Direction-specific van der Waals attraction between rutile TiO2 nanocrystals

We report measurement of this attraction between rutile nanocrystals, as a function of their mutual orientation and surface hydration extent. At tens of nanometers of separation, the attraction is weak and shows no dependence on azimuthal alignment or surface hydration. At separations of approximately one hydration layer, the attraction is strongly dependent on azimuthal alignment and systematically decreases as intervening water density increases. Measured forces closely agree with predictions from Lifshitz theory and show that dispersion forces can generate a torque between particles interacting in solution and between grains in materials.

Source: ScienceNOW - April 27, 2017 Category: Science Authors: Zhang, X., He, Y., Sushko, M. L., Liu, J., Luo, L., De Yoreo, J. J., Mao, S. X., Wang, C., Rosso, K. M. Tags: Materials Science reports Source Type: news