Synthesis of click-coupled graphene sheet with chitosan: Effective exfoliation and enhanced properties of their nanocomposites

Graphene sheet (GS) is functionalized with chitosan via a click coupling between azide-functionalized chitosan and alkynyl-decorated graphene oxide. The coupling is confirmed by Fourier transform infrared and X-ray photoelectron spectroscopy, and the complete exfoliation of GS in the chitosan matrix is confirmed by X-ray diffraction measurements. With the addition of a small amount of the click coupled GS-f-CS (2 wt%) in the chitosan matrix, the breaking stress and tensile modulus of a chitosan composite film is increased by more than 200%. In addition, the click coupled GS-f-CS shows higher antimicrobial activity than pure chitosan. The click coupling approach used for graphene sheet may be very effective for enhancing both the functional and mechanical properties of composites by employing a suitable target polymer.