Polyelectrolyte nanocomposite hydrogels filled with cationic and anionic clays

Polyelectrolyte nanocomposite hydrogels (NHGs) were synthesized. NHGs were formed from a polymer matrix composed of a cationic, anionic, and alkylated chitosan polymer modified with vinyl groups (ChAV) to achieve greater crosslinking. Cationic and anionic clays montmorillonite and hydrotalcite, respectively, were used as nanofillers to introduce electrostatic interaction with the matrix. NHGs were obtained via in situ polymerization. The ChAV and NHGs were then characterized. Based on X-ray diffraction and transmission electron microscopy results, the morphology of the nanocomposite was generally intercalated with some nanocomposites showing exfoliation. Rheological studies revealed improvements in shear modulus of NHGs with respect to hydrogel without clay. Lower relaxation times were noted as the clay content increased and it was attributed to the interactions between the clay sheets and the polymer. In conclusion the rheological properties of the material are improved with the addition of clay and the interactions present with the polymer matrix.