Monodisperse spherical titania particles of variable sizes are produced in a sol-gel synthesis from Ti(EtO) 4 in ethanol with addition of a salt or a polymer solution. The influence of different salt ions or polymer molecules on the size and the size distribution of the final particles was investigated. The amorphous hydrous titania particles were characterized by electron microscopy, thermogravimetry, 1 H-MAS NMR, X-ray absorption spectroscopy, and electrophoresis. Nitrogen absorption measurements revealed that the addition of polymers yields hollow and porous titania colloids.

Monodisperse spherical ZrO 2 particles were prepared by controlled hydrolysis of zirconium tetraalkoxide in alcoholic solution. Ageing the reaction solution at 60°C for 4 h yields particles with sizes in the range between 200 and 2000 nm. The influence of various ions and surfactants on the final product was investigated. Stable suspensions of coated, monodisperse, zirconia particles were prepared by hydrolysis and subsequent polymerisation of tetraethoxysilane in an alkaline ethanol solution. Thermal analysis revealed that the weight loss of bound water occurred below 400°C and is about 35 %. The phase transition from amorphous zirconia to

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Monodisperse spherical hollow and non hollow titania particles of variable sizes are produced in a sol gel synthesis from Ti(EtO)4 in ethanol. Hollow spherical particles of rutile were obtained by coating colloidal polystyrene beads with a titanium oxide hydrate layer and subsequently calcination at elevated temperatures in ol\ygen atmosphere. The non hollow titania particles were produced in the presence of salt or polymer solution. The influence of different salt ions or polymer molecules on the size and on the size distribution of the non hollow particles was investigated. Nitrogen absorption measurements revealed that the addition of polymers yields porous titania colloids.

Monodisperse magnetic polymer colloids have been synthesized via a three‐step procedure and evidence for the formation of homogeneously distributed magnetite particles in the polymer matrix is presented (see Figure). Owing to their magnetic behavior and uniform particle size, these colloids are perfect candidates for the fabrication of photonic bandgap materials.