Evaluating the mechanism of nucleation and growth of silver nanoparticles in a polymer membrane under continuous precursor supply: tuning of multiple to single nucleation pathway.

Size controlled synthesis of nanoparticles in a structured media, such as a membrane, has not yet been achieved successfully in comparison to that in solution due to the lack of mechanistic investigations on the nucleation and growth of nanoparticles in these media. Slower diffusion of precursor and monomer species inside these structured media complicates the nanoparticle formation mechanism. We herein report a novel experimental approach to reveal the mechanism of nucleation and growth during the synthesis of silver nanoparticles in a Nafion-117 membrane using radiolabeling and small angle X-ray scattering (SAXS).

Effect of Film Diffusion on the Ion-Exchange Kinetics of a Tracer Ion in Nafion-117 Membrane from a Mixture of Salt Solution.

The ion-exchange kinetics of a tracer ion (Cs and Ba) in presence of a bulk ion (Na/H) has been measured in Nafion-117 membrane for a range of concentrations of NaCl/HNO using the nonstationary radiotracer method. A systematic increase in the ion-exchange rate and decrease in the partition coefficients of the tracer ions between membrane and solution have been observed with the increase in bulk ion concentration. The sigmoidal nature of experimental profiles indicates film-diffusion-controlled kinetics even for well-stirred solutions.