Preparation of chitosan/graphene oxide composite film with enhanced mechanical strength in the wet state

Chitosan/graphene oxide composite films have been prepared by the mixing aqueous solution of chitosan and graphene oxide in the present of diluted acetic acid. The structure, thermal stability and mechanical properties of the composite films have been investigated by the wide-angle X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, thermogravimetry analysis, and mechanical test. The results obtained from those different studies revealed that chitosan and graphene oxide could mix with each other homogeneously and the mechanical properties of the as-prepared films were improved significantly over that of the pure chitosan film, especially at wet state. The tensile strength of the film of chitosan/graphene oxide (5:1, w/w) is 1.7 times higher than that of the pure chitosan film at dry state while it is 3 times higher at wet state. In addition, the composite films also showed a high storage modulus up to 200 °C. The composite films have potential application as biomaterials or packing materials.