Shear-induced dynamic polarization and mesoscopic structure in suspensions of polar nanorods.

Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin, Germany.
Physical Review Letters (Impact Factor: 7.73). 02/2009; 102(2):028301. DOI: 10.1103/PhysRevLett.102.028301
Source: PubMed

ABSTRACT We investigate the spatiotemporal behavior of sheared suspensions of rodlike particles with permanent dipole moments. Our calculations are based on a self-consistent hydrodynamic model including feedback effects between orientational motion and velocity profile. The competition between shear-induced tumbling motion and the boundary conditions imposed by plates leads to oscillatory alignment structures. These give rise to a spontaneous time-dependent polarization generating, in turn, magnetic fields. This novel shear-induced effect is robust against varying the boundary conditions. The field strengths are of a measurable magnitude for a broad parameter range.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Combining computer simulations and experiments we investigate the role of particle charges on the layering behavior of confined silica colloids (slit-pore geometry). To this end we perform colloidal-probe atomic-force-microscope measurements of the oscillatory solvation force of confined suspensions involving three different particle sizes (and resulting total charges). For all systems, the wavelength of the oscillations as function of volume fraction is found to display a power-law behavior characterized by similar exponents. However, the results for different particle sizes cannot be simply mapped onto each other, which demonstrates the importance of correlation effects due to the different Coulomb coupling. Our experimental findings are consistent with the results from parallel Monte Carlo computer simulations of a (DLVO) model system.
    Soft Matter 03/2010; 6:2330-2336. · 4.15 Impact Factor


Available from
May 20, 2014