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 π 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.