Seeded-growth method

The synthesis of spherical nanoparticles using the mediated seeded-growth method has been carried out using different mild reducing agents such as citrate, organic acids or hydroxylamine and well-defined monodisperse seed particles. 

The various techniques used to study growth kinetics by the seeded growth method are now discussed. These include methods which have been used to study not only powder samples but also single crystals. 

The most successful approach to control membrane formation involves segregation of the processes of crystal nucleation and growth [24]. The so-called ex situ or secondary (seeded) growth methods, unlike the direct synthesis procedures just discussed, include a first step in which a closely packed layer of colloidal zeolite crystals, synthesized homogenously, is deposited onto... 

Bimetallic particles with layered structures have opened fascinating prospects for the design of new catalysts. Schmid et al. [10m] have applied the classical seed-growth method [20] to synthesize layered bimetallic Au/Pd and Pd/Au colloids in the size range of 20-56 nm. The sequential reduction of gold salts and palladium salts with sodium citrate allows the gold core to be coated with Pd. This layered bimetallic colloid is stabilized by trisulfonated triphenylphosphane and sodium sulfanilate. More than 90% metal can be isolated in the solid state and is redispersable in water in high concentrations. 

The bimetallic particles will be in a core-shell structure or alloy form, depending on the preparation route, miscibility and reductiOT kinetics of metal ions. As an example, bimetallic particles like Au/Ag are reported to exhibit Ag core and Ag/Au alloyed-shell type of stracture by the seed-growth method [2]. However, if the reductions are simultaneous in presence of a capping agent, Au/Ag nanoparticles form homogeneous alloy [3], When they are reduced simultaneously by the microemulsion method, Au/Ag nanoparticles can form homogeneous alloy [4] or an enriched in Au core-enriched in Ag shell structure [5], depending on the preparation conditions. 

Diameters of polymer spheres are tunable by changing reaction temperature, amount of reactants (monomers, initiator, and solvent), and stirring rates. Sphere diameter can also be increased by seed growth methods where once produced spheres are used as seeds. 

Ranjan R, Tsapatsis M. Microporous metal organic framework membrane on porous support using the seeded growth method. Chem Mater 2009 21 4920-4. 

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