Sedimentation and diffusion in suspensions of sterically stabilized colloidal platelets

Ultracentrifuge and light scattering measurements are performed to study static and dynamic properties for a suspension of well-defined platelike colloids to first order in concentration. Both the form factor and the diffusion coefficient at infinite dilution match theoretical expressions if polydispersity is incorporated. This yields values for the polydispersity corresponding with values obtained from electron microscopy. Application of the generalized Stokes-Einstein relation to the measured concentration dependence of sedimentation and collective diffusion coefficients yields a second virial coefficient B(2) for the platelets which is slightly smaller than the theoretical value for hard disks.