A method for imaging single clay platelets by scanning electron microscopy

Abstract

Summary:A method for preparing and observing clay platelets for size and shape analysis using scanning electron microscopy (SEM) was developed. Samples of the clay platelets were prepared by polyelectrolyte-assisted adsorption onto a pyrolytic graphite surface. The use of graphite as a substrate was advantageous because of the low number of secondary electrons emitted from it during imaging by SEM. The resulting low background noise allowed the emission from the ~1 nm thick clay sheets to be clearly visualized. Images of centrifuged montmorillonite showed large exfoliated platelets with lateral dimensions between 200 and 600 nm. In contrast, uncentrifuged montmorillonite appeared to contain a large amount of unexfoliated clusters. Although it was not possible to obtain high-quality images of the smaller sheets of Laponite RD, the images of this material did contain size features comparable to the ~30 nm 2 size reported previously using light scattering, as well as transmission electron and atomic force microscopies.

Fluorohectorite/LDPE nanocomposites: The role of organomodifiers and compatibilizer

“…In the field of nanocomposites, the exfoliation of layered materials generates enormous surface areas that enable an effective reinforcement for polymers . Unlike graphite or other layered materials, water‐swellable clays can be easily exfoliated into nanosheets of ∼1 nm in an aqueous environment . This interesting property allows the possibility of obtaining nano‐sized clays for use in nanocomposites.…”

Nanoparticle dispersion in polymer nanocomposites by spin-diffusion-averaged paramagnetic enhanced NMR relaxometry: scaling relations and applications

“…[1][2][3][4][5][6][7][8][9][10][11] Among the most common inorganic fillers are clay particles, best described as stacks of platelets in which platelets are 1 nm thick with lateral dimensions of hundreds of nanometers. 12,13 Platelets can be delaminated from stacks by exfoliation so that clay particles may be characterized by the number of platelets per stack. The degree to which platelet stacks are exfoliated and dispersed in matrices is governed by interfacial interactions and processing.…”

Dr Barbara S. Neumann: clay scientist and industrial pioneer; creator of Laponite®

“…2); they were among the first scientists to apply this technique to a synthetic clay mineral. Laponite® remains a notoriously difficult specimen to analyse by microscopic methods (Rouse et al , 2004). The average diameter of the first disc-shaped Laponite® particles produced by Dr Neumann and her team was ~60–80 nm (Fig.…”