Size stabilization of nanoparticles by polysaccharides: effectiveness in the wet and curing steps.

Starch suspension proves to be a useful matrix for the hydrolytic route to metal oxide nanoparticles, due to its size-stabilization effect, which works also at high temperatures. To understand the type of interaction between the organic part and the oxide particles, various parameters, such as viscosity, temperature, degree of polymerization, and organic/inorganic kinds of dispersant, are tested through x-ray diffraction (XRD), transmission electron microscopy (TEM), solid-state nuclear magnetic resonance (NMR), and thermogravimetric mass spectra (TG-MS) analyses of the obtained SnO₂ nanopowders. Results highlight the unique role of starch compared with other hydrophilic dispersants that do not ensure effective size stabilization on curing up to 600 °C. The proof comes from the study of pyrolysis of the residual organic groups surrounding the particles. They are chelating carboxylic species that prevent the coalescence among metal oxide nanoparticles. [ABSTRACT FROM AUTHOR]