Xia and co-workers reported the production of controlled morphologies such as nanocubes and nanowires by controlling the molar ratio between silver nitrate and PVP.Īn emulsion is a liquid in liquid dispersion. Yang and co-workers used polyol method to produce icosahedral and cubic gold particles on the order of 100–300 nm by careful regulation of the growth rate for each crystallographic direction. The polyol synthesis process has also been used for the synthesis of bimetallic alloys and core-shell nanoparticles.
It has been reported that as-synthesized glycolate precursors can be converted to their more common metal oxide derivatives when calcined in air, while maintaining the original precursor morphology. Ethylene glycol is also used as a crosslinking reagent to link with metal ion to form metal glycolate leading to oligomerization. The solvent that is mostly used in polyol method in metal oxide nanoparticles synthesis is ethylene glycol because of its strong reducing capability, high dielectric constant, and high boiling point. There are several reports that have studied the synthesis of oxide sub-micrometer particles and these include Y 2O 3, V xO y,Mn 3O 4, ZnO, CoTiO 3, SnO 2, PbO, and TiO 2. The polyol process can be taken as a sol-gel method in the synthesis of oxide, if the synthesis is conducted at moderately increased temperature with accurate particle growth control. Polyol method can also be used in producing nanoparticles in large scale. This method allows flexibility on controlling of size, texture, and shape of nanoparticles. The nonaqueous solvents that are used in this method have an advantage of minimizing surface oxidation and agglomeration. This method uses nonaqueous liquid (polyol) as a solvent and reducing agent. The Polyol method is a chemical method for the synthesis of nanoparticles.