please tell me about role of both of them and its difference in stability of nanoparticles.
Using a strong reducing agents, or a lot of the reducing agent will produce a strong burst of nucleation. So a lot of nuclei will in-turn decrease final the particle size. so we can control the particle size by the choice and amount of the reducing agent. The capping agent could be physisorbed ions or chemisorbed functional groups and their role is to prevent the nanoparticles from coming in contact with each other and aggregating. In a popular synthesis of noble metal nanoparticles, the reducing agent and the capping agent are the same (commonly citrate ions), but this is just an example, there are other synthesis methods where they are different.
Using a strong reducing agents, or a lot of the reducing agent will produce a strong burst of nucleation. So a lot of nuclei will in-turn decrease final the particle size. so we can control the particle size by the choice and amount of the reducing agent. The capping agent could be physisorbed ions or chemisorbed functional groups and their role is to prevent the nanoparticles from coming in contact with each other and aggregating. In a popular synthesis of noble metal nanoparticles, the reducing agent and the capping agent are the same (commonly citrate ions), but this is just an example, there are other synthesis methods where they are different.
The capping agent have promising role in the stabilization of nanoparticles as it protect agglomeration of nanoparticles from combining themselves. These are also play an essential role in controlling morphology of nanostructure because of their soft - template effect, their ability to modify the chemical kinetics. Capping agents can largely influence the oriented attachment processes (growth of a nanostructure is due to two processes - Ostwald ripening and oriented attachment) as they directly modify the nanoparticle's surface.The molecular weight of the capping ligand also makes a remarkable contribution in the assembly behaviors of the nanoparticles and which is governed by the balance of forces due to van der waals interaction, capillary interaction, surface tension and hydrophobic interaction and H - bonding effect.
On the other hand, during the synthesis of nanoparticles especially metal nanoparticles, reducing agent converting metal ions to nano-metal via reduction process. Some reducing compounds are used along with stabilizer molecules to solve the purpose of reducing and capping simultaneously. In some cases (during metal nanoparticles synthesis), reducing agent with specially appointed structure can act as the capping agent too.
reducing agent is used for synthesis of nano materials while capping agent is used for stabilizing the nanoparticles.
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