Green Solvent Processed Cellulose/Graphene Oxide Nanocomposite Films with Superior Mechanical, Thermal, and Ultraviolet Shielding Properties

This study reports for the first time a green process to fabricate Lyocell fiber and graphene oxide (GO) based novel cellulose/graphene oxide nanocomposite (CGN) flexible films for ultraviolet (UV) shielding applications. A polyethelene glycol (PEG) mediated solvent system was utilized to make CGN films via solution casting route. To improve the dispersion of GO sheets in a cellulosic matrix, a reactive interface was formed in between cellulose and oxygenic functionalized groups of GO sheets via cross-linking them with epichlorohydrin (ECH). The addition of GO sheets in cellulose matrix leads to the synergistic changes, which were observed in the structure and surface morphology of CGN nanocomposite films. Enhanced dispersion of GO sheets in CGN films was observed in morphological investigations which is attributed to the adequate cellulose-GO interaction by hydrogen bonding and led to significant enhancement in the mechanical and thermal properties. The tensile strength and Young's modulus of CGN films with 2 wt % GO loading (CGN2) increased to 89 MPa and 4.3 GPa from 55.6 MPa and 2.1 GPa, respectively, as compared to the neat cellulosic film. Additionally, the CGN films exhibited remarkable UV shielding capability which increased with GO loading in a cellulose matrix. The CGN2 film (2 wt % GO loading) possessed outstanding absorbance in the wavelength range of 280 to 400 nm and showed almost complete shielding (similar to 99%) of UV rays in both the UV-B and the UV-A regions. Moreover, the ultraviolet protection factor of the CGN2 film demonstrated more than 80-fold increase compared to that of the neat cellulose film. The obtained CGN nanocomposite film has a high potential for applications in the field of UV protection.