Polysaccharide Nanocomposites Reinforced with Graphene Oxide and Keratin-Grafted Graphene Oxide

Nanocomposites of polysaccharide matrices, chitosan starch, and carboxymethyl cellulose-starch reinforced with graphene oxide and graphene grafted with keratin were developed. Composites films had been prepared for the casting/solvent evaporation method. The interaction and distribution of graphene materials in the biopolymer matrices were analyzed by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM), and the thermomechanical properties were examined using dynamic mechanical analysis. The nanocomposites of the chitosan-starch matrix improved their mechanical properties substantially, with respect to the film without reinforcing, obtaining an increase of 929% in the storage modulus (E', 35 degrees C) with only 0.5 wt % of graphene oxide and outstanding increments in E' at 150 and 200 degrees C when keratin-grafted graphene oxide is incorporated (0.1 wt %). In contrast, the graphene oxide incorporated into the carboxymethyl cellulose-starch matrix tends to decrease the stiffness of the film, behaving in a manner opposite to that of nanocomposites of the chitosan-starch matrix. Similarly, the incorporation of graphene grafted with keratin shows a decrease in the rigidity of the resulting material. In this way, the importance of compatibility between the graphene and the host matrix to achieve a fine control of interface and manipulate the final properties of the material is demonstrated.