Polymer–clay nanocomposites: an overview with emphasis on interaction mechanisms

There has been a surge of interest in polymer–clay nanocomposites over the past decade. This review surveys these new materials with emphasis on the debate surrounding interaction mechanisms and the behaviour of intercalated polymer in clay galleries. Swelling properties, high cation exchange capacities, high aspect ratio and large surface area give smectite clays the new role of high performance filler for thermoplastic or thermosetting polymers for the creation of intercalated or exfoliated nanocomposites. These nanocomposites can be prepared by three routes: in situ polymerisation, solution methods, or melt processing. Modification of either clay or polymer can change the type of polymer–clay composite. X-ray diffraction and transmission electron microscopy are often employed as the main characterisation techniques to establish the state of the clay. A very low volume fraction of clay significantly improves the mechanical and barrier properties of the pristine polymer, which makes these nanocomposites very promising materials.