EXCLAIM

The last decade has seen the development of a novel class of industrially useful composite materials where the filler material consists of well-dispersed two-dimensional anisotropic clay platelets. The size of these platelets in at least one dimension is in the nanometer domain. The purposes of this project, which was graded by EPSRC as "Outstanding", were (i) to widen the current application of low clay fraction clay-polymer nanocomposites into a new areas through the development of a diverse range of high clay-fraction intercalated nanocomposites; (ii) to gain a fundamental understanding into the mechanisms of formation of high clay fraction intercalated clay-polymer nanocomposites and how the atomic scale structure correlated with the bulk materials properties; (iii) to explore methods and limits for processing and testing the clay-polymer nanocomposites produced for mechanical behaviour.

Layered double hydroxides (LDHs) are another class of layered materials with wide application as catalysts, sorbents, fillers in composites, and nano-scale reaction vessels. However, unlike the more commonly encountered cationic clays, the LDHs have postively charged sheets, with very high charge density and anions between the sheets in the interlayer region. We are especially interested in LDHs containing organic anions as these have attracted much attention for their solid-base properties for fine chemical synthesis. An experimental group at the University of Cambridge are our main collaborators in this work.

Smectite clays, such as montmorillonite, undergo structural alterations upon thermal treatment. We have used electronic structure simulations to investigate the dehydroxylation behaviour and the migration of Li⁺ cations in montmorillonite clays to attempt to elucidate the results of experimental studies by other researchers. Using such first principles molecular dynamics simulations allows us to derive simulated spectroscopic results such as Fourier transform infra-red spectra to compare with experiment whilst maintaining an exact knowledge of the chemical and physical processes operating within our model systems.