Disaggregation and surface modification of nano-size diamond by ultrasound exposure: Relationships among acoustic intensity, disaggregation, and surface modification

We used ultrasound exposure to perform disaggregation and surface modification of aggregated nano-diamond particles. We formed a standing-wave sound field using a Langevin transducer to drive a stainless-steel vibrating disk installed at the bottom of a water tank, and generated efficient acoustic cavitation. With 20 minutes of ultrasonic exposure, we were able to reduce aggregated nano-diamond particles with average particle diameters of 5µm to average particle diameters of 100 nm or less. We also confirmed that we had improved the zeta potential, an index of surface modification, by a factor of more than two. Furthermore, we used a hydrophone to measure the sound field inside the water tank, and calculated the average acoustic intensity at 800W/m² or more to demonstrate that the nano-diamond surfaces had been modified. We confirmed that the zeta potential and average particle diameter of the nano-diamonds could be maintained for at least 150 days after ultrasound exposure. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(12): 10– 18, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20268