Driven by the scientific challenges involved in the creation of nanostructures providing access to new materials with unusual properties, the study of hybrid materials based on Layered Double Hydroxides (LDHs) has developed considerably during the last decade. This feature article is intended to give a broad overview of organic–inorganic hybrid assemblies based on LDH materials including their synthesis and characterization, and pointing out their potential applications. The LDH interlayer gap supplies an interesting, constrained environment arising from the anisotropic accommodation of the guest molecule at the nanoscale. Particularly, this article underlines the importance of compatibility between the two components, i.e. the organic and inorganic parts, in terms of charge distribution and molecular size for the polymerization process of interleaved molecules. Exfoliation and staging phenomena are also described. Through several examples of the shape and function of interlayer organic anions, hybrid LDH materials are described for their potential properties in optic devices, as drug delivery systems, and also as nano- and macro-fillers in polymer nanocomposites and cements, respectively. Eventually, LDH hybrid materials merge into even more complex systems for which topical applications are listed.

Layered double hydroxides recovered after exfoliation have been characterized by solid state chemistry techniques. The nature of the recovered materials is highly dependant on the drying process; when gently dried, a well-ordered phase is obtained, either by freeze-drying or reconstruction, but the material becomes amorphous after evaporation of the solvent. Delamination was used to prepare interstratified LDHs, making this technique a new route to the formation of a wide range of tunable materials.

The dissolution of microcrystalline cellulose in 1-butyl-3-methylimidazolium acetate [C₄C₁Im][OAc] was studied using a solid–liquid equilibrium method based on polarized-light optical microscopy from 30 to 100 °C. We found that [C₄C₁Im][OAc] could dissolve as much as 25 wt% of cellulose at temperatures below 100 °C. The structure of the composite phase obtained after cooling a solution of 16 wt% of cellulose in [C₄C₁Im][OAc] was analyzed by low angle X-ray diffraction showing the absence of microcrystalline cellulose, but depicting an extensive long range isotropic ordering. With the aim of improving the dissolution of cellulose in the ionic liquid, dimethyl sulfoxide, DMSO, was added as a co-solvent. It was observed that it enhances the solvent power of the ionic liquid by decreasing the time needed for dissolution, even at low temperatures. In order to understand what makes DMSO a good co-solvent, two approaches were followed. Firstly, we studied experimentally the mass transport properties (viscosity and ionic conductivity) of [C₄C₁Im][OAc] + DMSO mixtures at different compositions and, secondly, we assessed the molecular structure and interactions around glucose, the structural unit of cellulose, by means of molecular dynamics simulations. As expected, DMSO dramatically decreases the viscosity and increases the conductivity of the mixtures, but without inducing cation–anion dissociation in the ionic liquid. These results were confirmed by molecular simulation as it was found that the presence of a 0.5 mole fraction concentration of DMSO does not significantly affect the hydrogen-bond network in the ionic liquid. Furthermore, molecular dynamics shows that in the [C₄C₁Im][OAc] + DMSO equimolar mixture, DMSO does not interact specifically with glucose. We conclude that DMSO improves the solvation capabilities of the ionic liquid because it facilitates mass transport by decreasing the solvent viscosity without significantly affecting the specific interactions between cations and anions or between the ionic liquid and the polymer. The behavior of DMSO as a co-solvent was compared with that of water and it was found that water molecules are more probably found near glucose than those of DMSO, thus interfering with ionic liquid–glucose interactions, which might explain the unsuitability of water as a co-solvent for cellulose in ionic liquids.