Water dispersible graphene noncovalently functionalized with tryptophan and its poly(vinyl alcohol) nanocomposite

Graphene sheets functionalized noncovalently with aromatic amino acid, tryptophan (Tryp), were prepared by reducing graphene oxide through hydrazine hydrate. Tryp-functionalized graphene is water dispersible and can be stabilized for several months. Atomic force microscopy (AFM), X-ray diffraction (XRD), UV–vis absorption and Raman spectroscopy were used to investigate the nanostructures and the properties of graphene. Application of the graphene dispersion to poly(vinyl alcohol) (PVA) with the help of tryptophan to prepare nanocomposite was also carried out. And the PVA/graphene nanocomposite was characterized by thermogravimetric analysis (TGA) and tensile testing. A 23% improvement in tensile strength and moderate increases in Young’s modulus and thermal stability for PVA were achieved by adding only 0.2 wt% graphene sheets.