Chitosan and graphene oxide/reduced graphene oxide hybrid nanocomposites - Evaluation of physicochemical properties

In this paper we have presented results of our studies on chitosan/graphene oxide (CS/GO) and chitosan/reduced graphene oxide (CS/rGO) hybrid nanocomposites. First, L-ascorbic acid (L-AA), grape extract (GE), and green tea extract (GT) were tested as green reducing agents for reduced graphene oxide synthesis. Structural and chemical properties of the obtained rGOs were examined by X-ray diffraction (XRD), attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). Next, GO and rGOs were introduced into the chitosan matrix to prepare a series of hybrid nanocomposites. Their physicochemical properties were evaluated by XRD, ATR-FTIR, DSC (differential scanning calorimetry), SEM (scanning electron microscopy), wettability and mechanical testing. It was found that all of the introduced nanofillers affected the structural, thermal, microstructural, mechanical, and surface properties of the nanocomposites. Addition of GO resulted in the increase of Young's modulus by 35%, while the composites reinforced with rGO_L-AA were soft and easy to bend in hand without cracking. We showed that simultaneous synthesis of rGO-L-AA and fabrication of the CS/rGO_L-AA hybrid nanocomposite allowed to fully exploit the potential of the chitosan/rGO system. The developed materials, after detailed biological characterization, may be potentially applicable in bone and cartilage tissue engineering.