Surface modification of hydrophobic nanocrystals using short-chain carboxylic acids.

Acrylic, acetic and methacrylic acids which are short-chain carboxylic acids have been applied to modify the surface of oleic acid-coated TiO(2) nanorods (NRs) and oleic acid/oleylamine-coated Fe(3)O(4) nanoparticles (NPs). The short-chain carboxylic acids not only acted as modifying ligands but also as anti-solvents during the ligand exchange processes. The prepared products have been characterized using TEM, HRTEM and FTIR spectroscopy. The results show that the acrylic acid-exchanged TiO(2) and Fe(3)O(4) solution remain stable even after six months, showing no agglomeration. Such acrylic acid-exchanged nanocrystals (NCs) prepared in this work could also be well-dispersed in other polar solvents such as ethanol and ethanol/water mixtures. On the contrary acetic acid and methacrylic acid-exchanged TiO(2) solutions were not stable due to the presence of remaining oleic acid on the TiO(2) surface. This approach has been shown to be effective in making hydrophilic TiO(2) NRs and Fe(3)O(4) NPs and can also be applied to other NCs covered by different hydrophobic ligands.