Self-Piling Silicate Rods and Dendrites from High Aspect-Ratio Clay Platelets

Abstract

We observed the formation of unique rod-like microstructures by self-assembling of random mica platelets with a high aspect-ratio and counterion charged. The platelets are polydisperse with dimensions of 300−1000 nm in width and 1 nm in thickness and are prepared from the exfoliation of layered synthetic-fluorinated-mica. These platelets of polygon shape are characterized by transmission electron microscopy and atomic force microscopy. When finely dispersed in water followed by controlled evaporation, the randomized silicate platelets self-align into a rod-like morphology. The restructuring force is attributed to the intensive attraction of surface charges on high aspect-ratio platelets. The resulting thin platelets tend to self-align in a size-selective manner through face-to-face piling into rod-like microstructures of 3−20 μm in length and 300−1000 nm in diameter (observed by field emission-scanning electron microscopy). The self-assembled rods, under an ultrasonic treatment, may further rearrange into fern-leaf dendrites via the process of fragmentation and restacking. The sequential transformation of platelet microstructures in a hierarchical manner allows a morphological manipulation for constructing patterns of regularity.