Design and preparation of bionanocomposites based on layered solids with functional and structural properties

Biopolymers such as chitosan, pectin, alginate, t-carrageenan and gelatin, can be assembled to layered solids by direct intercalation via ion exchange in the case of smectites or a 'co-organised assembly' method in the case of layered double hydroxides (LDHs). Layered perovskites can be delaminated and combined with the biopolymers following a delamination/restacking procedure. The starting cationic exchange ability of smectites such as montmorillonite is turned into an anionic exchange capacity due to the intercalated chitosan excess, while an opposite effect is observed in the case of the LDHs after incorporation of alginate, pectin or t-carrageenan. This fact, combined with the good mechanical properties of these bionanocomposites, allows their use as the sensing phase of potentiometric sensors applied to the recognition of cationic or anionic species in aqueous solution. Besides, perovskite-gelatin bionanocomposites can be processed as robust translucent films with highly oriented two-dimensional particles exhibiting elevated dielectric permittivity values.