Development of Hybrid Materials Based on Chitosan, Poly(Ethylene Glycol) and Laponite® RD: Effect of Clay Concentration

In the context of increasing interest in biomaterials with applicability in cosmetics and medicine, this research aims to obtain and characterize some hybrid materials based on chitosan (CS) (antibacterial, biocompatible, and biodegradable), poly(ethylene glycol) (PEG) (non-toxic and prevents the adsorption of protein and cell) and Laponite® RD (Lap) (bioactive). The rheological properties of the starting dispersions were investigated and discussed related to the interactions developed between components. All samples exhibited gel-like properties, and the storage modulus of CS/PEG dispersion increased from 6.6 Pa to 657.7 Pa by adding 2.5% Lap. Structural and morphological characterization of the films, prepared by solution casting method, was performed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and polarized light microscopy (POM). These analyses proved the incorporation of Lap into CS/PEG films and revealed the morphological changes of the films by the addition of clay. Thereby, at the highest Lap concentration (43.8%), the “house of cards” structure formed by Lap platelets, which incorporate chitosan chains, as evidenced by SEM and POM. Two stages of degradation between 200 °C and 410 °C were evidenced for the films with Lap concentration higher than 38.5%, explained by the existence of a clay-rich phase (given by the clay network) and chitosan-rich one (due to the intercalation of chitosan in the clay network). CS/PEG film with 43.8% Lap showed the highest swelling degree of 240.7%. The analysis of the obtained results led to the conclusion that the addition of clay to the CS/PEG films increases their stability in water and gives them greater thermal stability.