Many Palladium complexes dispense Pd black or other mixed phase nanoparticles when catalyzing organic transformations, whereas some do not. Why is it so? What factors affect these nanoparticle formations?
Hi,
nanoparticles tend to aggregate together due to attractive Van der Waals forces. To keep them dispersed, you must counter that attraction with a stronger force. One option is to have electrostatic repulsion, another option is to use a capping agent, i.e., something large which attaches to the particle surface and keeps the nanoparticles far away so that the short-range VdW forces stay weak. The important factors are the affinity between the capping agent, nanoparticles, and medium, the relative size of the capping agent and particles, interparticle forces, temperature, etc. You can see our publications on nanoparticle arrangement in polymer solutions - it stems from the same fundamental principle as your case.
Article Bulk Polymer Nanocomposites with Preparation Protocol Govern...
Article Thermodynamic Parameters Controlling Nanoparticle Spatial Pa...
Article Phase diagram of bare particles in polymer nanocomposites: U...
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