In situ investigation of complex BaSO4 fiber generation in the presence of sodium polyacrylate.: 1.: Kinetics and solution analysis

Simple solution analysis of the formation mechanism of complex BaSO4 fiber bundles in the presence of polyacrylate sodium salt, via a bioinspired approach, is reported. Titration of the polyacrylate solution with Ba2+ revealed complex formation and the optimum ratio of Ba2+ to polyacrylate for a slow polymer-controlled mineralization process. This is a much simpler and faster method to determine the appropriate additive/ mineral concentration pairs as opposed to more common crystallization experiments in which the additive/ mineral concentration is varied. Time-dependent pH measurements were carried out to determine the concentration of solution species from which BaSO4 supersaturation throughout the fiber formation process can be calculated and the second-order kinetics of the Ba2+ concentration in solution can be identified. Conductivity measurements, pH measurements, and analytical ultracentrifugation revealed the first formed species to be Ba-polyacrylate complexes. A combination of the solution analysis results and optical microscopic images allows a detailed picture of the complex precipitation and self-organization process, a particle-mediated process involving mesoscopic transformations, to be revealed.