Long-time translational self-diffusion in isotropic dispersions of colloidal rods

A dispersion of fluorescent colloidal silica coated boehmite rods with length L'325 nm and diameter D '46 nm, dispersed in dimethylformamide, is synthesized. The concentration dependence of the long-time translational self-diffusion coefficient Ds L is measured with fluorescence recovery after photobleaching up to a rod volume fraction f50.22. A linear dependence of Ds L on concentration is found up to (L/D)f51. At higher concentration Ds L levels off and decreases to 3% of its value at infinite dilution for (L/D)f51.5. @S1063-651X~97!05110-6#