Gaining Insight into the Structure and Dynamics of Clay–Polymer Nanocomposite Systems Through Computer Simulation

Abstract

Clay minerals belong to a wider class of solids known as layered materials, which may be defined as ‘crystalline materials wherein the atoms in the layers are cross-linked by chemical bonds, while the atoms of adjacent layers interact by physical forces’ [1]. Both clay sheets and interlayer space have one dimension in the nanometre range. Cationic clays are the predominant naturally occurring minerals with aluminosilicate sheets carrying a negative charge. Therefore, the interlayer guest species are positively charged to compensate the layer charge [2]. In anionic clays, also known as layered double hydroxides (LDHs), the interlayer guest species carry a negative charge and the inorganic mixed metal hydroxide sheets are positively charged. In recent times, there has been a growing interest in anionic clays, although initial attention was focussed almost exclusively on the cationic clay materials. Reviews have appeared that often emphasise interesting properties and the use of experimental techniques to determine or at least infer the local structure of the clay sheet or intercalated material [3–5]. However, clays are polycrystalline materials and precise experimental location of interlayer species is extremely difficult.