The Blanket Effect: How Turning the World Upside Down Reveals the Nature of Graphene Oxide Cytocompatibility

Extensive cytocompatibility testing of 2D nanocarbon materials including graphene oxide (GO) has been performed, but results remain contradictory. Literature has yet to account for settling-although sedimentation is visible to the eye and physics suggests that even individual graphenic flakes will settle. To investigate settling, a series of functional graphenic materials (FGMs) with differing oxidation levels, functionalities, and physical dimensions are synthesized. Though zeta potential indicates colloidal stability, significant gravitational settling of the FGMs is theoretically and experimentally demonstrated. By creating a setup to culture cells in traditional and inverted orientations in the same well, a "blanket effect" is demonstrated in which FGMs settle out of solution and cover cells at the bottom of the well, ultimately reducing viability. Inverted cells protected from the blanket effect are unaffected. Therefore, these results demonstrate that settling is a crucial factor that must be considered for FGM cytocompatibility experiments.

Carbon-based polymer nanocomposites as dielectric energy storage materials

Nanostructured polymeric materials based on conductive nanofillers have promising applications in the energy storage field owing to the extraordinary characteristics of the nanofillers. Conductive nanofillers, such as graphene nanoplatelets, are characterized by small size, extraordinary surface area to volume ratio, high aspect-ratio and extremely low electrical resistivity. In this work, the dielectric behaviors and the corresponding energy storage capabilities of high aspect-ratio carbon nanofiller/polymer composites were reviewed. At the electrical percolation point, a conductive composite exhibits a sudden and remarkable enhancement in dielectric constant and dielectric loss. The challenge is to maintain the increase in dielectric constant while preventing the increase in dielectric loss. Various physical and chemical methodologies have been followed to overcome this challenge including surface chemistry modifications, physical alignment of nanofillers and utilizing of hybrid mixtures. Promising results were reported to minimize the energy loss due to the conductive network formation. Nanocomposites with a dielectric constant of 10³ and dielectric loss of only 0.08 were successfully fabricated. However, more work is still needed for a further enhancement in dielectric constant and reduction in the energy loss and to improve the storage capabilities of the nanocomposites.

Epoxy/graphene nanocomposites – processing and properties: a review

Graphene, a 2D fullerene, is a unique material because of its exceptional set of properties. This review has been focused on the processing methods and mechanical, electrical, thermal, and fire retardant properties of epoxy/graphene nanocomposites.