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M. Raza, G. Kickelbick:
"Investigation Of The Effect Of pH, Precursor Concentration and Bonding Modes during Functionalization of Titania Nanopartiocles with Organic Surfactants";
Talk: Minisymposium: From Molecules to Materials, Saarbrücken, Deutschland; 2009-09-10 - 2009-09-11; in: "From Molecules to Materials", (2009).

In recent years TiO2 has bcen studied extensively as photocatalyst to deal with environmental pollution and water purification. The light-induced redox reaction at the surface of photocatalytic titania nanoparticles often results in the decomposition of organic compounds. We investigated the synthesis of photocatalytically active anatase titania nanoparticles and their surface-functionalization with molecules that interact with the surface by different anchor groups and the change of the surface groups under photocatalytical conditions
In a first step anatase nanoparticles were synthesized through the sol-gel method. The obtained monodispersed particles were functionalized with sodium dodecylsulphate (SDS), dodecyl carboxylic acid (DDA), dodecyl amine (DDAmine) and dodecylphosphonic acid (DPA). Different concentrations of each surfactant were used under varying pH values to optimize the conditions for surface coverage and it was noted that pH between 2 to 3 is best for functionalizing titania nanoparticles with the above mentioned four surfactants. The bonding modes and percentage of surface coverage of the obtained titania nanoparticles were investigated applying FT-IR, TGA and elemental analysis. The results show that SDS, DDA and DDAmine are bonded to the titania surface through electrostatic interaction whereas DPA is bonded through covalent interaction.
UV Stability of these surface modifications was investigated by exposing them to UV photocatalytical reactor with a power of 18W for one week and 150 W for three days. It was noted that surface functionalizations were stable under 18W and there were some chemical alterations observed at 150 W. These surface modifications were successfully repeated in Pickering emulsions as well to investigate anisotropic surface-functionalization of titania nanoparticles.

Project Head Guido Kickelbick:
Chemisch massgeschneiderte Grenzflächen in Nanokompositen