Exceptional Viscoelastic Properties in Graphene Oxide Films.

Materials that combine high stiffness with effective damping are in high demand across various industries. While polymers excel in damping, they often lack stiffness and thermal stability. Conversely, metals and ceramics boast high mechanical and thermal properties but lack damping. This study demonstrates that graphene oxide (GO) and reduced graphene oxide (rGO) films can achieve exceptional viscoelastic properties across a wide temperature range. Furthermore, it explains the damping mechanisms and structural characteristics that influence the unique viscoelastic behavior of GO and rGO films. Through comprehensive characterizations, this study correlates the structure and spatial variation in local strain (measured with in situ Raman microscopy) of GO and rGO films with their storage and loss moduli. This correlation links these properties to the water loss as a function of the temperature rise. GO and rGO films exhibited a damping coefficient of 0.2-0.4 while maintaining stiffness values of 10-20 GPa in the 30-120 °C range. These high damping values were attributed to intermittent slippage and hydrogen bond density between the constituent sheets. Numerical modeling was conducted to further elucidate the mechanisms responsible for the properties noted in these films. This study enhances our understanding of the viscoelastic properties of GO films and offers a new potential material for applications across various fields.