ausblenden:
Schlagwörter:
anatase - nanoparticle assembly - nanostructures - nonaqueous synthesis - surface chemistry
Zusammenfassung:
Powders of nanoparticles composed of surface-functionalized anatase crystals with diameters of about 3 nm self-organize into different structures upon redispersion in water. The assembly is directed by a small amount of a low molecular weight functional ligand (the “assembler”) adsorbed on the surface of the nanoparticles. The ligand functionality determines the anisotropy of the resulting structures. Multidentate ligands like trizma (HOCH2)3CNH2 and serinol (HOCH2)2CNH2 with a chargeable terminal group preferentially induce the formation of anisotropic nanostructures of several hundreds of nanometers in total length, whereas all the other investigated ligands (ethanolamine H2N(CH2)2OH, glycine hydroxamate H2NCH2CONHOH, dopamine (OH)2C6H3(CH2)NH3Cl, tris (HOCH2)3CCH3) mainly lead to uncontrolled agglomeration. Experimental data suggest that the anisotropic assembly is a consequence of the water-promoted desorption of the organic ligands from the {001} faces of the crystalline building blocks, inducing their preferred attachment along the [001] direction. The use of polydentate and charged ligands to functionalize the surface of nanoparticles provides thus a versatile tool to control their arrangement on the nanoscale.
