a function of the analytical concentration instead of supersaturation may also provide valuable information.