Layered structure graphene oxide/methylcellulose composites with enhanced mechanical and gas barrier properties

Layered structure graphene oxide (GO)/methylcellulose (MC) composite films with excellent mechanical and gas barrier properties were achieved for the first time by a simple solvent evaporation assisted assembly of GO/MC composite solutions. 1, 3 and 5 wt% of GO composites with respect to MC were fabricated and denoted as GO1, GO3 and GO5, respectively. The interactions of the hydrophobic associated domains of MC (formed during solvent evaporation) with the cloud of GO (hydrophobic interaction) and the oxygen-containing groups of MC with the oxygen-containing functional groups of GO (H-bonding interaction) govern the formation of self-assembled thick MC coated layered structure GO/MC composites. The obtained composite films were highly flexible and characterized by field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), wide angle X-ray scattering (WAXS), Simultaneous Thermal Analysis (STA), and mechanical and oxygen gas permeation studies. The FESEM analysis shows the formation of a layered structure as well as good dispersion of thick MC coated GO sheets in the MC matrix. WAXS studies also illustrate that the GO sheets remain in a highly exfoliated state in the MC matrix. The FTIR results indicate the presence of interfacial interaction between the GO and MC molecules. The GO/MC composite films exhibit a significant enhancement of mechanical properties compared to pure MC films. The stress at break and Young's modulus of GO5 were determined to be 104 +/- 3 MPa and 3.8 +/- 0.2, respectively. In addition to the mechanical properties, the oxygen gas barrier properties of the composites were also enhanced significantly. The GO1 film shows a 98% decrease of oxygen permeation with respect to pure MC films.