The curious case of the misbehaving colloidal sheet

Colloidal sheets were created such that 2D layers of polystyrene spheres were levitated in deionized water far above the bottom of the sample cell and then allowed to sediment. The curious observation is that as time elapses the sheet retains its 2D shape; in some circumstances it becomes convex, in other circumstances it buckles, but in all circumstances the 2D character persists during the sedimentation process. This talk describes the phenomenon and presents tentative explanation.