During nanoparticles synthesis, reducing agents are used to reduce the metal to zero oxidation state, is it necessary to change nanoparticles to aero oxidation state, and when the formation of particles, and when and how capping agent play its role.
Capping agents form bonding themselves and act as a cage.It prevents the interaction of nano particles with one another. Nano particles when interact they agglomerate and lose their size and shape.
Dear Poorani mam,
Kindly let me know wht kind of Capping agents has to be used for chalcogenide nanoparticle sytnheiss?
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Dennish
In practice main role is to make them compatible with the continuous phase. In addition the could also limit the size, i.e. stop the growth process and shield against other chemical reactions.
Particles in tiny scale (nano size) has tendency to agglomerate due to Vander-wall's attraction between them and particles may become transferred to bigger particles than nanoparticles i.e. micro particles. This is the reason for the instability of the nanoparticles. However, nanoparticles can be stabilized with a capping agent. The most common capping agents are polyethylene glycol (PEG), ethylenediaminetetraacetic acid (EDTA), polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA), Chitosan, Polysaccharides etc.
Krishna Kanta Samanta - opposite to widespread believe van der Waals forces are proportional to particle mass, i.e., smaller for small particles. This is the basis for size selective flocculation and separation of oversized particles. Main mechanism of particle growth is Ostwald ripening.
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