Chitosan bionanocomposites prepared in the self-organized regime

Abstract

Bionanocomposites in the self-organized regime are prepared when chitosan is gradually charged in the course of progressive change of pH by hydrolyzing D-glucono-δ-lactone in solutions of nanoparticles bearing negative charges on their surface. This novel approach is applicable to the formation of monolithic hydrogels and films. Here bionanocomposites of chitosan with clay nanoparticles of saponite and sepiolite having various geometry and with oxidized multiwall carbon nanotubes are considered. Structural organization of hydrogels and films is studied by scanning and transmission electron microscopy as well as small angle X-ray scattering. Jellification is caused by generation of three-dimensional network from fibrils, whereas films have pronounced stratified layer (nacre-like) structure from stacked nanoparticles and aligned chitosan macromolecules. Special attention is paid to mechanical properties of films that are improved drastically with introducing nanoparticles.

Cellulose Mineralization as a Route for Novel Functional Materials

“…Clays are applied traditionally as fillers in the paper industry . Bio‐nanocomposites of biopolymers with them is a rapidly emerging class of biofriendly materials . However, there is a severely limited number of publications at present on their bio‐nanocomposites with cellulose.…”

Chitosan Hydrogels and Bionanocomposites Formed through the Mineralization and Regulated Charging

“…It did not exceed sometimes 15–25 nm . Similar, but shorter microparticles were observed on the film surface . They were sometimes arranged in the form of spherulite or “flowers”.…”

“…By adding an acid or alkali, one can manipulate the charging (Figure ) We used this property to regulate the electrostatic interactions of chitosan with oppositely charged polymers and nanoparticles that led us to an original approach of the hydrogel fabrication . The approach was extended then for the bionanocomposite and film preparation …”

“…Nanoparticles bearing charges may be considered as an analog of charged macromolecules . This leaves room for looking at their associates with chitosan via the electrostatic interactions in the context of theory of polyelectrolyte complexes . When chitosan is gradually charged in the presence of dispersed nanoparticles, a solution is jellified in a like manner of hydrogel formation with anionic polysaccharides.…”

“…The charging reveled itself in our unsuccessful attempts to prepare a monolithic hydrogel of chitosan with sepiolite. Its formation was observed only for saponite that exceeded the sepiolite in few times by the surface charge density of nanoparticles …”