Surface modification of hydrophobic nanocrystals using short-chain carboxylic acids

Abstract

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 3O 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 3O 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 3O 4 NPs and can also be applied to other NCs covered by different hydrophobic ligands.