Ordered assemblies of clay nano-platelets.

We demonstrate five methods of arranging smectite clay tactoids into layered arrangements as a part of the quest for the biomimetic simulation of nacre. Provided the clay is not fully exfoliated, the tactoids retain sufficient rigidity for alignment and we present micrographs which demonstrate these ordered structures. This paves the way for exploration of the high mineral filler end of polymer-clay nanocomposites which can approach the high aragonite volume fraction of nacre. The clay was dispersed in water without additives by ultrasonic agitation, cleaned by partial sedimentation and the resulting suspension was subjected to controlled phase separation by sedimentation, centrifugation, controlled rate slip casting, filtration and electrophoresis. Well-aligned parallel layers of platelets were obtained from all the five methods, the best stacking being associated with slip cast layers. Polyethylene oxide was incorporated into these well-aligned tactoids.