An efficient approach to derive hydroxyl groups on the surface of barium titanate nanoparticles to improve its chemical modification ability

Highly hydroxylated barium titanate (BaTiO3) nanoparticles have been prepared via an easy and gentle approach which oxidizes BaTiO3 nanoparticles using an aqueous solution of hydrogen peroxide (H2O2). The hydroxylated BaTiO3 surface reacts with sodium oleate (SOA) to form oleophilic layers that greatly enhance the dispersion of BaTiO3 nanoparticles in organic solvents such as tetrahydrofuran, toluene, and n-octane. The results of Fourier transform infrared spectroscopy confirmed that the major functional groups on the surface of H2O2-treated BaTiO3 nanoparticles are hydroxyl groups which are chemically active, favoring chemical bonding with SOA. The results of transmission electron microscopy of SOA-modified BaTiO3 nanoparticles suggested that the oleate molecules were bonded to the surfaces of nanoparticles and formed a homogeneous layer having a thickness of about 2 nm. Furthermore, the improved dispersion capability of the modified BaTiO3 nanoparticles in organic solvents was verified through analytic results of its settling and rheological behaviors. (C) 2008 Elsevier Inc. All rights reserved.